Systematic reviews of health promotion and
public health interventions
Rebecca Armstrong
Elizabeth Waters
Cochrane Health Promotion & Public Health Field
Overview
Overview of systematic reviews Outline of The Cochrane Collaboration Role of the HPPH Field Function of systematic reviews in informing
policy and practice Key elements of systematic reviews
Asking answerable questions Searching for evidence Assessing quality Synthesising results Applicability and transferability
Meta-analysis
Systematic reviews
Reviews(narrative/literature/traditional)
Types of reviews
Narrative reviews
Usually written by experts in the fieldUse informal and subjective methods to
collect and interpret informationUsually narrative summaries of the
evidence
Read: Klassen et al. Guides for Reading and Interpreting Systematic Reviews. Arch Pediatr Adolesc Med 1998;152:700-704.
What is a systematic review?
A review of the evidence on a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant primary research, and to extract and analyse data from the studies that are included in the review*
*Undertaking Systematic Reviews of Research on Effectiveness. CRD’s Guidance for those Carrying Out or Commissioning Reviews. CRD Report Number 4 (2nd Edition). NHS Centre for Reviews and Dissemination, University of York. March 2001.
Key elements of a systematic review
Structured, systematic process involving several steps :
1. Formulate the question2. Plan the review3. Comprehensive search4. Unbiased selection and abstraction process5. Critical appraisal of data6. Synthesis of data (may include meta-analysis)7. Interpretation of results
All steps described explicitly in the review
Systematic vs. Narrative reviews
Scientific approach to a review article
Criteria determined at outset
Comprehensive search for relevant articles
Explicit methods of appraisal and synthesis
Meta-analysis may be used to combine data
Depend on authors’ inclination (bias)
Author gets to pick any criteria
Search any databases
Methods not usually specified
Vote count or narrative summary
Can’t replicate review
Advantages of systematic reviews
Reduce biasReplicabilityResolve controversy between conflicting
studiesIdentify gaps in current researchProvide reliable basis for decision making
Limitations of systematic reviews specific to health promotion
Results may still be inconclusiveThere may be no trials/evidenceThe trials may be of poor qualityThe intervention may be too complex to be
tested by a trialPractice does not change just because
you have the evidence of effect/effectiveness
Consider these interventions…
Interventions to promote smoke alarm ownership and functionSchool-based driver education for the prevention of traffic crashesHelmets for preventing head and facial injuries in bicyclists
Do you think the results identified in SRs will be good, promising or absent (and potentially harmful)?
Results from systematic reviews
Helmets reduce bicycle-related head and facial injuries for bicyclists of all ages involved in all types of crashes including those involving motor vehicles.
The results provide no evidence that drive education reduces road crash involvement, and suggest that it may lead to a modest but potentially important increase in the proportion of teenagers involved in traffic crashes.
Results from this review suggest that area-wide traffic calming in towns and cities may be a promising intervention for reducing the number of road traffic injuries and deaths. However, further rigorous evaluations of this intervention are needed.
The Cochrane Collaboration
International non-profit organisation that prepares, maintains, and disseminates systematic up-to-date reviews of health care interventions
Cochrane Collaboration
Named in honour of Archie Cochrane, a British researcher
In 1979:
“It is surely a great criticism of our profession that we have not organised a critical summary, by specialty or subspecialty, adapted periodically, of all relevant randomised controlled trials”
The Cochrane Library
Cochrane Systematic reviews : Cochrane reviews and protocols
Database of Reviews of Effects: Other systematic reviews appraised by the Centre for Reviews and Dissemination.
Cochrane Central Register of Controlled Trials:
Bibliography of controlled trials (some not indexed in MEDLINE).
Health Technology Assessment Database: HTA reports
NHS Economic evaluation database:
Economic evaluations of health care interventions.
