Carpal tunnel syndrome and manual work: a longitudinal study.

OBJECTIVE: To assess risks associated with work-related biomechanical overloads in onset/course of carpal tunnel syndrome.

METHODS: Work-groups with job tasks spanning different biomechanical exposures were evaluated at baseline in terms of American Conference of Governmental Industrial Hygienists hand-activity/peak force action limit and threshold limit values (TLV). Exposures of interest were "unacceptable" (hand-activity above TLV) and "borderline" (between action limit and TLV) overloads. Clinical/individual data were collected at baseline and 12 months.

RESULTS: One-year incidence of "classic/possible" carpal tunnel syndrome symptoms as defined by consensus criteria was 7.3% (153 of 2092). "Unacceptable" overload was associated with a 3-fold increased risk of onset with respect to "acceptable" load. At ordered logistic regression analysis of symptom-status variations, increased risks were recorded for "unacceptable" and "borderline" overloads.

CONCLUSIONS: Effectiveness of encouraging workplace adherence to the American Conference of Governmental Industrial Hygienists recommendations deserves investigation as a possible key to wide-scale prevention.