title: Comparison of two different methods for performing combination analysis of force and posture risk factors         in an epidemiological study.
abstract: OBJECTIVE
  This study aimed to introduce a method of simultaneous combination analysis of multiple exposure         parameters for large epidemiological studies of work-related upper-extremity musculoskeletal disorders (MSD) and         compare this analysis method with the conventionally used job-level combination analysis method when applied in         exposure-response analysis of work-related upper-extremity MSD.
  
  
  METHODS
  Health outcome [carpal tunnel syndrome         (CTS)] and physical exposure (forceful exertion and hand/wrist postures) data for 733 subjects were obtained from the         baseline period of a 3-year work-related upper-extremity MSD study. Determinations of CTS cases were done based on a         set of defined criteria. Physical exposure variables of several different types of forceful exertions and three         different hand/wrist postures were collected onsite, processed, and analyzed using both a simultaneous combination and         job-level combination analysis method.
  
  
  RESULTS
  The commonly used job-level combination analysis method resulted in         significantly different combination exposure distributions compared to the simultaneous combination analysis method,         although the absolute differences were small. Both methods showed some significantly higher combined force-posture         exposures among CTS cases than non-cases.
  
  
  CONCLUSIONS
  The simultaneous combination method provides more realistic         distribution information on combined exposure parameters compared to the job-level combination method that has been         commonly used in epidemiological studies. The newly developed simultaneous combination analysis method needs to be used         in larger scale work-related upper-extremity MSD epidemiological studies to test its predictive power compared to the         job-level combination analysis method.
authors.affiliation: Safety & Health Assessment & Research for Prevention-SHARP Program, Washington State Department of Labor and Industries, PO Box 44330, Olympia, WA 98504, USA. baos235@lni.wa.gov
authors.forename: Stephen
authors.initials: S
authors.lastname: Bao
authors.forename: Ninica
authors.initials: N
authors.lastname: Howard
authors.forename: Peregrin
authors.initials: P
authors.lastname: Spielholz
authors.forename: Barbara
authors.initials: B
authors.lastname: Silverstein
authors.forename: Nayak
authors.initials: N
authors.lastname: Polissar
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009140:Musculoskeletal Diseases / Q000453:epidemiology* / Q000503:physiopathology; D011446:Prospective Studies; D012307:Risk Factors