Comparisons of measures for quantifying repetition in predicting carpal tunnel syndrome

Abstract Carpal tunnel syndrome (CTS) is the most commonly reported work-related musculoskeletal disorder of the upper extremity. While a causal relationship has been found between the repetitiveness of job tasks and CTS development, no studies have compared the predictive accuracy of various measures used to quantify repetition. The objective of this study was to compare the accuracy of measures commonly used to quantify repetition (cycle time (CT), number of hand movements (HM), and exposure classification (EC)) (i.e. high and low repetition), in predicting CTS and positive findings for CTS. Participant exposure to repetition was quantified through direct and video observation of operators within a fish processing facility. Logistic regression results indicate that for diagnosed CTS, HM were the only repetition measure to have a significant relationship, and was tentatively concluded to be the best predictor. Three interactions were also found to have significant relationships with diagnosed CTS (HM×Age, HM×Gender×Age, EC×Gender×Age). No statistically significant results were found for positive findings for CTS. The accuracy measures (percent correct, sensitivity, specificity, false positive, and false negative) did not differ for each repetition measure or interactions with the covariates considered for either dependent variable. Relevance to industry This research provides guidance on accurate assessment of exposure to repetition for prioritizing job tasks relative to risk of developing carpal tunnel syndrome.