Guidelines for Survelaince of Drug Resistance in TB

7/27/2019 Guidelines for Survelaince of Drug Resistance in TB

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Guidelines forsurveillance of drugresistance in tuberculosis

Fourth Edition


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Guidelines orsurveillance o drug

resistance in tuberculosisFourth Edition


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World Health Organization 2009

All rights reserved. Publications o the World Health Organization can be obtained rom WHO Press,World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791 3264;ax: +41 22 791 4857; e-mail: [email protected]). Requests or permission to reproduce or translateWHO publications whether or sale or or noncommercial distribution should be addressed toWHO Press, at the above address (ax: +41 22 791 4806; e-mail: [email protected]).

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All reasonable precautions have been taken by the World Health Organization to veriy the inor-mation contained in this publication. However, the published material is being distributed withoutwarranty o any kind, either expressed or implied. The responsibility or the interpretation and useo the material lies with the reader. In no event shall the World Health Organization be liable ordamages arising rom its use.

Cover: Photographs (top let and right) courtesy o Paolo Miotto, San Raaele Scientic Institute,Milan, Italy; (bottom) WHO. Points and lines depict survey and routine surveil lance data providedto the Global Project on Anti-Tuberculosis Drug Resistance Surveillance.

Designed by minimum graphicsPrinted in France

WHO Library Cataloguing-in-Publication Data:

Guidelines or surveillance o drug resistance in tuberculosis 4th ed.

WHO/HTM/TB/2009.422

1.Antitubercular agents pharmacology. 2.Tuberculosis, Multidrug-resistant epidemiology. 3.Drug resistance. 4.Epidemiologic surveillance methods.5.Guidelines. I.World Health Organization.

ISBN 978 92 4 159867 5 (NLM classication: WF 360)


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Contents

Acknowledgments vii

Introduction ix

Part I. Principles o anti-tuberculosis drug resistance surveillancein the Global Project 1

1. Mechanisms o surveillance that produce data representative o a

geographically-dened population 3

1.1 Surveillance systems based on routine drug susceptibility testing 4

1.2 Periodic surveys 5

1.3 Sentinel surveillance systems 6

1.4 Regimen surveys 7

2. Standardized stratication o results by patient categories 8

2.1 Patient treatment history classications 8

2.2 Age groups, sex, HIV status, and other patient biographicaland clinical actors 10

3. Quality-assured laboratory methods or determining resistance to

rst- and second-line drugs 13

3.1 WHO-recommended methods o drug susceptibility testing 133.2 Consensus on critical concentrations or rst- and second-line

drug susceptibility testing 15

3.3 Selection o drugs to be tested or susceptibility 17

3.4 Quality assurance o drug susceptibility testing 18

3.4.1 Internal quality control 18

3.4.2 External quality assessment and the role o theSupranational Reerence Laboratory Network (SRLN) 19

4. Ethical considerations 21

Contents


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Guidelines or surveillance o drug resistance in tuberculosis

iv

Part II. Conducting a survey 23

5. Survey planning 25

5.1 Setting specic objectives 25

5.2 Development o a protocol and time schedule 265.3 Minimum required acilities or a survey area 26

5.4 Sampling o cases 27

5.4.1 Dening the sampling rame 28

5.4.2 Sample size 29

5.4.3 Sampling strategies 30

5.5 Formation o a national coordination team 32

5.6 Budgeting 335.7 Training 33

5.8 Laboratory preparedness 34

5.9 Pilot study 35

6. Survey logistics 36

6.1 Inclusion and exclusion criteria 36

6.2 Patient intake 36

6.2.1 Clinical inormation orm 376.3 Sputum collection, processing and transport 38

6.4 Central reerence laboratory processes 39

6.4.1 Decontamination 39

6.4.2 Cultures 39

6.4.3 Identication 40

6.4.4 Internal quality assurance at the survey laboratory 41

6.4.5 Susceptibility testing, including rechecking 41

7. Survey data management and analysis 43

7.1 Data management 43

7.2 Data analysis 44

7.2.1 Imputation o missing values 46

7.2.2 Sampling design eects on standard errors 47

7.2.3 Other considerations or data analysis 48

7.3 Interpretation o results 49

Reerences 51


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Annees 55

Annex 1a First-line anti-tuberculosis drug resistance results 57

Annex 1b Second-line anti-tuberculosis drug resistance results 59

Annex 1c Multidrug resistance stratied by age groups and sex 60Annex 1d Multidrug resistance stratied by patient HIV status 61

Annex 2 Supranational reerence laboratory list 62

Annex 3a Example o a prociency testing results orm (rst-line drugs) 65

Annex 3b Example o a prociency testing results orm (second-line drugs) 66

Annex 4a Example o a prociency testing analysis sheet (rst-line drugs) 67

Annex 4b Example o a prociency testing analysis sheet

(second-line drugs) 68Annex 5a Example o a rechecking analysis sheet (rst-line drugs) 69

Annex 5b Example o a rechecking analysis sheet (second-line drugs) 70

Annex 6 Drug resistance survey protocol checklist 71

Annex 7 Weighted cluster sampling 74

Annex 8 Survey budget template 76

Annex 9 Example o a clinical inormation orm 77

Annex 10 Sae shipment o inectious material 79

Annex 11 Sample size or rechecking TB strains 80

Contents


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Acknowledgments

ts pae e e geles was we by:

Wayne van Gemert, Matteo Zignol, Dennis Falzon, Philippe Glaziou, Karin Weyer

develpme s cme was ge by e llwg pael exeal expes:

Lucia Barrera, Instituto Nacional de Enermedades Inecciosas, ANLIS Dr. CarlosMalbran, Buenos Aires, Argentina

Chiang Chen-Yuan, International Union Against Tuberculosis and Lung Disease,

Paris, FranceFrank Cobelens, Center or Poverty-related Communicable Diseases, Academic

Medical Center, Amsterdam, The Netherlands

Ted Cohen, Harvard Medical School, Boston, USAArmand Van Deun, Prince Leopold Institute o Tropical Medicine, Antwerp,

BelgiumSian Floyd, London School o Hygiene and Tropical Medicine, London, UK

PG Gopi, ormerly o the Tuberculosis Research Center, Chennai, IndiaSusan van den Ho, KNCV Tuberculosis Foundation, The Hague, The Nether-

landsTimothy Holtz, Centers or Disease Control and Prevention, Atlanta, USA

Grace Kahenya, Management Sciences or Health, Lusaka, ZambiaMichael Kimerling, Bill & Melinda Gates Foundation, Seattle, USACsaba Kdmn, European Centre or Disease Prevention and Control, Stock-

holm, SwedenDavide Manissero, European Centre or Disease Prevention and Control, Stock-

holm, SwedenSabine Rsch-Gerdes, Forschungszentrum Borstel, National Reerence Center

or Mycobacteria, Borstel, GermanyCharalambos Sismanidis, London School o Hygiene and Tropical Medicine,

London, UKNorio Yamada, Research Institute o Tuberculosis, Japan Anti-Tuberculosis

Association, Tokyo, Japan

Acknowledgments


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Cbg Wl heal ogaza (Who) sa:

Samiha Baghdadi, Andrei Dadu, Laura Gillini, Reuben Granich, YuHong Liu,

Wilred Nkhoma, Nicoletta Previsani, Andreas Reis; and Haileyesus Getahun,Ernesto Jaramillo, Knut Lnnroth, Paul Nunn, Mukund Uplekar, under the

direction o Mario Raviglione

The authors also express their gratitude to Michael Selgelid (Centre or AppliedPhilosophy and Public Ethics, Australian National University) and AliceCorinaldi (Stop TB Italia) or their assistance in developing the chapter on ethical

considerations.Portions o this updated edition o the guidelines are based on materials

developed by Abigail Wright (WHO).

WHO wishes to acknowledge the generous nancial contributions o theUnited States Agency or International Development (USAID) and the LillyMDR-TB Partnership or the production o this document.

The secretariat o the Global Project on Anti-Tuberculosis Drug ResistanceSurveillance wishes to thank the national authorities and the institutions hosting

each o the national and supranational reerence laboratories or their continuedvital support or the project.


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Introduction

Introduction

This ourth edition o World Health Organization (WHO) Guidelines or surveil-lance o drug resistance in tuberculosis is an updated version o earlier editions pub-

lished in 1994 (1), 1997 (2) and 2003 (3). These guidelines incorporate the 2007WHOInterim recommendations or the surveillance o drug resistance in tuberculosis(4), as well as the conclusions o an Expert Committee Meeting on Anti-Tuber-culosis Drug Resistance Surveys held in Geneva in September 2008. In addition,

the guidelines take into account recent advancements in laboratory diagnosticsand subsequent WHO guidance, including the 2008 WHO Policy guidance ondrug-susceptibility testing (DST) o second-line anti-tuberculosis drugs (5) and the2008 WHO Policy Statement, Molecular line probe assays or rapid screening o

patients at risk o multidrug-resistant tuberculosis (6).Furthermore, these updated guidelines incorporate the wealth o experience

gained rom 15 years o the Global Project on Anti-Tuberculosis Drug Resist-

ance Surveillance (716) (hereinater, reerred to as the Global Project), a projectinitiated by WHO and the International Union Against Tuberculosis and LungDisease (The Union).

