Vol. - No. - - 2014 Journal of Pain and Symptom Management 1

Original Article

Development and Validation of theBreakthrough Pain Assessment Tool (BAT) inCancer PatientsKatherine Webber, MBBS, Andrew N. Davies, FRCP,Giovambattista Zeppetella, FRCP, and Martin R. Cowie, MD, MScImperial College London (K.W., A.N.D., M.R.C.), London; Royal Surrey County Hospital (K.W.,

A.N.D.), Guildford; Royal Marsden Hospital (K.W.), London; and St. Clare Hospice (G.Z.),

Hastingwood, United Kingdom

Abstract

Context. The successful management of breakthrough pain depends on a

combination of adequate assessment, appropriate (individualized) treatment,and adequate re-assessment. Currently, there is no fully validated clinicalassessment tool for breakthrough pain in cancer patients.

Objectives. The aim of this project was to develop and validate a breakthroughpain assessment tool (the BAT) for use in the clinical setting.

Methods. The content of the BAT was determined by reviewing the medicalliterature, conducting a Delphi process with experts in breakthrough pain and/orpain assessment and conducting semi-structured interviews with cancer patientswith breakthrough pain. The tool was then subjected to a series of standardpsychometric tests to assess its factor structure, validity (i.e., content validity,construct validity), reliability (i.e., internal consistency, test-retest reliability), andresponsiveness to change.

Results. The BAT comprised two pages with 14 questions. Factor analysisconfirmed the presence of two underlying factors. Psychometric testing confirmedthat the tool is valid, reliable, and responsive to change.

Conclusion. This study provides initial evidence for the validity and reliability ofthe breakthrough pain assessment tool which may be used to facilitate themanagement of patients with breakthrough cancer pain in the clinicalsetting. J Pain Symptom Manage 2014;-:-e-. � 2014 U.S. Cancer Pain ReliefCommittee. Published by Elsevier Inc. All rights reserved.

Key Words

Breakthrough pain, episodic pain, cancer, pain assessment

Address correspondence to: KatherineWebber, MBBS, Im-perial College London and Royal Surrey County Hos-pital, Egerton Road, Guildford, Surrey, GU2 7XX,United Kingdom. E-mail: kath@kathwebber.com

Accepted for publication: October 30, 2013.

� 2014 U.S. Cancer Pain Relief Committee.Published by Elsevier Inc. All rights reserved.

0885-3924/$ - see front matterhttp://dx.doi.org/10.1016/j.jpainsymman.2013.10.026

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IntroductionBreakthrough pain has been defined as ‘‘a

transient exacerbation of pain that occurseither spontaneously, or in relation to a spe-cific predictable or unpredictable trigger,despite relatively stable and adequatelycontrolled background pain.’’1 Breakthroughpain is common in patients with cancer pain(40%e80%).2 The clinical features vary fromindividual to individual and may vary withinan individual over time.3 Nevertheless, break-through pain is often reported to be frequentin occurrence, acute in onset, short in dura-tion, and moderate-to-severe in intensity.Moreover, the presence of breakthrough painoften has a significant negative impact on theactivities of daily living.4e7

The successful management of break-through pain depends on a combination ofadequate assessment, appropriate (individual-ized) treatment, and adequate re-assessment.1

The assessment of pain primarily depends onbasic clinical skills, that is, taking a detailed his-tory and performing a thorough examination.Assessment tools are routinely used in researchand are increasingly being used in day-to-dayclinical practice. Thus, the use of assessmenttools is associated with improvements in paincontrol.8 The ideal assessment tool is ‘‘user-friendly,’’ reflects the multidimensional aspectsof pain (and specifically the relevant painstate), is valid, is reliable, and is responsive tochange. Generic cancer pain assessment toolsare ill-suited to the assessment of breakthroughpain because they fail to assess the temporalcharacteristics that are unique to breakthroughpain, for example, duration and frequency ofbreakthrough episodes and the presence ofprecipitating factors (fundamental to the man-agement of breakthrough pain).