The Cochrane Library
www.thecochranelibrary.com
Cochrane HPPH Field
Represent the needs and interests of those in health promotion and public health in Cochrane matters
Represent Cochrane in health promotion and public health forums
In transition from Field to Review Group Will edit PH reviews for the Cochrane Library
Cochrane Collaboration Structure
Steering Group
Review Groups
Centres Fields
Methods GroupsConsumer Network
Collaborative Review Groups (50)
Produce systematic reviews relevant to a particular disease or health issue for inclusion in the Cochrane Library
Examples Airways Group Drug and Alcohol Group Heart Group Injuries Group Skin Group Pregnancy and Childbirth Group Stroke Group Breast Cancer Group
Methods Groups (12)
Provide advice and support in the development of the methods of systematic reviews
Examples Non-Randomised Studies Screening and Diagnostic Tests Empirical Methodological Studies Qualitative Methods
Cochrane Centres (14)
Work to assist all Cochrane entities within a specific geographical area
Examples Australasian Cochrane Centre (at Monash) South African Cochrane Centre Italian Cochrane Centre Chinese Cochrane Centre
Cochrane Fields/Networks (9)
Represent an area of interest which spans a number of health problems - and hence a number of Review Groups
Examples Health Promotion and Public Health Field Primary Health Care Field Cancer Network Child Health Field
Cochrane HPPH Field
Cochrane Fields represent a population group, or type of care that overlaps multiple Review Group areas
HPPH Field Registered in 1996 Administered from Melbourne Funded by VicHealth Over 400 members on contact database across
>30 countries
Staff
Elizabeth Waters (Director) Jodie Doyle (Coordinator) Rebecca Armstrong (Senior Research Fellow) Naomi Priest (Research Fellow)
Asking an answerable Asking an answerable questionquestion
Questions of interest
Effectiveness: Does the intervention work/not work? Who does it work/not work for?
Other important questions: How does the intervention work? Is the intervention appropriate? Is the intervention feasible? Is the intervention and comparison relevant?
Answerable questionsAnswerable questions
EFFECTIVENESS
A description of the populations P
An identified intervention I
An explicit comparison C
Relevant outcomes O
A PICO questionA PICO question
Time-consuming question:
What is the best strategy to prevent smoking in young people?
An answerable questionAn answerable question
Q. Are mass media (or school-based or community-based) interventions effective in preventing smoking in young people?
Problem, population
Intervention Comparison Outcome Types of studies
Young people under 25 years of age
a) Televisionb) Radioc) Newspapers d) Bill boardse) Postersf) Leafletsg) Booklets
a) School-based interventions
b) No intervention
a) objective measures of smoking (saliva thiocyanate levels, alveolar CO)
b) self-reported smoking behaviour
c) Intermediate measures (intentions, attitude, knowledge, skills)
d) Media reach
a) RCT
b) Controlled before and after studies
c) Time series designs
The PICO(T) chartThe PICO(T) chart
Finding the evidenceFinding the evidence
Systematic review processSystematic review process
1. Well formulated question
2. Comprehensive data search
3. Unbiased selection and abstraction process
4. Critical appraisal of data
5. Synthesis of data
6. Interpretation of results
A good searchA good search
Clear research question Comprehensive search
All domains, no language restriction, unpublished and published literature, up-to-date
Document the search (replicability)
Components of electronic searching
1. Describe each PICO component2. Start with primary concept3. Find synonyms
a) Identify MeSH / descriptors / subject headingsb) Add textwords
4. Add other components of PICO question to narrow citations (may use study filter)
5. Examine abstracts6. Use search strategy in other databases
(may need adapting)
So you want to do a ‘quick & dirty’?
DARE CENTRAL PubMed (clinical queries, related records) CDC NICE Organisations who do work in your area …google
The Cochrane Library: The Cochrane Library: www.thecochranelibrary.comwww.thecochranelibrary.com
Cochrane HPPH Field
Health-evidence.ca
The Guide to Community Preventive Services
http://www.thecommunityguide.org/
National Institute for Health and Clinical Excellence
http://www.publichealth.nice.org.uk/page.aspx?o=home
Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre)
http://eppi.ioe.ac.uk
Effective Public Health Practice Project (EPHPP)
http://www.myhamilton.ca/myhamilton/CityandGovernment/HealthandSocialServices/Research/EPHPP/
Centre for Reviews and Dissemination
http://www.york.ac.uk/inst/crd
Other sources of primary researchOther sources of primary research
Searching
www.google.com.au The order of terms will effect the results so
start with the obvious or key concept No need for ‘and’ Google will ignore common words
If they are important use + (e.g. policy + 3) Phrase searching is useful eg “suicide
prevention” Google searches for variations on words eg
diet, dietary
Searching
Where terms have multiple meanings you can direct google to remove sites you want to avoid (e.g. bass –music)
Keep your search strings brief Mental health promotion initiatives to prevent suicide
in young people
Compartmentalise your search strings “mental health promotion” suicide “Suicide prevention” “young people” Prevention and suicide and youth
Searching
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi Use the same principles for google – keep it
short and sweet. Key features
Journals DatabaseMeSH DatabaseSingle Citation MatcherClinical Queries
Searching
Searching
Searching
Select the Limits tab – just under the search string
Searching
These next few slides show you how to search MeSH terms in PubMed. Useful if you don’t have access to electronic databases. You combine this method with the one for text words outlined above. The process for combining text words and MeSH terms is outlines below.
