Neck and shoulder symptoms and disorders among Danish computer workers.

OBJECTIVES Neck and shoulder pain and disorders were studied among frequent computer users, and the associated effect of mouse and keyboard use was evaluated. METHODS Technical assistants and machine technicians were followed for 1 year. Questionnaires were sent to 9480 persons (initial response 73%, follow-up response 82%). Computer use information was obtained from the questionnaires. Symptom cases at baseline and follow-up were clinically examined using a standardized clinical protocol. The main outcomes were self-reported pain symptoms in the neck and right shoulder and clinical cases of rotator cuff syndrome, tension neck syndrome, and neck-shoulder pain with pressure tenderness. RESULTS The prevalence of moderate-to-severe pain in the neck and right shoulder was 4.1% and 3.4%, respectively, and the 1-year incidence for no or minor baseline symptoms was 1.5% and 1.9%, respectively. At baseline, the prevalence rate ratio (PRR) for neck pain was 1.7 [95% confidence interval (95% CI) 1.1-2.6] for mouse use >25 hours/week, that for right shoulder pain increased from 1.6 (95% CI 1.1-2.4) for 15-19 hours/ week to 2.5 (95% CI 1.4-4.3) for >30 hours/week of mouse use, and that for tension neck syndrome increased from 3.5 (95% CI 1.0-12) for 25-29 hours/week to 4.7 (95% CI 1.2-18) for >30 hours/week of mouse use. The relative risk (RR) for new neck pain was 1.8 (95% CI 0.8-3.9) for keyboard use > or = 15 hours/week and increased to 2.4 (95% CI 0.8-6.8) for > or = 30 hours/week. New right-shoulder pain symptoms were associated with mouse use >20 hours/week (RR 1.9, 95% Cl 1.0-3.5, and RR 3.3, 95% CI 1.2-8.9) and with keyboard use >15 hours/week (RR 2.2, 95% CI 1.0-4.9). CONCLUSIONS Mouse use is associated with an increased risk of moderate-to-severe pain in the neck and right shoulder, and an association with tension neck syndrome is possible.