Portenoy and Hagen developed the Break-through Pain Questionnaire (BPQ) to specif-ically assess breakthrough pain.9 The tool wasdeveloped in an ad hoc manner, using theprinciples of cancer pain assessment and thereported characteristics of breakthrough can-cer pain. BPQ has not been formally validated,although it has been used in a number of clin-ical studies.5,6 Of note, BPQ has evolved overthe years (R. Portenoy, personal communica-tion). Subsequently, Hagen et al. developedthe Alberta Breakthrough Pain Assessment

Tool (ABPAT) to specifically assess break-through pain in the research setting (ratherthan the clinical setting).10 The tool was devel-oped in a more formal manner, with inputfrom both patients and experts in the field.The ABPAT has been validated to a limited de-gree and is currently undergoing further inves-tigation/validation. However, the length of theABPAT (22 pages) precludes its use in theassessment of breakthrough pain in day-to-day practice.11

The aim of this project was to develop, inaccordance with international guidelines,12e14

a brief, multidimensional, valid, reliable, andresponsive breakthrough cancer pain assess-ment tool for use by health care professionalsworking in various clinical settings (i.e., hospi-tal, hospice, community).

MethodsThe study was conducted at the Royal Mars-

denHospital (Sutton), St. Luke’s Cancer Centre(Guildford), and St. Clare Hospice (Hasting-wood) in the United Kingdom. The study wassponsored by Imperial College London, andethical approval was obtained from the RoyalMarsden Hospital Research Ethics Committee.The study was conducted in accordance withthe Declaration of Helsinki, Good Clinical Prac-tice, and local governance procedures.The subjects were recruited from the inpa-

tient and outpatient populations at the threestudy centers. The subjects were given an infor-mation sheet about the study and the opportu-nity to ask questions about the study and askedto sign a consent formbefore entering the study.

Development of the Assessment ToolThe content of the assessment tool was

developed in accordance with publishedguidelines from expert advisory and interna-tional regulatory bodies.12e14 Thus, a sequen-tial, multisource (expert and patientopinions), multimodal (qualitative and quanti-tative methods) process was used to ensurethat content of the assessment tool was rele-vant to the clinical scenario. Initially, a litera-ture review was undertaken to generate a listof items that could be used to characterizebreakthrough pain; the literature review iden-tified 37 potential items for inclusion in the

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assessment tool. Next, 14 experts from theU.K. evaluated these breakthrough pain itemsfor relevance, and importance, in the assess-ment of breakthrough pain. An ‘‘expert’’ wasdefined as a physician with specialist expertisein breakthrough pain and/or pain instrumentdevelopment and viewed by their peers as a keyopinion leader. The experts were asked to ratethe relevance of each of the items on a 5-pointLikert scale (strongly agree, agree, no prefer-ence, disagree, strongly disagree); items wereretained if at least 75% of the expertsagreed/strongly agreed that the item was rele-vant (Delphi process).

Subsequently, semistructured interviews wereundertaken with 10 patients with breakthroughpain to ensure their experiences were repre-sented within the assessment tool; purposivesampling was used to ensure patients with arange of gender, ages, and cancer diagnoseswere included. Content analysis was used toorganize data and identify recurring themesfrom the interviews.15 The results of the inter-views have been published elsewhere.16

The research group then drafted the ques-tions and response formats for each of the itemsto be included in the prototype assessment tool.Each question was worded as simply as possible,and in some cases, the patients’ own words wereuse to phrase the questions. The experts weresent the prototype and asked to comment onthe questions and response formats in termsof wording, clarity, relevance, and representa-tiveness. The prototype was revised on the basisof the feedback from the experts.

The revised prototype was then given to aconvenience sample of nine patients withbreakthrough pain to assess readability andclarity. A cognitive testing technique wasused, which encouraged patients to explaintheir thought processes as they completedthe assessment tool (so-called ‘‘think aloud’’methodology).17 If a problem was encoun-tered on more than one occasion, then theitem was revised in such a way to overcomethe problem. The final version of the Break-through Cancer Pain Assessment Tool (BAT)is shown in Appendix 1.

Psychometric Testing of the Assessment ToolThe inclusion criteria for this phase of the

study were 1) age older than 18 years, 2) cancer-related pain, 3) cancer-related breakthrough

paindexpert determined using a recommendeddiagnostic algorithm,1 4) regular/‘‘around-the-clock’’ analgesia during the previous week, and5) ability to complete the study protocol.

