Physical work load factors and carpal tunnel syndrome: a population-based study

Objective: Carpal tunnel syndrome (CTS) is the most common nerve entrapment syndrome. Studies on selected occupational populations suggest an association of CTS with forceful repetitive work and vibration. Only few population-based studies have addressed the role of physical load factors in CTS. The aim of this study was to investigate the relations between exposures to a single or a combination of physical work load factors and CTS. Methods: The target population consisted of people aged 30 years or older residing in Finland during 2000-2001. Of the 7977 eligible subjects, 6254 (78.4%) were included in the study. Occupational physical load factors were assessed by interview and CTS by physical examination. Results: The prevalence of possible or probable CTS was 2.1% in men and 5.3% in women. Work tasks with vibrating tools (adjusted odds ratio (OR) 1.9, 95% CI 1.2 to 2.9) and handgrip with high forces (OR 1.7, 95% CI 1.2 to 2.5) were related to an increased prevalence of CTS. There were joint effects between work tasks requiring handgrip with high forces and the use of vibrating tools (adjusted OR 3.3, 95% CI 2.0 to 5.4), between forceful activities (handgrip with high forces or handling of loads) and repetitive movements of the hands (OR 2.1, 95% CI 1.5 to 2.9), and between repetitive movements of the hands and the use of vibrating tools (OR 2.8, 95% CI 1.6 to 4.8). Only exposure in the most recent job was associated with CTS. Conclusions: Work tasks demanding handgrip with high forces or the use of vibrating tools are associated with CTS. The association is stronger if these work tasks are accompanied by repetitive movements of the hand or wrist.