Carpal tunnel syndrome and occupational hand exposures: a Danish nationwide cohort study.

Objectives: The aim was to examine exposure-response relations between occupational hand exposures and carpal tunnel syndrome (CTS) and to compare the relation between surgery-treated and non-surgery-treated CTS. The secondary aim was to study sex-specific differences in exposure-response relations.

Methods: We conducted a nationwide register-based cohort study of all persons born in Denmark (1945-1994). During follow-up (2010-2013), we identified first-time events of CTS. Occupational hand exposure estimates the year before each follow-up year were obtained by linking individual occupational codes with a job exposure matrix. We used multivariable logistic regression equivalent to discrete survival analysis based on sex and surgery. The excess fraction of cases was calculated.

Results: For both sexes, exposure-response relations were found for all occupational hand exposures. Among men, we found OR_adj of 3.6 (95% CI 3.2 to 3.8) for hand-related force, 2.9 (95% CI 2.5 to 3.2) for repetitive hand movements, 3.8 (95% CI 2.7 to 5.2) for non-neutral hand posture and 2.5 (95% CI 2.2 to 2.7) for hand-arm vibration in the highest exposure groups. For combined exposure (hand load), OR_adj was 3.5 (95% CI 3.1 to 4.0). Slightly higher ORs_adj were generally found for surgery-treated CTS compared with non-surgery-treated CTS for both sexes. When comparing sex, somewhat higher ORs_adj were found among men. The excess fraction was 42%.

Conclusions: Occupational hand exposures carried a 3-5-fold increased risk of CTS with slightly higher risks for surgery-treated compared with non-surgery-treated CTS. Even though CTS occurs more frequently among women, somewhat higher exposure-response relations were found for men compared with women. In the general working population, a substantial fraction of first-time CTS could be related to occupational hand exposures.