The protocol involved a maximum of threeassessments:

- Assessment 1: the subjects were asked tocomplete the BAT and a series of questionsabout the adequacy of breakthrough paincontrol (‘‘yes’’ or ‘‘no’’) and the need forchanges in management (‘‘yes’’ or ‘‘no’’).In addition, subjects were asked to completethe Brief Pain Inventory (BPI).18 The sub-jects were assessed by a clinician with an in-terest in breakthrough cancer pain; theclinicians also were asked a series of ques-tions about the adequacy of breakthroughpain control (‘‘yes’’ or ‘‘no’’) and anychanges in management/referral for otherinterventions (‘‘yes’’, ‘‘no’’; if yes, whatchanges?). Demographic information (e.g.,age, gender), and clinical information(e.g., cancer diagnosis, performance status),also were recorded during this assessment.

- Assessment 2 (conducted 24 hours afterAssessment 1): the subjects were askedto again complete BAT to assess the test-retest reliability of the instrument.

- Assessment 3 (conducted at least oneweek after Assessment 1): this assessmentwas similar to Assessment 1, althoughboth the subject and the clinician wereasked to comment on any change in thebreakthrough pain in the interveningperiod (i.e., ‘‘better’’, ‘‘same’’, ‘‘worse’’).

The current analgesic regimen was recordedat each assessment, particularly the usage ofrescue (‘‘breakthrough’’) medication.

InstrumentThe BAT comprises of 14 questions; nine of

the questions relate to the pain per se, and fivequestions relate to the pain treatment(Appendix 1). Graphical numerical ratingscales (NRSs) are used in six questions, cate-gorical scales in three questions, free text infour questions, and the remaining questionnecessitates the patient to mark the site ofthe pain on a body-shape outline.

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The BAT was compared with certain ques-tions from the Brief Pain Inventory (BPI),18 avalidated generic pain assessment tool, whichincludes four questions related to pain intensityand seven questions related to interferencewith function. The pain intensity items ask thepatient to rate their current pain, worst pain,average pain, and least pain on a 0e10 NRS,with 0 ¼ ‘‘no pain’’ and 10 ¼ ‘‘pain as bad asyou can imagine.’’ The pain severity index iscalculated by adding the four responses. Thepain interference items ask the patient to ratehow much the pain interferes with their gen-eral activity, enjoyment of life, mood, walking,work, relations with others, and sleep; the ques-tions again use a 0e10 NRS, with 0 ¼ ‘‘does notinterfere’’ and 10¼ ‘‘completely interferes.’’ Aninterference index is calculated by adding theinterference item scores. In addition, there isone question where the patient is required torate the percentage of pain relief provided bytheir pain treatment (0% ¼ ‘‘no relief’’ and100% ¼ ‘‘complete relief’’).

Statistical AnalysisPsychometric Testing. The BAT was evaluatedaccording to well-established methods andstandards (psychometric testing).19e22 Table 1summarizes the psychometric tests and outlinesthe statistical methods/criteria used to assessthe validity and reliability of the BAT. Thedata were analyzed using IBM SPSS, version19 (IBM Corp., Armonk, NY).

Sample Size. A sample size of 50 was requiredfor correlative analysis (test-retest reliabilityand convergent validity) to detect a clinicallyacceptable level of correlation (0.85) with80% power and a significance level of 5%.19

The sample size required for known clinicalgroup analysis was 70, based on previouslypublished interference scores in groups of pa-tients with breakthrough pain.5,19,23 Thus, anoverall sample size of 100 was determined, ac-counting for predicted high levels of patientattrition.

ResultsOne hundred subjects participated in the psy-

chometric testing of the BAT (Table 2). Forty-four patients did not complete Assessment 2;

the reasons for not completing this assessmentwere inability to contact patient (n ¼ 39) andpatient too unwell to complete assessment(n¼ 5). However, 81 patients completed Assess-ment 3; the reasons for not completing thisassessment were death (n ¼ 5), patient too un-well to complete assessment (n ¼ 7), patientwithdrew from study (n ¼ 2), and patient lostto follow-up (n ¼ 5). It took most patients5e10 minutes to complete the BAT.