Since its launch in 1994, the Global Project has collected and analysed data

on drug resistance rom surveys o sampled patients and rom national surveil-lance systems rom an ever increasing number o settings around the world. The

4th Global ReportAnti-tuberculosis drug resistance in the world (15), published in2008, included data provided rom over 100 geographical settings.

The Global Project has served as a common platorm or country, regionaland global level evaluation o the magnitude and trends in anti-tuberculosisdrug resistance. It has also quantied the growing global burden o multidrug-

resistant tuberculosis (MDR-TB)1 and, in recent years has started to documentthe spread o extensively drug-resistant tuberculosis (XDR-TB).2 Since the inclu-sion o MDR-TB management in the new and comprehensive Stop TB Strategy(17, 18), a new and undamental role o the Global Project has been to assist

1 MDR-TB:Mycobacterium tuberculosis with resistance to isoniazid and riampicin.2 XDR-TB:Mycobacterium tuberculosis with resistance to isoniazid and riampicin (MDR-TB), plus

additional resistance to a fuoroquinolone and a second-line injectable agent.


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countries in planning the scale-up o MDR-TB management with essential dataon national burden and prevalence o drug resistance patterns.

The aim o the current guidelines is to assist national tuberculosis controlprogrammes (NTPs) in developing the strongest possible mechanisms o sur-

veillance, starting rom periodic country-specic surveys o sampled patients,but moving towards surveillance systems based on routine drug susceptibilitytesting (DST). Mechanisms or carrying out surveillance vary rom country to

country, but these guidelines promote certain standardized criteria or surveil-lance within the Global Project to ensure that results are comparable betweenparticipating countries, as well as within countries over time.

The target audience o these guidelines is the NTP, and in particular a coordi-

nation team or surveillance composed o the NTP manager, laboratory special-ist, logistics specialist, epidemiologist, and statistician.

This edition o the guidelines is divided into two parts. Part I describes theprinciples o the Global Project that should be considered undamental to both

surveillance systems and periodic surveys. Part II describes the steps neededto plan and implement a survey, as well as manage and interpret the collecteddata.

Drug resistance surveillance in the Global Plan to STOP TB (20062015) and in the2007 and 2009 World Health Assembly resolutions

Worldwide capacity to conduct drug resistance surveillance has increased sincethe initiation o the Global Project, but large gaps still exist. As part o the GlobalPlan to STOP TB (20062015) (19), the Stop TB Partnerships Working Group on

MDR-TB has established a set o ve specic objectives or MDR-TB control by2015, two o which provide targets or drug-resistance surveillance. Firstly, by2015, representative and reliable data should be available on the global magni-tude o MDR-TB, trends in high MDR-TB prevalence countries, and the relation-

ship between MDR-TB and HIV/AIDS. Secondly, by 2015, all countries shouldcarry out drug DST or all previously treated TB patients. In the Eastern Euro-

pean Region, where MDR prevalence is highest, DST should also be done or allnew TB patients, while in the Latin American, South-East Asian and Western

Pacic Regions, DST should be done or a subset o new TB patients, ocused onpeople at increased risk o MDR-TB.

At the 2007 World Health Assembly, resolution WHA60.19 Tuberculosis con-trol: progress and long-term planning recognized the importance o the situationand the trends o multidrug-resistant and extensively drug-resistant tuberculo-sis as barriers to the achievement o the Global Plans objectives by 2015, and the

need or an increased number o Member States participating in the network othe Global Project on Anti-Tuberculosis Drug Resistance Surveillance and orthe required additional resources to accomplish its task (20).

The need or strengthening surveillance or drug-resistant TB was reiterated


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by the 2009 World Health Assembly resolution WHA62.15 Prevention and control

o multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis, thaturges all Member States to achieve universal access to diagnosis and treatmento multidrug-resistant and extensively drug-resistant tuberculosis, including by

means o strengthening health inormation and surveillance systems to ensuredetection and monitoring o the epidemiological prole o multidrug-resistantand extensively drug-resistant tuberculosis and monitor achievement in its pre-

vention and control (21).

Changes rom previous editions o the Guidelines

Readers amiliar with the 2003 edition o the Guidelineswill notice the ollowingupdates and clarications in surveillance methodology are incorporated into the

current edition:1. Establishment o surveillance based on routine DST o previously treated

TB cases1 is a priority in all settings, with country-specic prioritization opatient subcategories based on history o previous treatment.

2. In settings that do not yet have sucient capacity or surveillance based onroutine DST o all new TB cases, surveys should be conducted periodicallyamong new cases, e.g. every three to ve years. In settings currently lacking

capacity or surveillance based on routine DST o all previously treated TBcases, separate sampling o previously treated cases should be considered inthe design o periodic surveys.

3. New rapid phenotypic and genotypic laboratory drug susceptibility testing

methods endorsed by WHO may be used or surveillance purposes. Integra-tion o line probe assays into the TB diagnostic algorithm can allow or rapidscreening o patients or resistance to riampicin and, as a proxy, or MDR-TB.Resistance to isoniazid can also be detected using line probe assays, though

resistance may be underestimated due to lower sensitivity o this tool.4. At a minimum, surveillance should evaluate susceptibility to the ollowing

drugs:a) isoniazid and riampicin;b) I resistance is detected to riampicin, then susceptibility to the fuoro-

quinolones and second-line injectable agents most oten used in the set-ting should also be tested. Testing or susceptibility to the rst-line drug

ethambutol should also be considered.5. Surveys should be conducted at a minimum on smear positive pulmonary

cases; inclusion o smear negative cases requires consideration o the impli-cations or logistics and laboratory capacity, given that smear negative cases

are less likely to be culture positive.

1 For denitions o new and previously treated cases, see section 2.1Patient treatment history clas-sications.


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6. Establishment o sentinel surveillance networks or estimating the burdeno resistance requires the establishment o systems ree o signicant bias.Periodic surveys should be considered the preerred alternative until capacityis reached or establishment o a surveillance system based on routine DST

that produces data representative o a geographically-dened population. Asentinel system could be used as an interim approach or countries expand-ing routine DST to all retreatment cases.

7. Drug resistance surveillance activities, generally conducted only in the publicsector under the NTP, can be enhanced via initiatives that gradually involvehealth care providers and laboratories outside o the NTP.

8. Inclusion o HIV testing in anti-tuberculosis drug resistance surveillance can

produce valuable inormation or both the national TB control programmeand individual patients. Thereore, in close collaboration with national AIDS

programmes and other HIV stakeholders, all possible eorts must be madein order to make such inormation available as part o anti-tuberculosis drug

resistance surveillance activities. Standard and rapid methods o HIV testing(e.g. oral tests) should be used in line with existing global and national HIVtesting guidelines.

9. Statistical and epidemiological methodology is a undamental aspect odesigning surveys that sample patients, and appropriate technical assist-ance should be received in the early stages o planning. In particular, orsurveys that use cluster-based sampling methods, results should be adjusted

to correct or biases introduced by these sampling techniques. Missing valuesshould also be accounted or, e.g. using multiple imputation techniques whenpossible.

10. MDR-TB management is a component o the Stop TB Strategy and WHO

Member States have committed themselves to achieve universal access todiagnosis and treatment by 2015. Thereore, all drug resistance surveillanceactivities should be linked to patient treatment and care. Planning a compre-

hensive treatment programme or patients identied during a survey as hav-

ing drug-resistant TB should run in parallel to planning the survey itsel.11. Survey protocols should be reviewed and approved by ethical committees or

institutional review boards.


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Part I.Pcples a-beclssg essace svellace

e Glbal Pjec


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1.

Mecanisms o sureillance tat producedata representatie o a geograpically-defned population

Surveillance means the systematic ongoing collection,collation and analysis o data or public health purposes and

the timely dissemination o public health inormation orassessment and public health response as necessaryrom the International Health Regulations (2005),adopted by the 58th World Health Assembly

The Global Project was initiated in 1994 with the aim o collecting and evaluat-ing data on anti-tuberculosis drug resistance in a systematic and ongoing wayaround the world ollowing three main principles:

1. Reported data should be representative o the TB patients in the country/geographical setting under study. In surveys using sampling, the sample size

should be determined to permit standard epidemiological analysis;

2. The patients history should be careully obtained and available medical recordsreviewed to clearly determine whether the patient has previously received anti-

tuberculosis drugs. This is essential to distinguish between drug resistanceamong new cases and drug resistance among previously treated cases;

3. The laboratory methods or anti-tuberculosis drug susceptibility testing

should be selected rom among those that are WHO-recommended, and alllaboratory processes should be quality-assured in cooperation with a partnerSupranational Reerence Laboratory (SRL).

