¹Washington University School of Medicine, St. Louis, United States
²University of Angers, Angers, France
³INSERM (L'Institut national de la santé et de la recherche médicale ), Paris, France

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Introduction: Most studies of Carpal Tunnel Syndrome have examined only current workplace exposures as risk factors. We examined the effects of both recent and past work exposures on the incidence of surgery for carpal tunnel release (CTR).

Methods: Participants in a large prospective French general population study (CONSTANCES) were surveyed between 2012 and 2017. The survey included self-reported history of current and past jobs, allowing estimation of past and current workplace physical exposures using an existing job exposure matrix (ConstancesJEM). The ConstancesJEM was created by pooling self-reported work exposures at the level of the job title, and applying the mean exposure to all workers in the same job. CTR cases were ascertained through matching the surveys to national health insurance data for the 8-year period 2009-2016. Analyses were restricted to workers with some period of full-time work in 1999 or later. Poisson regression analyses (controlling for age, Body Mass Index (BMI), and sex) computed the relative risks (RR) of future CTR associated with different work exposures. Eleven exposures including physical force, repetition, posture, and keyboard use were categorized into quartiles, with the top quartile referenced on lower quartiles. Exposures were assigned during each active working year, and accounted for job changes. Models included different time periods of exposure and/or different exposure lag times.

Results: 777 cases of CTR were observed among the 56,289 person cohort. Those with CTR were more likely to be female, older, and to have a higher BMI. In both men and women, each of the 11 exposures was significantly associated with the incidence of CTR. In the cohort as a whole, RR of CTR per 5 years of exposure in the upper quartile included 1.19[1.13-1.25] for pressing with the base of the hand, 1.17[1.12-1.23] for use of vibrating tools, 1.17 [1.12-1.22] for rotation of the forearm, and 0.88[0.84-0.91] for keyboard use. Women showed larger effect sizes than men for some exposures, including repetition, use of vibrating tools, and pressing with the base of the hand. Higher effect sizes were seen among current workers than among those who had not worked in 5 or more years. Lagging exposures by 3 and 5 years reduced the strengths of association.

Discussion: Use of a JEM in a large general population cohort allowed us to study the effects of both recent and past work exposures on the incidence of carpal tunnel syndrome. While more recent exposures had stronger associations with CTR, some past exposures were also associated with future risk of CTR.