Item Analysis/ReductionNone of the item coefficient correlations were

>0.75 indicating that none of the questionswere analogous to any of the other questions(and so none was a ‘‘redundant’’ question).The questions loaded onto one of two factors(Table 3):

- A breakthrough pain severity and impactfactor (i.e., ‘‘How often do you get break-through pain?;’’ ‘‘How severe is your worstepisode of breakthrough pain?;’’ ‘‘How se-vere is a typical episode of breakthroughpain?;’’ ‘‘Howmuchdoes the breakthroughpain distress you?;’’ ‘‘How much does thebreakthrough pain stop you from living anormal life?;’’ ‘‘How much do the side ef-fects from the painkiller for your break-through pain bother you?’’).

- A breakthrough pain duration and medi-cation efficacy factor (i.e., ‘‘How longdoes a typical episode of breakthroughpain last?;’’ ‘‘How effective is the painkillerthat you take for your breakthroughpain?;’’ ‘‘How long does the painkillertake to have a meaningful effect?’’).

ReliabilityThe Cronbach’s alpha coefficient for the

BAT as a whole was 0.70. The values for theseparate factors were 0.75 (breakthroughpain severity and impact factor; six items)and 0.55 (breakthrough pain duration andmedication efficacy factor; three items). Theintraclass correlation coefficient (test-retestreliability) was 0.88 for the BAT, 0.8 for thebreakthrough pain severity and impact factor,and 0.92 for the duration and medication effi-cacy factor.

Table 1Psychometric Tests Used to Assess the Validity and Reliability of Breakthrough Pain Assessment Tool

Psychometric Property Description Criteria Adopted

Item analysis/reduction The purpose of these analyses were toidentify common themes (‘‘factors’’)within the BAT and also identifyredundant questions (‘‘items’’).

Analysisdprincipal component analysis(calculation of eigenvalues; scree plotof eigenvalues; calculation of factorloading; oblique factor rotation).

Factors with an eigenvalue >1.0 indicatethemes to be retained.

Items with a factor loading >0.3 indicateimportant questions (for the theme).

Items with a correlation coefficient >0.75indicate analogous questions.19

ReliabilityInternal consistency The purpose of these analyses were to

ensure that items/sets of itemscorrelate with the remainder of thequestionnaire.

Analysisdcalculation of Cronbach alphacoefficients.

Cronbach alpha coefficients >0.7indicate good internal consistency (or>0.5 for scales of less than 5 items).21

Test-retest reliability The purpose of these analyses was toensure that the underlying construct isstable and that the results obtained onone occasion are similar to thoseobtained on another occasion (i.e., 24hours later).

Analysisdcalculation of intraclasscorrelation coefficients.

Intraclass correlation coefficients >0.8indicate good test-retest reliability.19

ValidityContent validity See text re-development of the BAT See text re-development of the BATConstruct validity:

Known group analysis/hypothesistesting

The purpose of these analyses was todetermine the ability of the BAT todifferentiate between different groupsof patients (with expected differencesin item/factor scores), e.g., patientswith clinician-determined adequatelyand inadequately controlledbreakthrough pain, patients with bonemetastases vs. no bone metastatses,patients with neuropathic pain, andpatients with poor performance status

Analysisdindependent T-tests.Construct validity:

Convergent validityThe purpose of these analyses was to

determine correlations between BATitem/summary scores and relatedmeasures, e.g., Brief Pain Inventoryitem scores, usage of rescuemedication

Analysisdcalculation of Pearsoncorrelation coefficients.

Correlation coefficient values of >0.1equate to a small correlation, of >0.3equate to a medium correlation, andof >0.5 equate to a strongcorrelation.19

Responsiveness The purpose of these analyses was todetermine whether the BAT can detectclinically significant changes inbreakthrough cancer pain.

Analysisdcalculation of effect size/Cohen’s coefficient

Cohen’s coefficient values of 0.2 equateto a small effect size, of 0.5 equate to amedium effect size, and of 0.8 equateto a large effect size.19

Acceptability The acceptability of the BAT wasdetermined by the completeness of thequestionnaire (i.e., amount of ‘‘missingdata’’)

<5% missing data was deemed to beacceptable.

BAT ¼ Breakthrough Pain Assessment Tool.