ExampleExample
Mass media interventions to prevent smoking in young people
P= Young people
STEP ONE:STEP ONE:Find MeSH and textwords to
describe young people
ExampleExample
Mass media interventions to prevent smoking in young people
P= Young people
MeSH: Adolescent
Child
Minors
ExampleExample
Mass media interventions to prevent smoking in young people
P= Young people
Textwords: Adolescent GirlChild BoyJuvenile TeenagerYoung people Young adultStudent Youth
Textwords
Truncation $:
To pick up various forms of a word
Teen$.tw Smok$.twTeenage Smoke
Teenager Smoking
Teenagers Smokes
Teens Smoker
Teen Smokers
Textwords
Wild cards ? and #:
To pick up different spellings
Colo?r.tw (? Can be substituted for one or no characters)
Colour
Color
Wom#n.tw (# Substitutes for one character)
Woman
Women
Textwords
Adjacent ADJn: retrieves two or more query terms within n words of each other, and in any order Great when you are not sure of phraseologyEg sport adj1 policy
Sport policyPolicy for sport
Eg mental adj2 healthMental healthMental and physical health
Example continuedExample continued
Mass media interventions to prevent smoking in young people
I = Mass media interventions
STEP TWO:STEP TWO:Find MeSH and textwords to
describe mass media interventions
Example continuedExample continued
MeSH Mass media Audiovisual aids Television Motion pictures Radio Telecommunications Newspapers Videotape recording Advertising
Example continuedExample continued
Mass media interventions to prevent smoking in young people
O = Prevention of smoking
STEP THREE:STEP THREE:Find MeSH and textwords to
describe prevention of smoking
Example of searchExample of search
P = YOUNG PEOPLEP = YOUNG PEOPLE
MeSHMeSH TextwordsTextwords
……………………………………………….. ……………………….……………………….……………………….………………………. ……………………….……………………….
……………………………………………….. ……………………….……………………….
I = MASS MEDIAI = MASS MEDIA
MeSHMeSH TextwordsTextwords
……………………………………………….. ……………………….……………………….……………………….………………………. ……………………….……………………….
……………………………………………….. ……………………….……………………….
C = (if required)C = (if required)
O = PREVENTION OF SMOKINGO = PREVENTION OF SMOKING
MeSHMeSH TextwordsTextwords……………………………………………….. ……………………….……………………….
……………………….………………………. ……………………….……………………….……………………………………………….. ……………………….……………………….
OROR
OROR
OROR
PP
ANDAND
II
ANDAND
CC
ANDAND
OO
Different bibliographic databasesDifferent bibliographic databases
Databases use different types of controlled vocabulary Same citations indexed differently on
different databases Medline and EMBASE use a different
indexing system for study type PsycINFO and ERIC do not have specific
terms to identify study typesNeed to develop search strategy for each database
Study design filters
RCTs See Cochrane Reviewer’s Handbook
Non-RCTs Not yet developed, research in progress
Qualitative research Specific subject headings used in CINAHL, ‘qualitative research’
used in Medline CINAHL Filter: Edward Miner Library
http://www.urmc.rochester.edu/hslt/miner/digital_library/tip_sheets/Cinahl_eb_filters.pdf
Systematic reviews/meta-analyses CINAHL: as above Medline
http://www.urmc.rochester.edu/hslt/miner/digital_library/tip_sheets/OVID_eb_filters.pdf
Medline and Embasehttp://www.sign.ac.uk/methodology/filters.html
PubMed
2. Unpublished literature2. Unpublished literature
Not all known published trials are identifiable in Medline (depending on topic)
Only 25% of all medical journals in Medline Non-English language articles are under-
represented in Medline (and developing countries)
Publication bias – tendency for investigators to submit manuscripts and of editors to accept them, based on strength and direction of results (Olsen 2001)
2. Unpublished literature2. Unpublished literature
Hand searching of key journals and conference proceedings
Scanning bibliographies/reference lists of primary studies and reviews
Contacting individuals/agencies/ academic institutions
Neglecting certain sources may result in reviews being biased
Librarians are your friends!Librarians are your friends!
