Clinimetric Properties of Self-reported Disability Scales for Whiplash

Abstract

Objectives: A core outcomes set (COS) for whiplash-associated disorders (WADs) has been proposed to improve consistency of outcome reporting in clinical trials. Patient-reported disability was one outcome of interest within this COS. The aim of this review was to identify the most suitable tools for measuring self-reported disability in WAD based on clinimetric performance.Methods: Database searches took place in 2 stages. The first identified outcome measures used to assess self-reported disability in WAD, and the second identified studies assessing the clinimetric properties of these outcome measures in WAD. Data on the study, population and outcome measure characteristics were extracted, along with clinimetric data. Quality and clinimetric performance were assessed in accordance with the Consensus-based Standards for the Selection of Health Status Measurement Instruments (COSMIN).Results: Of 19,663 records identified in stage 1 searches, 32 were retained following stage 2 searches and screening. Both the Whiplash Disability Questionnaire and Neck Disability Index performed well in reliability (intraclass correlation coefficient = 0.84 to 0.98), construct validity (74% to 82% of hypotheses accepted), and responsiveness (majority of correlations in accordance with hypotheses). Both received Category B recommendations due to a lack of evidence for content validity.Discussion: This review identified the Neck Disability Index and Whiplash Disability Questionnaire as the most appropriate patientreported outcome measures (PROMs) for assessing self-reported disability in WAD based on moderate to high-quality evidence for sufficient reliability, construct validity and responsiveness. However, the content validity of these PROMs has yet to be established in WAD, and until this is undertaken, it is not possible to recommend 1 PROM over the other for inclusion in the WAD COS.

Recommendations for a core outcome measurement set for clinical trials in whiplash associated disorders

“…Content validity of the NDI has been examined in people with nontraumatic neck pain and found to be poor, 1 although these findings may not necessarily extrapolate to WAD. 14 Moderate- to high-quality evidence for sufficient psychometric performance of both the NDI and WDQ with respect to structural validity, internal consistency, reliability (ICC 0.84-0.98), construct validity (74%-82% of hypotheses accepted), and responsiveness (majority of correlations in accordance with hypotheses) was found. 14 Because of the very low–quality evidence for the content validity of both instruments, the strength of recommendations was downgraded from level A to level B, meaning that further evaluation of both is necessary, and it was concluded that neither could be recommended over the other.…”

“…The results of the systematic reviews of core measurement instruments for Physical Functioning, Perceived Recovery, Psychological Functioning, and Pain have been published elsewhere. 4,14,20,28…”

“…26 COSMIN have identified 9 measurement properties relevant for PROMs: content validity, structural validity, internal consistency, cross-cultural validity, reliability, measurement error, criterion validity, construct validity, and responsiveness. 26 Four systematic reviews (Physical Functioning, Psychological Functioning, Quality of Life, and Pain domains) were conducted to evaluate the psychometric properties of identified instruments in patients with WAD (Griffin et al 14 Ritchie et al 28 Ravn et al unpublished data, Modaressi et al 20 ). For the domain of Perceived Recovery, the results of a recent systematic review of outcome instruments in people with neck pain, but not specifically WAD, and conducted by members of the International Steering Committee were used.…”

“…Forty-three PROMs were identified for Physical Functioning, 14 2 for Perceived Recovery, 4 37 for Psychological Functioning, 28 17 for Quality of Life, and 2 for Pain Intensity 20 (Appendix 1, available as supplemental digital content at http://links.lww.com/PAIN/ B819). For Work Functioning, numerous single-item measures were identified.…”

“…Of these, 3 PROMS, the Neck Disability Index (NDI), the Whiplash Disability Questionnaire (WDQ), and the Whiplash Activity and Participation List (WAL) had been examined for their performance across at least 7 psychometric properties and were therefore eligible to undergo the modified GRADE assessment outlined by COSMIN. 14 Evidence for performance of the WAL was from one low-quality study, and as such, it was not further considered. 14 The development of both the NDI and WDQ was rated as inadequate quality because no cognitive interviews were performed.…”