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ValidityThe mean scores for all BAT questions, with

the exception of duration of episode (‘‘Howlong does the typical breakthrough painepisode last?’’) were higher in the group with

patient-determined inadequately controlledbreakthrough pain compared with the groupwith patient-determined adequately controlledbreakthrough pain (Table 4). In contrast, onlythree BAT questions had significantly higher

Table 2Characteristics of Subjects Who Participated inthe Psychometric Testing of the Breakthrough

Pain Assessment Tool

CharacteristicsNumber of Patients

(N ¼ 100)

Age Median 61 y(range 27e89 yr)

GenderMale 54Female 46

Cancer diagnosisBreast 14Gastrointestinal 27Gynecological 4Hematological 7Head and neck 5Lung 16Urological 22Other 5

ECOG performance status0 31 272 343 234 13

Subject typeOutpatient 55Inpatient 45

Subject sourceHospital 80Hospice 20

Pain etiologyCancer-related 89Cancer treatment-related 8Mixed 2Unknown 1

Pathophysiology painNociceptive 72Neuropathic 2Mixed 26

ECOG ¼ Eastern Cooperative Oncology Group.

Table 3Factor Loading of Breakthrough Pain

Assessment Tool Items

Factor

1 2

How often do you get the breakthroughpain?

0.568

How long does a typical episode last? 0.801How severe is the worst breakthrough pain? 0.787How severe is a typical breakthrough pain? 0.800How much does the breakthrough paindistress you?

0.695

How much does the breakthrough painstop you from living a normal life?

0.787

How effective is the painkiller for yourbreakthrough pain?

0.531

How long does the breakthrough painkillertake to have a meaningful effect?

0.779

How much do the side effects from yourbreakthrough painkiller bother you?

0.468

1Eastern co-operative oncology group performancestatus relates to a patient’s general physical condi-tion (0 ¼ fully active, 1 ¼ restricted but ambulatoryand able to carry out light work, 2 ¼ ambulatory, un-able to carry out work, up and about more than 50%of time, 3 ¼ capable of limited self-care, confined tobed or chair for more than 50% of day,4 ¼ completely disabled, confined to bed or chair).

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scores in the group with clinician-determinedinadequately controlled breakthrough paincompared with the group with clinician-determined adequately controlled break-through pain (Table 4). These were the threequestions related to pain interference (‘‘Howmuch does the breakthrough pain stop youfrom living a normal life?) and analgesic effi-cacy (‘‘How effective is the painkiller for yourbreakthrough pain;’’ ‘‘How long does the pain-killer take to have a meaningful effect’’). Un-surprisingly, the results for patients whosemedication was changed following the clini-cian assessment were very similar to those forpatients with clinician-determined inade-quately controlled breakthrough pain.

BAT questions concerning breakthroughpain intensity were significantly higher in

patients with an Eastern Cooperative OncologyGroup performance status1 of 3e4 (P < 0.05),as were BAT interference questions (‘‘Howmuch does the breakthrough pain distressyou?,’’ ‘‘How does the breakthrough painstop you from living a normal life?’’). Neuro-pathic pain (assessed by clinical history and ex-amination) was associated with a significantlyhigher score in BAT item concerning break-through pain frequency (P ¼ 0.03) but notwith any of the other items. BAT questionscores were not significantly higher in patientswith metastatic disease or specifically in pa-tients with bone metastases.Correlations between BAT items and BPI

items are presented in Table 5. There was astrong correlation between the scores for‘‘How severe is a typical breakthrough pain?’’and the scores for ‘‘worst pain’’ on BPI (corre-lation coefficient/r ¼ 0.55). However, therewas an even stronger correlation between thescores for ‘‘How severe is your worst break-through pain?’’ and the scores for ‘‘worstpain’’ on BPI (r ¼ 0.89). In addition, therewas a medium correlation between the scoresfor ‘‘How effective is the painkiller that you

Table 4Comparisons of Breakthrough Pain Assessment Tool Summary Scores Between Groups Determined by Global

Impression of Breakthrough Pain Control

Patient’s Global Impression of BTCPClinician’s Global Impression of

BTCP

AdequatelyControlled(n ¼ 65)

InadequatelyControlled(n ¼ 34) P-value

AdequatelyControlled(n ¼ 28)

InadequatelyControlled(n ¼ 72) P-value

How often do you get breakthrough pain? 5.07 6.18 0.009 5.43 5.47 0.922How long does a typical episode of

breakthrough pain last?6.03 6.79 0.182 6.07 6.34 0.654

How severe is your worst breakthrough pain? 7.06 8.26 0.003 7.04 7.68 0.135How severe is a typical breakthrough pain? 5.51 6.39 0.019 5.62 5.86 0.544How much does the breakthrough pain

distress you?5.14 7.41 0.000 5.18 6.21 0.095

How much does the breakthrough pain stopyou from living a normal life?