Within the standardized methodological ramework designed or the Project,two main mechanisms o surveillance are able to collect data on drug resistance

representative o a geographically-dened population to allow or comparisonacross settings and within settings over time: surveillance based on routine DSTo all TB patients and periodic surveys o sampled TB patients.

The mechanism o surveillance that is more strongly able to ull systematic

and ongoingrequisites is a system that continuously collects DST data. As parto the Global Plan to Stop TB 20062015, it is an aim that all countries will becarrying out DST or all previously treated TB patients by 2015. In the WHO-

1. Mechanisms o surveillance that produce data representative o a geographically-defned population


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dened European Region the aim is to achieve DST among all new TB patients.In the rest o the world, the aim is to achieve DST or new TB patients who are athigher risk o poor treatment outcomes.

In the meantime, as capacity or surveillance based on routine DST grows,

it is clear that alternative measures are needed in many parts o the world inorder to evaluate the magnitude o drug resistance in the most systematic andongoing manner as possible, given region-specic and country-specic circum-

stances and capacity. Thereore, in many countries, periodic surveys o sampledTB patients currently orm the basis o surveillance.

Each country should take a long-term view o surveillance and should designa system that best ts its needs. This system should be based on capacity that is

sustainable, and ideally that allows the evaluation o trends over time an inher-ent objective o surveillance. Countries may combine components rom the two

mechanisms o surveillance in order to meet their specic needs and capacities.It should be noted that the Global Project measures resistance only in new-

ly registered episodes o TB (among new and/or previously treated cases), theresults o which can be used in the estimation o incidence o MDR-TB. The Glo-bal Project does not measure the proportion o prevalent TB cases with resistance.

This means the results cannot be used to directly calculate the number o existingdrug-resistant cases, or consequently the need or second-line anti-tuberculosisdrugs. Nevertheless, knowing how many new episodes o MDR-TB arise eachyear can be a valuable tool in planning a response to MDR-TB. Readers interested

in a more in-depth discussion o the limitations o the current drug resistancesurveillance methodology are reerred to other sources (22,23).

1.1 Surveillance systems based on routine drug susceptibility testing

A surveillance system based on routine DST o all TB cases is able to provide con-tinuous inormation on drug resistance patterns among patient groups, and is

thereore able to accurately detect trends, as well as localized outbreaks. Approx-

Epanding coverage o surveillance by including health care providersoutside o the NTP

We esgg a mecasm svellace a gegapcally-ee ppla tB cases, e slcse e les all eleva eal cae pves mally lke e aal tB cl p-gamme (ntP) (pblc, vlay, pvae a cpae) e agss a eame tB, clgg-essa tB. Labaes se e ntP eakg mycbaceal cle a dSt eally sl becle svellace acves. icls cae pves cg se e ntP svellacewll eqe pacla ae assg qaly saas agscs, samplg, a aa ecg

a epg. Svellace sl ally be cce e pblc sec a pvae-sec labaes cllaba w e ntP qaly assace. Pblc-pvae mx aves ca seve as plams gaally vlve e pvae-sec labaes g essace svellace acves.


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imately hal o the countries currently reporting data to the Global Project havesurveillance systems with quality-assured laboratories that can provide suchroutine DST data on all TB cases (or that miss only a negligible number o suchcases). Due to the resources required to maintain such a system, these surveil-

lance systems are typically ound in higher income countries. In these countries,DST results usually orm the basis o the clinical management o drug-resistantTB using tailored or individualized treatment regimens.

Ideally, in the near uture every country should have in place universal DSTor both clinical care and surveillance purposes. However, in settings wherecapacity is currently not available or routine DST o all TB patients, a surveil-lance system should be organized with priority on establishment o routine

DST o cases at high risk or drug-resistant TB. At a minimum, a system o routine DSTshould be established among all previously treated TB cases, with country-specic prioritization

o patient subcategories. Subcategories include cases ater treatment ailure, returncases ater deault, relapses, and other previously treated cases (For more details

on subcategories, see section 2.1Patient treatment history classications).Signicantly, in a number o countries that provide routine DST to patients,

surveillance continues to be substandard due to low quality o laboratory proc-

esses, weaknesses in data recording and reporting, a lack o standardization inpatient classications, and signicantly less than perect coverage. Data romthese surveillance systems are not included in the Global Project. However, sig-nicant eorts are currently being made in many settings to improve quality,

which will allow or a growing number o countries to supply continuous sur-veillance data to the Global Project.

1.2 Periodic surveys

In resource-constrained settings where capacity is currently not available orroutine DST o all TB cases, surveys can be conducted to measure drug resist-

ance among a sample o patients representative o the geographically-denedpopulation under study. When properly constructed and periodically conducted,

such surveys provide a sound estimation o the resistance prole o all TB casesin the population under study and can detect general trends over time. Approxi-

mately hal o the countries currently reporting data to the Global Project pro-vide data rom surveys.

Periodic surveys can provide much o the same critical inormation provid-

ed by a surveillance system, but they are less eective in detecting localizedoutbreaks, may produce results with margins o error that prevent meaningulanalysis or determination o trends, and are suspect to biases inherent in sam-

pling. However, when considering secondary benets, conducting surveys canstrengthen laboratory capacity, transport and reerral systems, as well as evalu-ate the correct classication o patients by treatment history. Surveys can alsoprovide a platorm or operational and other types o research, including study-



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ing risk actors or drug resistance (see section 2.2.3 Other patient biographical

and clinical actors).Nationwide surveys are desirable or programmatic reasons, but surveys at

smaller administrative levels should also be considered in large countries or

when national capacity is insucient. The size and scope o the survey shouldbe determined by the ability o the NTP to ensure quality, and urthermoredepends on the specic objectives o the survey. Starting at smaller administra-

tive levels such as cities or districts, and then expanding to nationwide surveysis one way o developing capacity while ensuring quality. However, results romsurveys at the subnational level should not be extrapolated to estimate the bur-den at the national level.

In settings without capacity or surveillance based on routine DST o new TB cases, surveys

o new TB cases should be conducted periodically, e.g. every three to ve years . Surveys can

be conducted more requently in settings i there is reason to believe that rateso drug resistance are changing. This could be due to introduction o new

treatment regimens, programmatic changes in the NTP, any signicant socio-economic disturbance, or past observed trends in drug resistance. However, inorder to detect a signicant dierence in proportions between two surveys con-

ducted with a short time interval in between, a very large sample size wouldbe required. A single survey can provide critical inormation to the national TBcontrol programme on the burden o resistance and common patient drug resist-ance proles at a certain point in time. However, it should be noted that without

plans or repetition at regular intervals, such an activity cannot by denition beconsidered surveillance.

As described earlier, surveillance based on routine DST o all previouslytreated cases should be established as a priority in all countries.

1.3 Sentinel surveillance systems

Some countries with well-established laboratory networks have opted or asentinel system or surveillance. This type o system continuously reports DST

results o all TB cases rom a selection o laboratory or hospital sites, and there-ore can be useul in documenting trends and detecting outbreaks or localized

epidemics o drug resistance.For countries where resources, the health care system structure, or geograph-

ical eatures preclude routine DST o all patients or surveys o sampled patients,

the establishment o a sentinel surveillance system may be an option. A sentinelsystem could be a useul interim approach or countries intending to expandroutine DST to all retreatment cases while moving towards this goal. The imple-

mentation o a sentinel network requires good planning in order to produce datathat are useul or planning and monitoring, even i not strictly representative.Key issues to consider include whether the characteristics o the TB cases romthe reporting units risk being biased (e.g. i there is an excess o urban settings


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or places where individuals at risk or drug-resistance congregate) when com-pared with the population o interest, and whether the units are likely to detectand report a majority o cases occurring in their areas.

1.4 Regimen surveysRegimen surveys measure rst-line and/or second-line drug resistance among

a group o selected patients that cannot be considered representative o a patientpopulation. These surveys can help determine the predominant patterns o drugresistance, and can be useul in providing guidance on appropriate regimensor MDR-TB treatment or particular patient groups. These include return cases

ater treatment ailure, chronic cases and symptomatic contacts o MDR-TB cas-es. Regimen surveys should be conducted in the process o developing MDR-TB

treatment programmes, or within selected centres or diagnostic units that regu-larly address high-risk cases.Regimen surveys do not need to be nationwide in scope. Organization o

these surveys can help build capacity or later surveillance based on routine DSTo high-risk cases. Due to their design, regimen surveys cannot provide data

that is representative o a geographically-dened population, nor can they pro-vide accurate data on trends.



