A New Instrument for Assessing Work-Related Body Mechanics and Strain in the General Population.

Clinical pain is often linked to poor body mechanics, with individuals sometimes presenting multiple painful disorders. Such disorders may be influenced by behaviors that affect the general resiliency and health of the musculoskeletal system. We aimed to develop a self-reported scale using the Malmö Diet and Cancer Study questions on work-related body mechanical exposures. An expert panel identified 41 variables having content validity for musculoskeletal problems. Exploratory factor analysis was conducted on a random selection of 50% of the cohort (n = 6,789 adults); the remaining was reserved for confirmatory factor analyses (CFA), item response theory (IRT) item calibration, and differential item functioning investigations. Supported by standard measure development methods and fit criteria, the final unidimensional item bank contains 13 items. Overall CFA statistics (root mean square error of approximation = .09; comparative fit index = .96; Tucker-Lewis index = .96; standardized root mean residuals = .05) indicated excellent single-factor model fit and appropriateness of IRT modeling and calibration. Expert review and item information values (score-precision) guided selection of an 8-item short form with acceptable score-level reliabilities (≥.70) for T-scores = 39-80+. This measure provides reliable assessment of body mechanics strain in adults and can be useful when evaluating different contributions to musculoskeletal problems affecting pain-treatment success in future clinical research. PERSPECTIVE: This article presents the development and psychometric properties of a new measure, "Work-related Body Mechanics and Strain Scale (WR-BMSS)." The scale has 13-items or alternatively an 8-item short form. This measure could potentially help clinicians who seek to assess how musculoskeletal problems may contribute to patient pain and disability.