The impact of neglecting analgesics in musculoskeletal pain research: a modeling study using nationally representative panel data

Objective: Analgesics use is rarely considered in studies of work exposures and musculoskeletal pain. We examined weather ignoring analgesics biases estimated associations. Methods: Using a three-wave panel data (n=5139), we assessed whether the link between forward bending at work and reported back pain reflect the initial pain response before analgesic use. Results: Analgesic use influenced estimates. Bias depended on pain relief magnitude, prevalence of use, and analysis method. All methods generally underestimated association. Unadjusted analyses were most sensitive to pain relief magnitude, with greater bias at higher relief. Bias was larger in populations with higher analgesic use. Patterns were consistent across sample size (n=200, 1000, 5139). Conclusions: Ignoring analgesics may bias studies of pain outcomes and should be considered in design, analysis, and interpretation.