Principles of critical Principles of critical appraisalappraisal
Critical appraisalCritical appraisal
The process of systematically examining research evidence to assess its validity, results and relevance before using it to inform a decision.
Alison Hill, Critical Appraisal Skills Programme, Institute of Health
Sciences, Oxford http://www.evidence-based-medicine.co.uk
Critical appraisal I: Critical appraisal I: Quantitative studiesQuantitative studies
Why appraise validity?Why appraise validity?
Not all published and unpublished literature is of satisfactory methodological rigour Just because it is in a journal does not mean it
is sound! Onus is on you to assess validity!
Quality may be used as an explanation for differences in study results
Guide the interpretation of findings and aid in determining the strength of inferences
Bias – quality assessment toolBias – quality assessment tool
1. Selection bias
2. Allocation bias
3. Confounding
4. Blinding (detection bias)
5. Data collection methods
6. Withdrawals and drop-outs
7. Statistical analysis
8. Intervention integrity
Recruit participants
Allocation
Exposed to intervention
Not exposed to intervention
Follow-upFollow-up
Outcome Outcome
Allocation of concealment
Blinding of outcome assessment
Intention-to-treat
Withdrawals
Data collection methods
Selection bias
Integrity of intervention
Intervention Control
Analysis AnalysisStatistical analysis
Confounding
Critical appraisal tools
RCTs The Quality Assessment Tool for Quantitative
Studies (http://www.city.hamilton.on.ca/PHCS/EPHPP/).
Non-RCTs Cochrane Effective Practice and Organisation
of Care Group (http://www.epoc.uottawa.ca/). The Berkeley Systematic Reviews Group
(http://www.medepi.net/meta/)
Critical appraisal II: Critical appraisal II: Qualitative studiesQualitative studies
Qualitative researchQualitative research
… explores the subjective world. It attempts to understand why people behave the way they do and what meaning experiences have for people.
Qualitative studies of experienceProcess evaluation
Undertaking Systematic Reviews of Research on Effectiveness. CRD’s Guidance for those Carrying Out or Commissioning Reviews. CRD Report Number 4 (2nd Edition). NHS Centre for Reviews and Dissemination, University of York. March 2001.
CASP appraisal checklistCASP appraisal checklist
1. Clear aims of research (goals, why it is important, relevance)
2. Appropriate methodology (what, how, why)3. Sampling strategy4. Data collection5. Relationship between researcher and
participants6. Ethical issues7. Data analysis8. Findings9. Value of research (context dependent)
Other qualitative checklistOther qualitative checklist
Quality framework Government Chief Social Researcher’s Office,
UK http://www.strategy.gov.uk/files/pdf/Quality_framew
ork.pdf
19 question checklist for process evaluations (EPPI-Centre)
Appraisal of a systematic reviewAppraisal of a systematic review
10 questions1. Clearly-focused question2. The right type of study included3. Identifying all relevant studies4. Assessment of quality of studies5. Reasonable to combine studies6. What were the results7. Preciseness of results8. Application of results to local population9. Consideration of all outcomes10. Policy or practice change as a result of evidence
CASP
Interpretation of resultsInterpretation of results
Factors influencing effectivenessFactors influencing effectiveness
Type III error (integrity of intervention)Theoretical framework of interventionContext
For whom did the intervention work, why, in what circumstances, at what cost
Difficulties addressing inequalitiesDifficulties addressing inequalities
Studies rarely present information on differential effects of interventions
Cannot locate studies addressing inequalities
May need original data from authorsLow power to detect subgroup differences
Integration of evidence into Integration of evidence into practicepractice
Assessing the applicability and transferability of interventions
Applicability – whether the intervention process could be implemented in the local setting, no matter what the outcome is. Is it possible to run this intervention in this local
setting? Eg. provision of condoms in area where they
are not acceptable for religious reasons
Wang et al 2005
Assessing the applicability and transferability of interventions
Transferability – if the intervention were to be implemented in the local setting, would the effectiveness of the program be similar to the level detected in the study setting? E.g. if the interventionists lack experience and
have few skills in delivering the intervention then its effectiveness in the local setting may be lower than that demonstrated in the study setting
Wang et al 2005
Review of questions proposed by Wang et al
Contact details
Rebecca Armstrong [email protected] 03 9667 1336 If I can’t help you I might be able to point you in
the right direction. If you are interested in training and support for
conducting SRs or increasing uptake within your organisation, region, state please let me know