Construct Validity and Responsiveness of the Single-Item Presenteeism Question in Patients With Lower Back Pain for the Measurement of Presenteeism

Study Design. Validity and responsiveness study using a randomized clinical trial and prospective cohort study of patients with low back pain (LBP). Objective. To provide evidence for construct validity and responsiveness to change of a single-item presenteeism question (SIPQ) in patients with LBP. Summary of Background Data. The SIPQ is a simple, easy to administer tool that has been used to measure the impact of back pain on reduced productivity at work (presenteeism) as a standalone measure. Evidence supporting the validity and responsiveness of the SIPQ among patients with back pain is however lacking. Methods. The SIPQ was administered to patients consulting for back pain in a randomized controlled trial (N = 851) and a cohort intervention study (N = 922). Construct validity was assessed using convergent, divergent, and known-group validity. The validity investigation included assessing associations between the SIPQ and pain, disability, psychological, health status, and quality of life measures. Responsiveness was assessed using external indicators of change as comparators, evaluating correlation of clinical change scores and effect size statistics. Results. Moderate to strong correlations were found between presenteeism and pain (r: 0.44-0.77), disability (r: 0.53-0.70), and 12-Item Short Form Health Survey physical dimensions (r: -0.66 to -0.55). Presenteeism was strongly associated with disease-specifi c pain and disability scales. The SIPQ was responsive to changes in productivity-presenteeism change scores indicated strong correlation with change scores, and high responsiveness in distribution-and anchor-based testing. Conclusion. The SIPQ is a potentially valid and responsive tool for assessing the impact of back pain on presenteeism. This SIPQ could, with relative ease, facilitate further research on the estimation of presenteeism within economic evaluation studies of musculoskeletal conditions, thus providing policymakers with estimates of economic impact of musculoskeletal disease. Further evidence is, however, merited to assess its relationship with standardized presenteeism questionnaires.