Abstract
Background The Work Limitations Questionnaire-25 (WLQ-25) and the Work Instability Scale for Rheumatoid Arthritis (RA-WIS) have been used to measure at-work disability related to musculoskeletal disorders. However, a recent systematic review has shown that important psychometric properties still needed to be evaluated.
Objective The purpose of this study was to establish the validity and responsiveness of the WLQ-25 and RA-WIS in people with chronic work-related upper-extremity disorders.
Design Two-hundred six participants with chronic upper-extremity disorders who attended a specialty clinic operated by the Workplace Safety & Insurance Board of Ontario were evaluated at their initial visit and 6 months later.
Methods Questionnaires completed at each evaluation were: the WLQ-25, the RA-WIS, the QuickDASH, the pain subscale of the Shoulder Pain and Disability Questionnaire, and the Chronic Pain Grade Questionnaire. At the 6-month evaluation, participants completed a global rating of change question. Known-group and construct convergent validity were assessed using analysis of variance and Pearson correlations, and standardized response means (SRMs) were used to assess responsiveness. Clinically important differences (CIDs) also were determined.
Results The WLQ-25 and RA-WIS had low to moderate correlations with pain and disability scales (.28<r<.62) and discriminated among different functional categories (P<.001). For improved participants, the WLQ-25 (SRM=0.65 for summed score, SRM=0.63 for index score) and the RA-WIS (SRM=0.66) demonstrated moderate responsiveness. The CID for improvement was estimated to be 13/100 points for the WLQ-25 summed score, 5/28.6 points for the WLQ-25 index score, and 4/23 points for the RA-WIS.
Limitations The external criterion of change was specific to change in upper-extremity condition and not to change in work ability or productivity.
Conclusions The WLQ-25 and RA-WIS provide different information from that provided by pain and disability measures. They discriminate among functional outcome subgroups and detect improvement over time in people with chronic work-related upper-extremity disorders.
Footnotes
Dr Roy, Dr MacDermid, Dr Amick, Dr Shannon, Dr McMurtry, Dr Roth, Mr Tang, and Dr Beaton provided concept/idea/research design. Dr Roy, Dr MacDermid, Dr Amick, Dr McMurtry, Dr Grewal, and Dr Beaton provided writing. Dr MacDermid and Dr Beaton provided data collection and fund procurement. Dr Roy, Dr Amick, Dr Shannon, Mr Tang, and Dr Beaton provided data analysis. Dr Roy, Dr MacDermid, and Dr Beaton provided project management. Dr MacDermid, Dr McMurtry, Dr Roth, and Dr Beaton provided participants. Dr MacDermid and Dr Roth provided institutional liaisons. Dr MacDermid provided clerical support. Dr MacDermid, Dr Amick, Dr Shannon, Dr McMurtry, Dr Roth, Dr Grewal, and Mr Tang provided consultation (including review of manuscript before submission).
The authors acknowledge the collaboration of the staff and injured workers from the 2 WSIB specialty clinics involved in this study: the Holland Orthopaedic and Arthritis Centre Shoulder and Elbow Specialty Clinic, Toronto, Ontario, Canada, and St Joseph's Health Centre Upper Extremity Specialty Clinic, London, Ontario, Canada. The authors also acknowledge the contribution of the other investigators involved in the larger study design and implementation: Pierre Cote, Renee-Louise Franche, Sheilah Hogg-Johnson, Sonia Pagura, Robin Richards, and Claire Bombardier. Special thanks to Diana Sayers, Muge Dogan, Taucha Inrig, and Iona MacRitchie for assistance with implementing the study.
This study was approved by the institutional review boards of the University of Western Ontario, St Michael's Hospital, Sunnybrook Health Sciences Centre, and the University of Toronto.
During the conduct of this study, Dr Roy was supported by scholarships from the Fonds de la Recherche en Santé du Québec (FRSQ) and the Canadian Institutes of Health Research (CIHR), and Dr MacDermid and Dr Beaton were supported by a CIHR New Investigators award. Mr Tang is supported by a CIHR PhD fellowship, a Canadian Arthritis Network/Arthritis Society Trainee Fellowship, and a Syme Fellowship from the Institute for Work & Health.
- Received August 21, 2009.
- Accepted October 7, 2010.