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8Guidelines or surveillance o drug resistance in tuberculosis

2.

Standardized stratifcation o resultsby patient categories

2.1 Patient treatment history classications

The Global Project measures resistance in newly registered episodes o TB(including among new and previously treated patients) stratied by the patientsTB treatment histories. Forms in Annex 1A and 1B collect aggregated data on

resistance to rst-line and second-line drugs respectively, by treatment historycategory. Careul classication o treatment history is critical to allow or properand accurate interpretation o data. The ourth edition o WHO Guidelines ortreatment o tuberculosis (24) denes patient registration groups by history o pre-

vious treatment.

Defnition: New caseFor the purpose o surveillance, a new case is dened as a newly registered

episode o TB in a patient who, in response to direct questioning denies havinghad any prior anti-tuberculosis treatment (or up to one month), and in coun-tries where adequate documentation is available, or whom there is no evidence

o such history.Determining the proportion o drug resistance among new cases is vital in

the assessment o recent transmission.

Defnition: Previously treated caseFor the purpose o surveillance, a previously treated case is dened as a new-ly registered episode o TB in a patient who, in response to direct questioningadmits having been treated or TB or one month or more, or, in countries where

adequate documentation is available, there is evidence o such history. Chemo-prophylaxis should not be considered treatment or TB.

Previously treated cases (also reerred to as retreatment cases) are a hetero-geneous group composed o several subcategories:

Subcategories o previously treated cases

Denition: Relapse a patient whose most recent treatment outcome was cured

or treatment completed, and who is subsequently diagnosed with bacterio-logically positive TB by sputum smear or culture.


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Denition: Treatment ater ailure a patient who is started on a retreatment regi-

men ater having ailed previous treatment or TB. Failure is dened as sputum

smear positive at ve months or later during treatment. The treatment courseailed (an initial treatment course with rst-line drugs, a retreatment coursewith rst-line drugs, or a treatment course using second-line drugs) should be

specied.

Denition: Treatment ater deault a patient who returns to treatment, bacterio-

logically positive by sputum smear microscopy or culture, ollowing interruptiono treatment or two or more consecutive months.

Denition: Other retreatment all cases that do not t the above denitions. This

includes patients who were previously treated:

but the outcome o their previous treatment is unknown, and/or; who have returned to treatment with smear negative pulmonary TB or

bacteriologically negative extrapulmonary disease.

Note: Patients who are bacteriologically-positive at the end o (or returning rom)a second or subsequent course o treatment are no longer dened as chronic.Instead, they are classied by the outcome o their most recent re-treatmentcourse: relapsed, deaulted or ailed (according to the ourth edition o WHOGuidelines or treatment o tuberculosis (24)).

Evaluation o resistance among subcategories o previously treated cases iscritical or data interpretation, and provides crucial inormation or programmemanagement. Previously treated patients are at higher risk o having strains

Primary resistance: Paes w tB essa e me a-beclss gs, b w ave evebee pevsly eae tB, ae sa ave pmay essace ( al essace) e asms-s a g-essa sa. Pmay g essace s a eecal ccep, as sy p a-be-clss eame s e fcl accaely ascea (25). ressace amg ew cases (ee as casesw < e m sy eame) as bee selece as a pxy esmae pmay essace.

Acquired resistance: Paes agse w tB w sa a-beclss eame a sbseqelyacqe essace e me e gs se g e eame, ae sa ave evelpe acqeessace. i e pas, essace amg pevsly eae cases (ee as cases w e m sy eame) was se as a px y acqe essace; weve, s pae caeg y s w kw alsbe cmpse paes w ave bee e-ece w a essa sa, a paes w wee pmalyece w a essa sa a sbseqely ale eapy elapse.

teee, essace amg pevsly eae cases s a sel pxy ly acqe essace (26,

27). tly acqe essace ca be asceae ly e g sscepbly pae s eeme beee sa eame ay ewly egsee epse, as well as a a lae p eame a e e eame. Feme, av msclassyg e-ec w a essa sa as a case acqeessace, mlecla gepg sas wl be eqe (25).

2. Standardized stratifcation o results by patient categories


24/98


10

o TB resistant to one or more drugs, and are usually the group rom whichpatients are screened or inclusion in drug-resistant TB treatment programmes.The inormation gained rom surveillance can be used or regimen developmentand evaluation. Thereore, developing inormation about the size and composi-

tion o this population and the patterns o resistance in subcategories o previ-ously treated cases is extremely important or programmatic reasons. This canbe achieved by establishing a surveillance system based on routine culture and

DST o all such cases.

2.2 Age groups, se, HIV status, and other patient biographical and clinicalactors

2.2.1 Age groups and sex

Data on drug resistance stratied by age groups and sex can provide insight intorisk groups and eectiveness o specic TB control activities. Furthermore, themagnitude o drug resistance among younger age groups is more likely to beindicative o recent transmission than among older age groups, which are morelikely to be harbouring older inections.

The orm in Annex 1C collects inormation or the Global Project on MDR-TBby age groups and sex.

2.2.2 HIV status

Incorporation o HIV testing in anti-tuberculosis drug resistance surveillancemay yield important inormation to the national TB control programme on therelationship between HIV and drug resistant TB at the population level. It can

also provide critically important individual benets to HIV-inected patients,including better access to testing, early detection and rapid placement on treat-ment. Provider-initiated HIV testing is recommended or all TB patients, andpatients presenting with signs and systems o TB (28). Thereore, whenever pos-

sible, regardless o the state o the HIV epidemic in a particular setting, HIVtesting should be encouraged and HIV status inormation should be included

or all patients enrolled in anti-tuberculosis drug resistance surveillance. How-ever, HIV testing should be considered an integral part o anti-tuberculosis drug

resistance surveys in HIV-prevalent settings, which are dened as settings withan HIV prevalence o1% in pregnant women or 5% in TB patients.

The specic objectives or including HIV testing should be addressed when

developing a surveillance system or should be indicated in a survey protocol.Existing national policies on HIV testing and HIV surveillance should be ol-lowed, including the availability o counselling services, ensuring consent and

condentiality procedures. The national AIDS programme should be involvedin the planning and execution o the surveillance rom the beginning. RapidHIV tests (e.g. oral tests), in accordance with national HIV testing and surveil-


25/98

11

lance policies, are preerred methods o HIV testing compared with plasma orserum-based tests (e.g. ELISA) (29).

In settings with a low burden o either MDR-TB or HIV, incorporating HIV

testing into surveillance may not allow or statistically signicant determinationo the relative risk o resistance in HIV-positive compared with HIV-negative TBpatients. Furthermore, surveillance incorporating HIV testing should take into

account the limitations in interpretation o data due to incomplete inormationas a result o testing coverage, and proportion o patients opting out. Surveil-lance should be designed to dierentiate between negative test results and testsnot perormed.

The orm in Annex 1D collects inormation or the Global Project on MDR-TBby patient HIV status.

2.2.3 Other patient biographical and clinical actors

Inclusion o other patient biographical and clinical inormation to collect and

measure is optional, and selection should be based on the objectives o sur-veillance and planned data analysis. Optional variables to measure associations

between drug resistance and stratied patient groups include:

2. Standardized stratifcation o results by patient categories

The association between anti-tuberculosis drug resistance and HIV

obeaks g-essa tB amg hiV-psve paes ave bee wely cmee scmal ae cgegae segs, b lle ma s avalable ab e assca hiV a g-essa

tB a ppla level (30, 31). te 4 rep e Global project on anti-tuberculosis drug resistance sur-veillance epe a sgca assca bewee hiV-psve sas a Mdr-tB w segs (15).

tee ae w ma eass wy g-essa tB may be asscae w hiV. te s s e cmeeacqs slae ampc essace amg hiV-psve peple e eame tB, alg smay als be e sps eapy. A-beclss g malabsp as als bee cmee pae cs segs g hiV pevalece, wc sggess a hiV-psve tB paes may be ageae sk acqg g essace. te sec eas elaes expse. hiV-psve paes ag-essa tB paes may ave smla sk acs, sc as sy spalza, wc may meaa hiV-psve tB paes ae a a ge sk expse essa ms sease.

te epemlgcal mpac hiV e epemc g-essa tB s kw a may epe seveal acs. hiV-psve tB cases ae me lkely be smea egave. i a, elaye agss g essace a avalably eame (paclaly pevs yeas) ave le g ea aes peple lvg w hiV. B ese acs (smea egavy a s a sease e mal-y) may sgges a lwe ae geeal asmss. hweve, hiV-psve cases pgess me aply sease, a segs wee Mdr-tB s pevale (ee e geeal ppla e lcal pplasc as a spal a sc), s may lea ap evelpme a pl g-essa tB paes a beak.