5.47 7.36 0.002 4.89 6.66 0.005

How effective is the painkiller for yourbreakthrough pain (reversed)?

2.68 3.87 0.022 1.89 3.54 0.002

How long does the painkiller take to have ameaningful effect?

4.90 6.02 0.013 4.52 5.58 0.028

How much do the side effects from yourbreakthrough painkiller bother you?

2.10 4.40 0.002 1.81 3.21 0.076

BTCP ¼ breakthrough cancer pain.

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usually take for your breakthrough pain?’’ andthe scores for pain relief on BPI (r ¼ 0.48).

There also was a strong correlation betweenBAT scores for ‘‘How much does the break-through pain stop you from living a normallife?’’ and BPI scores for interference with gen-eral activity interference (r ¼ 0.67), mood(r ¼ 0.50), walking (r ¼ 0.62), and work(r¼ 0.57). In addition, there was a medium cor-relation between BAT scores for ‘‘How muchdoes the breakthrough pain stop you from livinga normal life?’’ and BPI scores for interferencewith relations with others (r ¼ 0.34) and enjoy-ment of life (r ¼ 0.48). However, there was littlecorrelation between BAT scores for ‘‘How muchdoes the breakthrough pain stop you from livinga normal life?’’ and BPI scores for interferencewith sleep (r ¼ �0.01) (Table 5).

There was a medium correlation betweenthe frequency of usage of rescue (‘‘break-through’’) medication and the items regardingbreakthrough pain frequency (r ¼ 0.387) andalso the typical pain intensity (r ¼ 0.384) andthe worst pain intensity (r ¼ 0.321)(Table 6). The correlation with breakthroughanalgesia was higher for all BAT items thanthe correlation with background analgesia.

The effect size for the BAT (Cohen’s coeffi-cient) was 0.87 based on a score summary. Thisis a large effect size according to standardcriteria. There were seven missing items in

the whole data set indicating acceptability ofBAT to cancer patients.

DiscussionThe aim of the project was to develop a clin-

ically useful breakthrough pain assessmenttool in cancer patients. Thus, the psychometrictesting of the BAT was undertaken in a diversegroup of cancer patients (i.e., diagnosis, per-formance status), and in a variety of care set-tings (i.e., hospital, hospice). The tool wasdeveloped with the assistance of patients withbreakthrough cancer pain, and the tool hadgood acceptability during the field-testing(minimal withdrawals, minimal missing data).

The original hypothesis was that the BATwould measure two to three underlying paindimensions based on analysis of generic cancerpain instruments. Item analysis revealed thatthe BAT did indeed conform to this hypothesisand items loaded onto two underlying dimen-sions or factors.

The first factor identified included ques-tions regarding breakthrough pain frequency,intensity (typical and worst), and break-through pain interference (‘‘How much doesthe breakthrough pain distress you?’’ and‘‘How much does breakthrough pain stopyou from living a normal life?’’). This factor

Table 5Convergent Validity Between Breakthrough Pain Assessment Tool and Brief Pain Inventory Pain Intensity Scores

BAT Items

Brief Pain Inventory Pain Intensity Items Brief Pain Inventory Interference Items

WorstPain

LeastPain

AveragePain

PainNow

TotalPain

SeverityScore

% Of PainRelief

GeneralActivity Mood Walking Work

RelationsWithOthers Sleep

EnjoymentOf Life Total

How often do you getbreakthrough pain?

0.344 0.201 0.354 0.216 0.295 �0.196 0.309 �0.008 0.012 0.165 0.216 0.316 0.262 0.239

How long does a typical episode ofbreakthrough pain last?

