Text

Introduction: We previously found that one-year occupational mechanical hand exposure increases the risk of carpal tunnel syndrome (CTS). However, only a few studies have investigated the effects of cumulative exposure. This study aimed to examine the association between three-years of cumulative occupational mechanical hand exposure and the risk of CTS, with a focus on identifying exposure-response relationships.

Methods: This nationwide cohort study included 1,147,597 women and 1,189,205 men born in Denmark between 1945 and 1994 identified through national registers. During the follow-up (2010–2013), 12,343 patients with CTS were identified. Occupational mechanical exposures (i.e., forceful movements, repetitive movements, non-neutral postures, hand-arm vibrations, and combined hand exposures (hand load)) were assessed by linking DISCO-08 job codes with a hand-specific job exposure matrix. Associations were estimated using multivariate logistic regression. Both surgically and non-surgically treated CTS cases were analyzed.

Results: The overall incidence rate was nearly twice as high in women than in men. For both sexes, clear exposure-response relationships were observed for all occupational mechanical exposures. Among women, the highest adjusted odds ratios (ORsadj) were found in those exposed to the highest category of non-neutral hand postures and combined hand load; ORadj 2.6 (95% CI 2.4-2.9) and 3.0 (95% CI 2.6-3.4), respectively. Among men, the highest ORsadj were found for forceful movements, with an OR of 3.4 (95% CI 3.0-3.7) and combined hand load, with an ORadj of 3.2 (95% CI 2.8-3.7). ORsadj was generally higher in surgically treated cases than in nonsurgical cases.

Discussion: Our results corroborate those of previous research by reinforcing the role of occupational mechanical hand exposure as a risk factor for CTS. Importantly, the findings emphasize that assessing exposure limited to the year immediately preceding the diagnosis may be inadequate. A more comprehensive understanding of CTS etiology requires consideration of cumulative hand exposure up to three-year before diagnosis.

Conclusion: Over a three-year period, cumulative occupational mechanical hand exposure was significantly associated with an elevated risk of CTS, particularly among males and those undergoing surgical intervention.

References