26/98


12

sub-geographic location country o origin history o incarceration drug use

alcohol abuse tobacco use other country-specic actors.

Using surveys to study risk actors or drug-resistant tuberculosis

Sveys ca seve as a valable plam syg e cy- seg-specc cases g ess-ace a eyg e ms mp a ages eve (32). Sveys ca be esge cle

a sees qess vesgag peal sk acs, be aske paes evewe m mecalecs a e me elme. Feme, a sy seekg vesgae sk acs acqs amplca g essace ca es g sscepbly, ly bee eame, b als ae ale a eame cse.

rsk acs a may be evalae cle pae hiV sas a se aeval eame; M. tuber-culosis geype; ype a qaly pevs (a/ ce) eame a eame spevs; pev-s (a/ ce) ec cl pacces; cmps pevs (a/ ce) eame egmesclg se ampc e ca pase; pevs (a/ ce) sce gs se; sage xe-se cmbas. rsk acs evala ca als cle pssble scal eemas* clg

scecmc sas, eca level, emplyme, ec. a me ec sk acs sc as mal,cwg, abees, alcl abse, g se, smkg, ec. i sl be e a mlple sk acs acqs, amplca a asmss g essace may peae smlaesly a seg.

Evala ese peal sk acs sl be a csee a eseac acvy, a sl cmp-

mse e qaly e svey a aame s pmay bjecves.

* F examples w esg qess mease scal eema s, see L e al. (33), Aex 13 Assessing tuberculosis prevalence throug h population-based surveys. Who Wese Pacc reg, 2007 (avalablele a p://www.wp.w./eal_pcs/beclss/). ne: e examples pve may eqe ajs-me base lcal cs a e ppla e sy.


27/98

133. Quality-assured laboratory methods or determining resistance to frst- and second-line drugs

3.

Quality-assured laboratory metodsor determining resistance to frst-and second-line drugs

In settings around the world, laboratory capacity has repeatedly turned outto be the weakest link in developing a reliable system o surveillance o anti-

tuberculosis drug resistance. Establishment o quality-assured bacteriologyusing WHO-recommended methods is necessary or surveillance, and intro-duction o rapid methods or DST into the diagnostic algorithm should be con-sidered a priority in all settings.

3.1 WHO-recommended methods o drug susceptibility testing

Recent technological advances in laboratory diagnostics have expanded the listo WHO-recommended methods available or DST, and can signicantly reduce

the delay between detection o TB and diagnosis o rst-line and second-linedrug resistance. Rapid methods o DST allow or the timely design o appropri-

ate treatment regimens based on patients drug resistance proles using diag-nostics that can be easibly implemented in settings worldwide. This increasedcapacity or DST also translates into increased capacity or surveillance.

Ater comprehensive review, WHO has endorsed certain new DST method-

ologies, including molecular line probe assays and liquid culture systems. Dueto the dynamic nature o research and development, new technologies otherthan those described below may have been endorsed by WHO since the time o

writing o this publication.

3.1.1 Sl cle mes

Although newer liquid culture and certain genotypic methods or DST havebeen endorsed by WHO and are being established in national TB control pro-grammes worldwide, conventional phenotypic methods using solid media are

still more commonly used.Three solid culture methods using egg-based or agar-based media contin-

ue to be used around the world: the proportion method, the resistance ratiomethod, and the absolute concentration method. These methods are inexpen-

sive and highly standardized or testing susceptibility to many drugs, but theyhave the serious disadvantage o requiring up to eight weeks to produce a


28/98


14

denitive conrmation o pulmonary TB, and another six weeks to produceDST results.

O the three methods, the proportion method is the most commonly usedworldwide. DST critical concentrations or second-line drugs have not yet been

adequately validated or the resistance ratio and absolute concentration methods(5).

Methodology o each o the three methods is well-described elsewhere (3,3437), as are instructions or the preparation o the most commonly used egg-based media, Lwenstein-Jensen and Ogawa (38).

3.1.2 Lq cle mes

Compared with solid culture methods, liquid culture methods signicantly

reduce the turnaround time or results, while also moderately increasing sen-sitivity. With liquid culture, conrmation o pulmonary TB can be obtained inless than two weeks, and DST results in an additional one to two weeks. Useo liquid culture methods is possible or susceptibility testing or both rst-lineand second-line drugs. WHO has endorsed the use o liquid culture and DST

in low- and medium-income settings, provided that the required inrastructureand biosaety measures are in place, and that aordability and sustainability areensured (39). Procedures should be perormed strictly according to the manu-acturers instructions. The disadvantages o the liquid culture method include

a relatively high cost or equipment and consumables, the need or rapid specia-tion (since the recovery rate o non-tuberculosis mycobacteria may be high), andthe need or strict quality control measures to prevent contamination. Reading

o commercial liquid culture systems is now partially or ully automated, pre-venting human error and contamination to some degree.

Radiometric liquid culture systems are highly sensitive, ast, and used eec-tively in many settings, but are being phased out. This is due to their high cost

and problems related to the disposal o a large volume o radioactive material.

3.1.3 Mlecla le pbe assays

Molecular line probe assays are a genotypic method o DST that are used todetect the most common mutations oM. tuberculosis DNA that coner resist-ance to anti-tuberculosis drugs. Validated line probe assays have been endorsed

by WHO or use in screening patients or isoniazid and riampicin resistance,provided that technical expertise on molecular techniques and proper acilitiesare in place and sustainability is ensured (6). Such assays can be used or sur-veillance purposes.

Line probe assays have the great advantage o being able to produce resultswithin 24 to 48 hours, thus representing a revolutionary step orward in the abilityto rapidly conrm or rule out MDR-TB. Furthermore, they can be used direct-

ly on smear-positive sputum specimens, thereore providing lower biohazard


29/98

15

risks. Line probe assays are relatively simple to perorm and require only basicexpertise in polymerase chain reaction (PCR) techniques. Data rom system-atic reviews and meta-analyses to evaluate assay perormance results againstconventional DST methods have shown that line probe assays are highly sensi-

tive and specic or the detection o riampicin resistance, alone or in combina-tion with isoniazid, on isolates oM. tuberculosis and on smear positive sputumspecimens (6, 40). However, given the lower sensitivity o line probe assays in

detection o isoniazid resistance, resistance to isoniazid may be underestimatedusing this method.

The integration o line probe assays into MDR-TB screening algorithms cansignicantly reduce the demand on conventional culture and DST laboratory

capacity. Use o line probe assays also decreases costs o shipping rom diagnos-tic centres to laboratory acilities, i used only on smear positive specimens.

However, line probe assays are not a complete replacement or liquid or solidculture and DST. Culture is still required or smear negative specimens. In addi-

tion, conventional methods o DST are still necessary to detect resistance tosecond-line drugs, as well as ethambutol and streptomycin, as assays that detectgenetic mutations conerring resistance to these drugs are still under develop-

ment. Another barrier to widespread use o line probe assays is the cost o theequipment and consumables, as well as the potential need or laboratory reno-vations in order to establish the separate rooms required to prevent contamina-tion. Procedures should be perormed strictly according to the manuacturers

instructions.

3.2 Consensus on critical concentrations or rst- and second-line drugsusceptibility testing

There has long been a consensus on the methodologies, critical drug concentra-tions, and reliability and reproducibility o testing using conventional methods

or DST o rst-line anti-tuberculosis drugs. However, consensus on DST osecond-line drugs has only recently been tentatively established, with the pub-

lication o WHOsPolicy guidance on drug-susceptibility testing (DST) o second-lineantituberculosis drugs (5). The policy guidance is based on a robust assessment

o published studies combined with laboratory experience and expert opinion.It systematically evaluated available DST methods or all second-line drugs andestablished consensuses on the reliability and reproducibility o DST or rst-

line and second-line anti-tuberculosis drugs (see Table 1). However, additionalresearch is needed to assess the role o second-line DST results in guiding treat-ment regimen design.

