Beyond return to work: testing a measure of at-work disability in workers with musculoskeletal pain

BACKGROUND: There are a limited number of validated measures of a patient's perception of the level of difficulty that they are having at their job. The purpose of this study was to evaluate the psychometric properties of the 16-item Work Limitations Questionnaire (WLQ-16). METHODS: A sample of 42 workers reporting to a workplace occupational health unit with upper limb or low back pain were enrolled in an observational study. Participants were assessed at baseline, 4 and 12 weeks post reporting. Psychometric testing (distributions, Cronbach's alpha, construct validity and responsiveness to change in problem and pain) was done using the baseline and 12-week data. RESULTS: The WLQ-16 had evidence of internal consistency, construct validity and responsiveness. Some ceiling effect was found in the domains of mental-interpersonal and output demands. Physical demands suffered from missing values in 18/42 due to not-applicable content. Construct validity revealed that there was less discrimination at the higher (less limited) end of the scale. Responsiveness was present, though less than found with other measures of function and pain. CONCLUSIONS: The WLQ-16 shows promise as a measure of at-work disability. Further testing to evaluate the ceiling effect and responsiveness to constructs of change more closely related to work disability is recommended