Carpal tunnel syndrome in repetitive work: A follow-up study

Background The Project on Research and Intervention in Monotonous work (PRIM) studied Danish workers for 3-4years to determine the effects of monotonous work. The present study is a subset of that cohort and compares prevalence and incidence differences of carpal tunnel syndrome (CTS) between workers with highly repetitive work tasks and workers with varied work tasks. Methods The baseline study included 731 participants. Follow-up examinations were performed after 6 and 18 months. The CTS diagnosis was based on symptom interviews and nerve conduction tests. The repetitiveness levels were determined with electrogoniometers and observation of cycle times. Results The overall prevalence of CTS was 1.6% on the working hand and 0.7% on the other hand. There was a significantly increased risk of CTS for every 10-hr increase of repetitive non-forceful work (OR = 1.84; 95% CI = 1.06-3.19) on the working hand. This result, however, was based on few cases and a low prevalence in the control group. The overall annual CTS incidence was 0.62% on the working hand and 0.44% on the other hand. For the repetitive work tasks, the mean power frequencies ranged from 0.53 to 0.79 Hz. Conclusions In the baseline study, highly repetitive work was associated with CTS. The CTS incidence was too low to perform any analyses of exposure differences. (Less)