Drugs are grouped in DST categories based on the ollowing broad criteriathat were used to assess the strength o available evidence. This was based ontwo or more criteria having been met or assigning a drug to a specic DST cat-egory between I and V:



30/98


16

Table1

.Curr

entstatusoDSTmethodolog

yandcriticalconcentrations

orrst-lineandsecond-l

ineD

ST

D

ruggroupa

Drug

DST

category

DSTmethod

available

DSTc

rtiticalconcentration(g/ml)

Lwenstein

-

Jensen

b

Middlebrook

7H10b

Middlebrook

7H11b

BACTEC460

MGIT960

Group1

Fs-leala

-tBages

isaz

rampc

Eambul

Pyazame

i iiiii

Sl,

lqu

Sl,

lqu

Sl,

lqu

Lqu

0.240.02.0

0.21.05.0

0.21.07.5

0.12.02.5

100.0

0.11.05.0

100.0

Group2

ijecablea-tBages

Sepmyc

Kaamyc

Amkac

Capemyc

Vmyc

iiiiiiiiV

Sl,

lqu

Sl,

lqu

Lqu

Sl,

lqu

ne

4.030.040.0

2.05.0

10.0

2.06.0

10.0

2.04.01.01.2

5

1.0 1

.02.5

Group3

Fluqules

Cpfxac

ofxac

Levfxac

Mxfxac

Gafxace

iii

iii

iViViV

Sl,

lqu

Sl,

lqu

Sl,

lqu

Lqu

Sl

2.02.0

2.02.02.0 1

.0

2.02.0

2.02.0 0

.5

1.02.02.00.2

5

Group4c

oalbaces

acsec-le

a-tBages

Eame

Pam

e

Cyclsee

teze

P-amsalcylcac

taceaze

iViViViViVV

Sl,

lqu

Sl,

lqu

Sl

ne

Sl,

lqu

ne

40.0

40.0

40.01

.0

5.0 2

.0

10.0 8

.0

2.51.2

5 2

.0

5.02.5

Group5c

Aubeculs

sageswuclea

ecacy(e

cmmeebyWho

ueuse

Mdr-tBpaes)

Clazme

Amxcll/clavulaae

Clamyc

Lezl

V V V V

Lqu

ne

ne

Lqu

4.0 1

.0

1.0

a

WhoGuideline

sfortheprogrammaticmanagementofdrug-

resistanttuberculosis(25).

b

iecppmeecmmee.

oeslme

ames(essacea,

absluecc

ea)avebeeaequaelyvalaesec-l

eugs.

c ruedSt

gup4a5ugssecmmee.

Cpfxacslgeecmmeeeaug-susc

epbleug-essatB(25).

Gafxac

lybeuseexcepalccumsaces(25).


31/98

17

I. Extensive published studies, extensive multicentre laboratory review, broadintermethod agreement, high stability o drug powder in vitro, consistentDST reliability and reproducibility, extensive clinical outcome data.

II. Extensive published studies, extensive multicentre laboratory review, lim-ited intermethod agreement, variable DST reproducibility (and thereorereliability), variable stability o drug powder in vitro, less extensive clinical

outcome data.

III. Less extensive published studies, limited multicentre laboratory review,

limited intermethod agreement, limited data on DST reproducibility andreliability, limited data on drug powder stability in vitro, limited clinicaloutcome data.

IV. Limited or no published studies, limited multicentre laboratory review,limited data or questionable DST reproducibility (and thereore reliability),instability o drug powder in vitro, no clinical outcome data.

V. No published studies, no multicentre laboratory review, reproducibility andreliability impossible to assess, unknown stability o drug powder in vitro,

no clinical outcome data.

3.3 Selection o drugs to be tested or susceptibility

Due to the diculties in treating patients with MDR-TB, determining theproportion o TB cases with isoniazid and riampicin resistance is extreme-ly important. Furthermore, resistance to both o these drugs can be reliably

measured by standardized techniques, resulting in high sensitivities and spe-cicities.

Thereore, susceptibility testing or both isoniazid and riampicin should orm

the backbone o all drug-resistance surveillance. Among the other rst-lineanti-tuberculosis drugs, testing or streptomycin and ethambutol may alsobe included in surveillance, as these drugs are widely used throughout the

world and are tested or in rounds o prociency testing among the Suprana-tional Reerence Laboratory Network (SRLN). However, SRLN reliability osusceptibility tests or streptomycin and ethambutol are lower than reliabilitycorresponding to isoniazid and riampicin (41). It is dicult to standardizesusceptibility or pyrazinamide on solid media and the cost o liquid DST is

high. Thereore, this drug should not be routinely included in the selection odrugs to be tested or surveillance purposes.

Furthermore, due to the extreme obstacles in treatment options or XDR-TB,

evaluation o the proportion o MDR-TB cases that have XDR-TB strains shouldalso become a component o drug resistance surveillance.



32/98


18

Thereore, in TB cases with detected riampicin resistance (a strong surrogatemarker or MDR-TB, especially in areas with high prevalence o MDR-TB1),susceptibility to the fuoroquinolones and second-line injectable agents2 mostoten used in the setting should also be measured in surveillance. In such

cases, resistance to ethambutol could also be measured in surveillance. Thisis because ethambutol is the only rst-line oral agent or which susceptibilitycan be somewhat reliably tested, and which could be part o a treatment regi-

men or MDR-TB.

In summary, at a minimum, drug resistance surveillance should measure susceptibility to the

ollowing drugs:

a. Isoniazid and riampicin;

b. I resistance is detected to riampicin, then susceptibility to the uoroquinolones and

second-line injectable agents most oten used in the setting should also be tested. Testingor susceptibility to the rst-line drug ethambutol should also be considered.

Testing or susceptibility to other drugs should be considered based on perceiveduse in a setting, country capacity or testing, and known reliability o suscepti-bility results.

For urther guidance on selecting second-line drugs or DST, including

inormation on cross-resistance and known reliability and reproducibility osecond-line DST, see WHOPolicy guidance on drug-susceptibility testing (DST) o

second-line antituberculosis drugs (5).

3.4 Quality assurance o drug susceptibility testing

To ensure that results o DST are reliable, a comprehensive laboratory quality

assurance system is undamental. This system or DST should be designed tocontinuously monitor internal work practises, technical procedures, equipmentand materials (internal quality control), and to systematically assess laboratorycapabilities by using an external laboratory (external quality assessment).

3.4.1 ieal qaly cl

Standardized procedures and registers must be employed; whether the proportionmethod, resistance ratio method, absolute concentration method, liquid culturemethods, or other method is used or susceptibility testing and or ormulation omedia. As a part o internal quality control, the quality o the medium should be

controlled or each batch. Drugs added to the medium must be pure substances

1 It should be noted that riampicin resistance unaccompanied by isoniazid resistance is rare;

presence o such a phenomenon in more than 3% o TB cases is an indication that errors arelikely present in either riampicin or isoniazid testing.

2 Second-line injectable agents include kanamycin, amikacin, and capreomycin. Streptomycin isclassied as a rst-line injectable agent (Fourth edition o the WHO Guidelines or treatment otuberculosis (24)).


33/98


obtained rom a reputable rm, the percentage o potency must be clearly indi-cated, and they must be properly stored. Drug dilutions and their addition to themedium should be perormed in accordance with accepted standards.

For conventional solid culture methods, susceptibility testing should be per-

ormed on the standard H37Rv strain in each new batch o drug-ree and drug-containing medium. It is also recommended that this internal quality controlinclude a combination o strains with known resistance to two or three drugs,

but avoiding MDR and particularly XDR strains. Since medium batches will beconsumed quickly, it may be necessary to include these reerence strains witheach batch o survey strains processed or DST. Moreover, the usual internalquality assurance procedures or new batches o drug-ree and drug-containing

media apply, and results should always be validated by a supervisor who willascertain that all strains with doubtul results will be re-tested.

3.4.2 Exeal qaly assessme a e le e Spaaal reeece Labaynewk (SrLn)

External quality assessment is composed o several components: prociency

testing, rechecking o strains, and onsite evaluations o laboratories; all con-ducted in cooperation with a partner external laboratory.

The SRLN plays a critical role in capacity strengthening o laboratoriesworldwide, and is undamental in the external quality assessment activities that

ensure the accuracy o national surveillance o drug resistance. At the time opublication o these guidelines, there were 28 Supranational Reerence Labora-tories (SRLs) in the network (see Annex 2).

SRLs maintain a high level o quality by participating in annual intra-net-work prociency testing o DST. The SRLs judicially determine a consensus onthe susceptibilities o selected strains to rst-line drugs (isoniazid, riampicin,ethambutol, streptomycin) and, as o 2008, to second-line drugs (kanamycin,

amikacin, capreomycin, ofoxacin). The panels o strains are subsequently usedto assess the prociency o National Reerence Laboratories (NRLs), as well as

any subnational reerence laboratories that provide DST results or surveillancesystems and drug resistance surveys. SRLs can also provide onsite evaluations

o NRLs and training and supervision as necessary.External quality assessment o a NRLs accuracy at DST requires an exchange

o strains oM. tuberculosis in two directions: rom the SRL to the NRL, and

rom the NRL to the SRL:

From the SRL to the NRL (prociency testing): An NRL should annually receivea panel o coded strains rom a partner SRL to be tested or susceptibility to

rst-line and, i applicable, to second-line drugs. For each strain, the NRLindicates the susceptibility to each o the our rst-line drugs (as shown inAnnex 3A) and each o the selected second-line drugs (as shown in Annex3B). The NRL and SRL should agree beorehand on which second-line drugs


34/98


20

to test. The test results o the NRL should be compared with the coded resultso the judicial consensus o the SRLN, which can be considered a gold stand-ard. The procedure should be double-blinded.

