Validity and responsiveness study using a randomized clinical trial and prospective cohort study of patients with low back pain (LBP).
To provide evidence for construct validity and responsiveness to change of a single-item presenteeism question (SIPQ) in patients with LBP.
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.
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.
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-specific 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.
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.
Level of Evidence: 2
Evidence of validity and responsiveness, a single-item presenteeism question (SIPQ), among patients with low back pain is lacking. This study provides convergent, divergent, discriminant validity, and responsiveness evidence of the SIPQ measuring presenteeism in a low back pain population. Further evidence is merited to assess its relationship with multi-item presenteeism questionnaires.
*Health Economics Unit, School of Health & Population Sciences, University of Birmingham, Birmingham, United Kingdom; and
†Arthritis Research UK Primary Care Centre, Primary Care Sciences, Keele University, Staffordshire, United Kingdom.
Address correspondence and reprint requests to Jesse Kigozi, MSc, Health Economics Unit, School of Health & Population Sciences, University of Birmingham, Birmingham, United Kingdom; E-mail: firstname.lastname@example.org; email@example.com
Acknowledgment date: August 30, 2013. First revision date: December 2, 2013. Acceptance date: December 8, 2013.
The manuscript submitted does not contain information about medical device(s)/drug(s).
The Arthritis Research UK Primary Care Centre (Doctoral Research Award in the area of economics of back pain) as part of work funded through Keele University funds were received by Jesse Kigozi.
No relevant financial activities outside the submitted work.