�0.052 0.066 0.088 0.142 0.089 �0.141 0.136 0.374 0.119 0.068 0.189 �0.199 0.105 0.167

How severe is your worstbreakthrough pain?

0.891 0.111 0.399 0.157 0.476 �0.065 0.346 0.266 0.233 0.210 0.127 0.396 0.448 0.427

How severe is a typicalbreakthrough pain?

0.545 0.213 0.473 0.431 0.559 �0.017 0.405 0.342 0.216 0.283 0.478 0.365 0.362 0.522

How much does the breakthroughpain distress you?

0.402 �0.185 0.320 0.011 0.151 0.104 0.126 0.3 0.355 0.342 0.253 0.175 0.362 0.396

How much does the BTCP stopyou from living a normal life?

0.366 �0.029 0.252 0.019 0.195 �0.110 0.672 0.5 0.615 0.571 0.336 �0.01 0.48 0.636

How effective is the painkiller foryour breakthrough pain?

0.028 0.172 �0.027 0.010 �0.009 0.483 0.211 �0.019 0.304 �0.073 �0.124 �0.049 0.079 0.051

How long does the painkiller foryour breakthrough pain take tohave a meaningful effect?

�0.151 0.051 �0.016 �0.037 �0.073 0.156 0.103 0.031 �0.167 0.003 �0.124 �0.08 �0.021 �0.075

How much do side effects fromyour BTCP painkiller botheryou?

�0.058 0.087 0.292 0.234 0.117 �0.024 0.012 0.245 �0.04 0.155 0.263 0.128 0.154 0.151

BAT ¼ Breakthrough Pain Assessment Tool; BTCP ¼ breakthrough cancer pain.All correlation coefficients have P-values <0.05. Correlation coefficient values of >0.1 represent a small correlation, >0.3 medium, >0.5 large.

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Table 6Convergent Validity Between the Breakthrough Pain Assessment Tool and Breakthrough and Background

Analgesia

Correlation WithFrequency of Taking

BreakthroughPainkillersa,b

Correlation WithBackground

Medication Dosage

How often do you get breakthrough pain? 0.387 �0.024How long does a typical episode of breakthrough pain last? 0.210 0.095How severe is your worst breakthrough pain? 0.321 0.136How severe is a typical breakthrough pain? 0.384 0.045How much does the breakthrough pain distress you? 0.146 0.093How much does the breakthrough pain stop you from living a normal life? 0.282 0.219How effective is the painkiller for your breakthrough pain (reversed)? 0.223 0.124How long does the painkiller take to have a meaningful effect? 0.182 0.017How much do the side effects from your breakthrough painkiller bother you? 0.213 0.137

aAll correlation coefficients have P-values <0.05.bCorrelation coefficient values of >0.1 represent a small correlation, >0.3 medium, >0.5 large.

Vol. - No. - - 2014 9Breakthrough Pain Assessment Tool (BAT)

also included the question ‘‘How much do theside effects from the painkiller for your break-through pain bother you?’’ An explanation forthis finding is that adverse effects are one ofthe most common reasons for not takingrescue medication for breakthrough pain(which undoubtedly has an influence on theimpact of the breakthrough pain).7 Indeed,analgesic side effects were of great importanceto patients in the interview stage of this study.16

Items about side effects are rarely included incancer pain assessment instruments, but theseresults demonstrate that this item is particu-larly relevant in the management of break-through pain.

It is interesting that BAT pain intensity itemscorrelated with BAT interference items. Thiscontrasts with the Brief Pain Inventory (BPI),where pain intensity and pain interferenceitems load onto two separate dimensions24e26

and undoubtedly this reflects the fact thatbreakthrough pain is a very different painexperience from background pain.

The second factor identified included thequestions ‘‘How long does a typical episodeof breakthrough pain last?’’ and ‘‘How effec-tive is the painkiller that you take for yourbreakthrough pain?’’ The pharmacodynamicprofile of the rescue medication is crucial tothe efficacy of the rescue medication, particu-larly as many breakthrough pain episodes areof short duration (and so require a rescuemedication with a rapid onset). Thus, it is un-surprising that these items loaded onto thesame underlying factor.