The minimum required agreement should be dened or each drug and should

be at least 95% or isoniazid and riampicin. Sensitivity, specicity, and repro-ducibility o susceptibility testing are calculated or each o the our rst-linedrugs tested; a sample analysis sheet is shown in Annex 4A. I an NRL also

tests or susceptibility to second-line drugs, an additional analysis sheet is used,as shown in Annex 4B. Similar methodology can be applied or external qualityassessment rom the NRL to regional laboratories in countries where such lab-

oratories are also perorming susceptibility testing. Note: when applying to theGreen Light Committee Initiative (GLC) or access to high-quality second-lineanti-TB drugs at concessional prices or the treatment o MDR-TB, applicantsare asked or their latest prociency testing results.

From the NRL to the SRL (quality assessment o results, also known as recheck-

ing): In order to assure the quality o DST, a sample o strains isolated duringsurveillance should be sent to a partner SRL to be retested. The results should

be compared or agreement with respect to each drug. Sample analysis sheetsor rst-line drugs and second-line drugs are shown in Annexes 5A and 5B,respectively. For inormation on how rechecking should be included in thedesign o a survey, see section 6.4.4 Susceptibility testing, including rechecking.

In countries where exporting strains is not permitted, a rechecking exerciseshould take place with another laboratory participating in prociency testingexercises with an SRL. National and international rules and regulations and

turnaround times or shipment to the SRL must be considered or planningpurposes.

Quality assessment indicators or DST oMycobacte rium tube rculosis in the Supranational Reerence Laboratory Network

Sensitivity Ably eec e essace; .e. e pp essa sas aae eece

Specicity Ably eec e sscepbly; .e. e pp sscepblesas a ae eece

Efciency or Accuracy te pp al sas a ae cecly eece as begessa sscepble

Predictive value or resistance te pp al mease essace a s e essace

Predictive value or susceptibility te pp al mease sscepbly a s e sscepbly

Reproducibility or reliability ia-labay ageeme bewee plcae cles expesse as apeceage

At the time o publication, quality assurance systems or molecular and liquidmedia DST were being developed by WHO.


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21

4.

Etical considerations

4. Ethical considerations

Inormation obtained rom anti-tuberculosis drug resistance surveillance is cru-cial or planning a robust MDR-TB control programme. The overall goal o pub-

lic health activities is to promote a populations health, but the rights, reedom,privacy and condentiality o individual patients need to be respected as ar aspossible in planning and implementing a surveillance system or a survey (42).

Some activities can unambiguously be identied as research, and others as

routine surveillance, but there is a grey zone o activities that cannot easily beclassied as just one or the other. Research ethics and public health ethics aregrounded in similar principles, but the application o these principles will notalways be identical (43). In order to ensure adherence to ethical standards, sur-

vey protocols and new surveillance systems in the planning stage should bereviewed by ethics committees or institutional review boards. Such reviewsshould include due consideration o the ollowing key concepts or the ethical

conduct o surveillance (42, 44, 45):

Condentiality Sensitive patient inormation should be kept condential unlessits disclosure has been authorized by the person concerned. However, it may

be permissible to disclose some medical inormation without patient consentor legitimate public health purposes (or example, mandatory reporting ocertain inectious diseases). In practise, personal data should be shared and

revealed to others only as ar as strictly necessary or the unctioning o thesurveillance system and/or or the promotion o crucial public health goals.Unjustied disclosure o personal inormation would not only violate thepatients privacy, but could also oster stigma and discrimination.

Inormed consent In the course o a survey, inormed consent should beobtained rom individuals who have the capacity to make their own deci-sions, and consent should be obtained rom a surrogate decision-maker orincapacitated persons. Special care should be taken that marginalized groups

(e.g. children, women, prisoners, migrants, reugees, etc.) do not eel orcedor pressured to participate, and that they are protected against potential stig-ma resulting rom participating. In contrast to the usual practise in medical

research, obtainment o individual inormed consent is not usually neces-


36/98


22

sary or routine surveillance, especially when obtaining inormation rom anentire population is essential to achieving critical public health objectives.Even when obtaining individual consent is deemed unnecessary, individualsshould be given inormation about the nature and purposes o the surveil-

lance to the extent this is possible. Access to treatment In contrast with surveillance o standard tuberculosis

indicators, surveillance o drug-resistance in tuberculosis raises a particular

ethical dilemma when surveillance activities are conducted in settings wherethere is no capacity to properly treat patients that may be identied as hav-ing drug-resistant strains. The results o the testing should be communicated

to participants, and those in need should receive appropriate treatment withsecond-line anti-tuberculosis drugs. I appropriate treatment options are notavailable in a setting, the necessary measures to initiate an MDR-TB treat-ment programme should be planned in parallel with planning or a survey.

The national or regional TB control programme should consider preparing anapplication to the Green Light Committee (GLC) Initiative1 to gain access toquality-assured second-line drugs or the treatment o MDR-TB.

For assistance in developing an ethical review protocol or reviewing a MDR-TBsurveillance activity, contact the Global Project secretariat at [email protected]

1 In addition to enabling access to high-quality second-line anti-TB drugs at concessional prices

or the treatment o MDR-TB, the GLC ensures eective treatment o MDR-TB patients inaccordance with WHO Guidelines or the programmatic management o drug-resistant tuberculosis(25), and urthermore provides access to technical assistance to acil itate rapid scale-up oMDR-TB management. For more inormation, see http://www.who.int/tb/challenges/mdr/greenlightcommittee/en/.


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Part II.Ccg a svey


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25

5.

Surey planning

5. Survey planning

Conducting a drug resistance survey that will provide accurate, precise, andreliable results requires signicant planning. In order to obtain data that are

representative o the geographically-dened population under study, the samplemust be careully designed, and measures must be in place to ensure that thedata collected is properly categorized and the DST is based on quality-assuredbacteriology. All o this requires comprehensive and accurate planning o logis-

tics, including pre-survey budgeting o all planned expenses.

5.1 Setting specic objectives

A critical component o the initial planning process is to clearly identiy the

specic survey objectives in order to guide the development o a survey that willbe able to collect meaningul inormation. Specic objectives may include:

to determine the proportion o new TB cases in a geographical setting thathave resistance to selected rst-line anti-tuberculosis drugs;

to determine the proportion o previously treated cases in a geographicalsetting that have resistance to selected rst-line anti-tuberculosis drugs;

to determine the proportions and pattern o drug resistance to fuoro-quinolones and second-line injectable agents among strains with con-

rmed resistance to isoniazid and riampicin; to evaluate associations between drug resistance and age groups and sex; to evaluate associations between drug resistance and HIV status; to evaluate associations between drug resistance and country o origin; to speciate mycobacteria isolated rom sputum smear positive pulmonary

TB cases in the country; to establish the oundation or routine surveillance o drug resistance in

order to observe trends over time; to evaluate associations between drug resistance and risk actors including

history o incarceration, smoking, alcohol abuse and/or drug abuse.At the same time, conducting a survey can contribute to establishing or strength-ening a quality-assured laboratory network in a country.


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5.2 Development o a protocol and time schedule

A survey protocol should be developed that describes all aspects o the sur-

vey: the coordination team and individual members roles and responsibilities;objectives; sample size and design; logistics; training; ethical considerations;

laboratory capacity and quality assessment o drug susceptibility results; datamanagement; and budget. Once the diagnostic centres participating in the sur-

vey are identied by the chosen sampling method, a schedule can be established,taking into account logistics, climatic conditions, and the Central Reerence Lab-oratory workload. All laboratory methods and the system o quality assuranceshould be discussed and agreed with the partner SRL. Furthermore, the proto-

col should describe ethical issues, and the established timeline should take intoconsideration the time required or the protocol to receive necessary approval

rom relevant ethical review panels.A checklist or a survey protocol is included in Annex 6. WHO and other tech-nical partners can assist in the development o a survey protocol, and should beasked to review a survey protocol prior to initiation o a survey. This will ensurethat all requisites have been considered and described comprehensively, quality

control measures are in place, and the data collected would be representative othe geographically-dened population under study. Once nalized, such a pro-tocol should be distributed to all coordination team members and health ocersparticipating in the survey.

5.3 Minimum required acilities or a survey area

The country, state, province, or city selected to be a surveys geographical areashould have at least one quality-assured central laboratory or culture and DST(i.e. a Central Reerence Laboratory, which is usually the National ReerenceLaboratory) linked by mail or messenger with all intermediate TB laborato-

ries and the majority o TB diagnostic centres. I such a quality-assured centrallaboratory does not yet exist, the shipping o sputum specimens to an external

laboratory may be considered.

