ABSTRACT
Background Between 2001 and 2010, five research
groups conducted coordinated prospective studies of
carpal tunnel syndrome (CTS) incidence among US
workers from various industries and collected detailed
subject-level exposure information with follow-up of
symptoms, electrophysiological measures and job
changes.
Objective This analysis examined the associations
between workplace biomechanical factors and incidence
of dominant-hand CTS, adjusting for personal risk
factors.
Methods 2474 participants, without CTS or possible
polyneuropathy at enrolment, were followed up to
6.5 years (5102 person-years). Individual workplace
exposure measures of the dominant hand were collected
for each task and included force, repetition, duty cycle
and posture. Task exposures were combined across the
workweek using time-weighted averaging to estimate
job-level exposures. CTS case-criteria were based on
symptoms and results of electrophysiological testing. HRs
were estimated using Cox proportional hazard models.
Results After adjustment for covariates, analyst
(HR=2.17; 95% CI 1.38 to 3.43) and worker (HR=2.08;
95% CI 1.31 to 3.39) estimated peak hand force,
forceful repetition rate (HR=1.84; 95% CI 1.19 to 2.86)
and per cent time spent (eg, duty cycle) in forceful hand
exertions (HR=2.05; 95% CI 1.34 to 3.15) were
associated with increased risk of incident CTS.
Associations were not observed between total hand
repetition rate, per cent duration of all hand exertions,
or wrist posture and incident CTS.
Conclusions In this prospective multicentre study of
production and service workers, measures of exposure to
forceful hand exertion were associated with incident CTS
after controlling for important covariates. These findings
may influence the design of workplace safety
programmes for preventing work-related CTS.