PT  - JOURNAL ARTICLE
AU  - Carisa Harris-Adamson
AU  - Ellen A Eisen
AU  - Andreas Neophytou
AU  - Jay Kapellusch
AU  - Arun Garg
AU  - Kurt T Hegmann
AU  - Matthew S Thiese
AU  - Ann Marie Dale
AU  - Bradley Evanoff
AU  - Stephen Bao
AU  - Barbara Silverstein
AU  - Fred Gerr
AU  - Susan Burt
AU  - David Rempel
TI  - Biomechanical and psychosocial exposures are independent risk factors for carpal tunnel syndrome: assessment of confounding using causal diagrams
AID  - 10.1136/oemed-2016-103634
DP  - 2016 Nov 01
TA  - Occupational and Environmental Medicine
PG  - 727--734
VI  - 73
IP  - 11
4099  - http://oem.bmj.com/content/73/11/727.short
4100  - http://oem.bmj.com/content/73/11/727.full
SO  - Occup Environ Med2016 Nov 01; 73
AB  - Background Between 2001 and 2010, six research groups conducted coordinated prospective studies of carpal tunnel syndrome (CTS) incidence among US workers from various industries to estimate exposure–response relationships.Objective This analysis examined the presence and magnitude of confounding between biomechanical and workplace psychosocial factors and incidence of dominant-hand CTS.Methods 1605 participants, without CTS at enrolment, were followed for up to 3.5 years (2471 person-years). Demographic information, medical history and workplace psychosocial stress measures were collected at baseline. Individual workplace biomechanical exposures were collected for each task and combined across the workweek using time-weighted averaging (TWA). CTS case criteria were based on symptoms and results of electrophysiological testing. HRs were estimated with Cox proportional hazard models. Confounding was assessed using causal diagrams and an empirical criterion of 10% or greater change in effect estimate magnitude.Results There were 109 incident CTS cases (IR=4.41/100 person-years; 6.7% cumulative incidence). The relationships between CTS and forceful repetition rate, % time forceful hand exertion and the Threshold Limit Value for Hand Activity Level (TLV-HAL) were slightly confounded by decision latitude with effect estimates being attenuated towards the null (10–14% change) after adjustment. The risk of CTS among participants reporting high job strain was attenuated towards the null by 14% after adjusting for the HAL Scale or the % time forceful hand exertions.Conclusions Although attenuation of the relationships between CTS and some biomechanical and work psychosocial exposures was observed after adjusting for confounding, the magnitudes were small and confirmed biomechanical and work psychosocial exposures as independent risk factors for incident CTS.