The BAT demonstrated acceptable test-retest reliability and internal consistency inthis group of patients: the coefficient for thetotal BAT score was above the recommendedcut-off.19 Thus, it is reasonable to concludethat BAT appears to be a reliable assessmenttool in this population of patients. The hightest-retest values reflect that patients arecorrectly following the instructions and ratingtheir breakthrough pain experience over theprevious week, as breakthrough episodes mayvary on a daily basis.

The BAT also demonstrated acceptableconstruct validity (i.e., hypothesis testing,convergent validity). As expected, BAT itemscores were significantly greater in patientswho deemed their breakthrough pain to beinadequately controlled, with the exceptionof the item assessing breakthrough painduration.

Most of the interference items on the BPIwere strongly correlated with the BAT item‘‘How much does the breakthrough pain stopyou from living a normal life?’’ This suggeststhat this question has validity in encompassingmultiple aspects of pain interference (withoutthe burden of asking multiple questions).However, the sleep interference item on theBPI was not correlated with the interferenceitem on the BAT. One explanation of thisresult is the existence of a circadian variationin the occurrence of breakthrough cancerpain. For example, Fine and Busch reportedthat 86% of patients experienced break-through pain during the day, whereas only

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45% of patients experienced breakthroughpain during the night.27 In addition, variousstudies have demonstrated a reduction in theuse of rescue (‘‘breakthrough’’) medicationduring the night/early morning.28,29

The results demonstrate that the BAT hasacceptable levels of convergent validity bycorrelating in an expected fashion withdifferent clinical and patient-related outcomevariables. The ability of the BAT to demon-strate clinically relevant changes over time isan important aspect of its applicability to clin-ical practice. The effect size of the total BATwas large, which indicated that patients’ break-through pain had improved over the course ofthe study. Breakthrough pain has been re-ported as an independent predictor for worsepain outcomes.30 However, this large effectsize, coupled with nearly 50% of patients re-porting an improvement in breakthroughpain after one consultation, emphasizes thepotential response of breakthrough pain tospecialist pain management.

There were a number of limitations to thisstudy. The main limitation is that the BATwas validated in an English-speaking popula-tion and in a single country (U. K.). Thus,further validation is required before the toolis introduced into other populations/coun-tries. Equally, further validation is requiredbefore the tool is introduced to patients withnonmalignant breakthrough pain.

Often studies that develop new measuresfield-test much longer prototypes, with thoseitems with the best psychometric properties be-ing retained (and vice versa). We undertook arigorous selection process for items to beincluded in the BAT. In defense of our meth-odology, the analysis revealed no redundantitems indicating that this approach to itemgeneration can produce psychometricallysound results. Moreover, the brevity of theBAT contributed to the acceptability of thetool and limited the attrition rate of the study.

Finally, a proportion of patients were unableto complete the follow-up assessments mainlyas the result of advanced disease. Palliativecare research has well-documented problemswith attrition because of the nature of the un-derlying illness.31 One of the objectives of thestudy was to be as inclusive as possible, and wedid not exclude patients on the basis that theymay not be able to complete follow-up. Thus, it

is important for patient-related outcome mea-sures to be valid for patients at all stages oftheir illness.

ConclusionThis study presents initial evidence for the

reliability and validity of the BAT, which canbe used as an outcome measure to quantifybreakthrough pain in cancer patients in a clin-ical setting. Additional studies are required tofurther assess the psychometric properties ofBAT and these are ongoing.

Disclosures and AcknowledgmentsThe study was funded by the Palliative Care

Research Funds at the Royal Surrey CountyHospital/Royal Marsden Hospital. The au-thors acknowledge the support of their chari-table donors (especially Joe Goodall and theother family and friends of Debora Matthews)and also of Cephalon Europe, which providedan unrestricted grant to support the comple-tion of this project. The authors declare noconflicts of interest.The authors thank the patients for taking

part in the study, the experts for supportingthe study, and their colleagues at the RoyalMarsden Hospital, St. Luke’s Cancer Centre,and St. Clare Hospice. In particular, the au-thors acknowledge the support provided byDr. Paul Farquhar-Smith (clinician involvedin assessing patients), Ms. Melanie Waghorn(research nurse), and Dr. Qamar Abbas (clini-cian involved in assessing patients).

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Appendix

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