title: Biomechanical risk factors for carpal tunnel syndrome: a pooled study of 2474 workers.
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.
authors.affiliation: Department of Environmental Health Sciences, University of California Berkeley, Berkeley, California, USA Department of Physical Therapy, Samuel Merritt University, Oakland, California, USA.
authors.forename: Carisa
authors.initials: C
authors.lastname: Harris-Adamson
authors.affiliation: Department of Environmental Health Sciences, University of California Berkeley, Berkeley, California, USA.
authors.forename: Ellen A
authors.initials: EA
authors.lastname: Eisen
authors.affiliation: Center for Ergonomics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Kapellusch
authors.affiliation: Center for Ergonomics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA.
authors.forename: Arun
authors.initials: A
authors.lastname: Garg
authors.affiliation: Rocky Mountain Center for Occupational and Environmental Health (RMCOEH), University of Utah, Salt Lake City, Utah, USA.
authors.forename: Kurt T
authors.initials: KT
authors.lastname: Hegmann
authors.affiliation: Rocky Mountain Center for Occupational and Environmental Health (RMCOEH), University of Utah, Salt Lake City, Utah, USA.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Thiese
authors.affiliation: Division of General Medical Science, Washington University School of Medicine, Saint Louis, Missouri, USA.
authors.forename: Ann Marie
authors.initials: AM
authors.lastname: Dale
authors.affiliation: Division of General Medical Science, Washington University School of Medicine, Saint Louis, Missouri, USA.
authors.forename: Bradley
authors.initials: B
authors.lastname: Evanoff
authors.affiliation: Previously with the National Institute for Occupational Safety and Health (NIOSH), Cincinnati, Ohio, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Burt
authors.affiliation: Safety and Health Assessment and Research for Prevention (SHARP) Program, Washington State Department of Labor and Industries, Olympia, Washington, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Bao
authors.affiliation: Safety and Health Assessment and Research for Prevention (SHARP) Program, Washington State Department of Labor and Industries, Olympia, Washington, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Silverstein
authors.affiliation: Department of Occupational and Environmental Health, University of Iowa, College of Public Health, Iowa City, Iowa, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Merlino
authors.affiliation: Department of Occupational and Environmental Health, University of Iowa, College of Public Health, Iowa City, Iowa, USA.
authors.forename: Fred
authors.initials: F
authors.lastname: Gerr
authors.affiliation: Division of Occupational and Environmental Medicine, University of California at San Francisco, San Francisco, California, USA Department of Bioengineering, University of California Berkeley, Berkeley, California, USA.
authors.forename: David
authors.initials: D
authors.lastname: Rempel
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002349:Carpal Tunnel Syndrome / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D015994:Incidence; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D014459:Ulnar Nerve / Q000503:physiopathology; D014481:United States / Q000453:epidemiology
keywords: entrapment neuropathy; physical exposure; prospective; upper extremity