Objectives To quantify the relationship between workplace physical factors, particularly hand activity level (HAL) and forceful exertion and carpal tunnel syndrome (CTS), while taking into account individual factors. To compare quantitative exposure assessment measures with more practical ratings-based measures.
Methods In a group of healthcare and manufacturing workers, each study participant's job tasks were evaluated for HAL, forceful exertion and other physical stressors and videotaped for further analysis, including frequency and duration of exertion and postural deviation. Electrodiagnostic testing of median and ulnar nerves and questionnaires were administered to all participants. A CTS case required median mononeuropathy and symptoms on hand diagrams in fingers 1–3. Multiple logistic regression models were used to analyse associations between job and individual factors and CTS.
Results Of 477 workers studied, 57 (11.9%) were dominant hand CTS cases. Peak force ≥70% maximum voluntary contraction versus <20% maximum voluntary contraction resulted in an OR of 2.74 (1.32–5.68) for CTS. Among those with a body mass index ≥30, the OR for ≥15 exertions per minute was 3.35 (1.14–9.87). Peak worker ratings of perceived exertion increased the odds for CTS by 1.14 (1.01–1.29) for each unit increase on the 10-point scale. The odds for CTS increased by 1.38 (1.05–1.81) for each unit increase on the HAL 10-point scale among men, but not women. Combined force and HAL values above the ACGIH TLV for HAL resulted in an OR of 2.96 (1.51–5.80) for CTS.
Discussion/Conclusions Quantitative and ratings-based job exposure measures were each associated with CTS. Obesity increased the association between frequency of exertion and CTS.
- Upper limb musculoskeletal disorders
- exposure assessment methods
- body mass index
- occupational health practice
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Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.
This work was written by officers or employees of the US government as part of their official duties, and therefore, it is not subject to US copyright.
Funding This study was funded by the Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, as part of the National Occupational Research Agenda (NORA I) research program in 2000.
Competing interests None.
Patient consent Obtained.
Ethics approval This study was conducted with the approval of the NIOSH Human Subjects Review Board.
Provenance and peer review Not commissioned; externally peer reviewed.
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