Diagnostic centres

Diagnostic centres include all institutions where decisions on diagnosis aremade and patients suspected o having TB are registered. Most diagnostic cen-

tres in TB control programmes with limited means are non-specialized healthcentres and clinics or outpatient departments o hospitals operated by the gov-ernment or by nongovernmental organizations. Private sector institutions andgeneral practitioners are not included in survey activities unless their activities

are based on some agreement with the national TB control programme (public-private mix initiatives), and they are ollowing national guidelines or diagnosisand treatment.


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275. Survey planning

A basic set o TB inection control measures should be implemented in allacilities involved in a drug resistance survey. In particular, attention should bepaid to control the spread o pathogens and minimize time patients suspected ohaving TB spend in health-care acilities.1

Diagnostic centres may or may not have the ability to conduct smear micro-scopy and culture. Quality-assured microscopy together with adequate reerralsystems or culture and DST are prerequisites or the implementation o a drug

resistance survey.

Central Reerence Laboratory

The Central Reerence Laboratory prepares cultures rom the sputum samples

received by the diagnostic centres, and undertakes the identication oM. tuber-

culosis strains, as well as DST. I there are intermediate culture laboratories in

the network, mycobacterial isolates, rather than sputum specimens, can be sentto the Central Reerence Laboratory or testing.

One o the main tasks o the Central Reerence Laboratory is to ensure thequality o smear microscopy, culture and DST perormed by regional or peri-pheral units by establishing a regular onsite supervision programme or those

units, and by providing training in, and quality assurance systems or, the lab-oratory procedures. An external quality assessment programme, organized incooperation with a partner SRL, will validate the results o susceptibility testsdone by the Central Reerence Laboratory.

Basic laboratory equipment and materials must be available and unctional inthe Central Reerence Laboratory beore the implementation o a survey. Drugresistance surveys should only be undertaken when the laboratories conductingculture and DST are sae, and appropriately equipped with trained sta work-

ing with clear standard operating procedures and producing quality-assureddata. Processing o specimens or culture and DST must be perormed underappropriate biosaety conditions, the guidelines or which are currently being

developed by WHO. It is important to note that drug resistance surveys will

heavily increase the workload o the reerence laboratory, and should only beundertaken where capacity is sucient.

5.4 Sampling o cases

Statistical methodology should be considered a undamental aspect o the

design o surveys that sample patients, and an experienced statistician shouldbe involved throughout the survey rom the early planning stages.

1 For more inormation see: WHO policy on TB inection control in health-care acilities, congregatesettings and households. Geneva, World Health Organization, 2009, (document WHO/HTM/TB/2009.419).


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5.4.1 deg e samplg ameThe sampling rame or a survey to measure the proportion o new cases (i.e.cases with a history o less than one month o previous TB treatment or no pre-vious TB treatment) having anti-tuberculosis drug resistance should include allnew sputum smear positive pulmonary TB patients in the setting.1

Surveys are usually based on smear positive TB cases or two reasons:

1. There is no strong evidence to indicate that the proportion o cases that have

drug resistance varies substantially according to whether the TB case is smearpositive or smear negative. However, HIV-inected cases with a higher likeli-hood o being paucibacillary or smear negative may be exposed to dierent

risk actors.

2. The culture yield rom smear negative patients is relatively low compared to

smear positive cases (46). Inclusion o cases with a low culture yield requires asignicantly larger sample size, and may increase laboratory workload up to 10times. Thereore, countries interested in including smear negative cases shouldstrongly consider the implications or logistics and laboratory capacity.

Sampling o previously treated cases

Accae evala essace pevsly eae cases pves ccal ma pgammemaageme, clg ma egme evelpme a evala. hweve, e esg a

epeseave svey amg pevsly eae cases s callegg. As pa e Glbal Pla StoP tB(20062015), esablsme e dSt all pevsly eae tB cases s a py, w e am allegs avg s capacy by 2015. i e meame, segs wee e dSt pevsly eaecases s ye easble, eally a sepaae, apppaely-sze sample pevsly eae cases sl beevse a s vey. hweve, ms se gs, eacg a sample sze calclae pevsly eae caseswl be easble e e small mbe pevsly eae cases e aally.

o e e a, smply ellg pevsly eae paes g e ake pe ew cases mayesl a sample sze a es allw a sfcely pecse esmae Mdr pevalece, e elkely small mbe pevsly eae cases elle. i s eee avsable exe e ake pe

pevsly eae cases bey e ake pe ew cases. te a sc a exes wllepe lcal esces a capacy, a cl seve as a bass esabls a gg svellace sysem pevsly eae cases. hweve, ay exes e ecme pevsly eae cases sl beecal acss all agsc cees selece as clses, ese a e sample emas gegapcallyepeseave. i e sample s sel-wege (pbably-ppal sze clse samplg), exess e ecme pevsly eae cases sl als be ecal acss clses.

1 In settings that conduct routine culture on all new cases, the sampling rame should include allnew culture-positive pulmonary TB patients in the setting.


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I a survey aims to determine the relative risk o drug resistant TB amongHIV-positive TB patients compared with HIV-negative TB patients, a morecomplex study design would be required, oten involving a much larger sam-ple size. Few countries have conducted such studies; thereore it is important

to seek appropriate technical support or advice on survey design and labora-tory needs when designing such a protocol.

The sampling rame should include, as a minimum, all patients registered inthe public sector under the NTP. Via established initiatives, patients treatedin health care acilities outside o the NTP could be included in the samplingrame.

5.4.2 Sample sze

For surveys measuring the proportion o new (not previously treated) cases thathave anti-tuberculosis drug resistance,1 the calculation o an appropriate samplesize should be based on the ollowing (47):

the total number o new sputum smear positive cases registered in the pre-vious year in the country or in the geographical setting to be studied;

expected proportion o resistance to riampicin2 rom available data (in the

absence o available data, the best guess o investigators should be used); the desired precision, meaning to what extent a measured proportion may

err on either side. As a general rule, precision corresponds to the percent-age o uncertainty one is willing to accept. For example, an absolute preci-

sion o 0.01 would give a proportion within one percentage point (1%) othe actual proportion o riampicin resistance. The precision value shouldbe as low as possible, while ensuring that obtaining the calculated sample

is logistically easible. However, it should never should be more than 20%o the value o the expected proportion o riampicin resistance. For exam-ple, i riampicin resistance is expected to be 4%, then precision should beno more than 0.8% (an absolute precision o 0.008);

a condence interval o 95% should be used or the measured proportion.

The ollowing ormula can be used to calculate the sample size under simple

random sampling (SRS), with nite population correction:

n(SRS) = N*z2 *p * (1 p)

d2 * (N 1) +z2 *p * (1 p)

1 An analogous calculation should be considered or previously treated cases, i routine DST osuch cases is not yet established.

2 Resistance to riampicin can serve as a proxy or MDR-TB.

5. Survey planning


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where:

N = total number o new smear positive cases registered during one year in thecountry;

z = z-value (rom the standard normal distribution) that corresponds to the

desired condence level (i condence interval = 95%, z = 1.96);d = absolute precision (as a decimal, e.g. 0.01 or 0.02);p = expected proportion o riampicin resistance in the target population (as a

decimal, e.g. 0.05 or 0.15).

I the cluster sampling method is adopted, the cluster design eect needs to

be taken into account. Unless the cluster design eect can be estimated romprevious surveys, an eect o 2 should be assumed (which is realistic, but err-ing on the side o being conservative), and thereore, the calculated sample size

obtained rom the equation above needs to be multiplied by 2.Finally, the calculated sample size needs to be increased by 1520% to account

or expected losses. Losses include patients diagnosed as smear positive whodo not return to the diagnostic centres or do not produce an adequate sampleor the survey, patients whose culture is contaminated or does not grow, and

patients whose susceptibility testing does not give interpretable results (unread-able or too ew colonies).

Countries that repeat a survey should aim to document dierences in the

proportion o patients with drug resistance in comparison with previous sur-

veys. Thereore, the sample size should be calculated so it can detect a signi-cant dierence in the proportions o riampicin resistance ound in the previoussurvey, and anticipated in the current survey. The sample size then depends on

the expected dierence and the power o the comparative test. The smaller thedierence to detect between the proportions, the larger the sample size. Theassistance o a statistician is needed to determine an appropriate sample size ora subsequent survey.

5.4.3 Samplg saegesDierent sampling strategies can be adopted to select a sample o TB patientsrepresentative o all TB patients in a geographic setting. In order to select a rep-resentative group o newly registered patients, a randomization step is essential(48, 49). Simple random sampling o individual patients is not practical in TB

diagnostic centres. This is mainly because routines that are usually identical ormost patients would be disrupted, and compliance o sta and patients wouldconsequently be low and the quality o data poor. Involving all diagnostic cen-

tres can also give rise to logistic problems and high costs. Randomization can

take place at the level either o diagnostic centres or possibly o health districts.In

Documents

Guidelines for Survelaince of Drug Resistance in TB