title: The natural course of carpal tunnel syndrome in a working population.
abstract: OBJECTIVE
  The aim of this study was to assess prevalence, incidence, and persistence of carpal tunnel syndrome (CTS) and associated symptoms over a one-year period in a working population.
  
  
  METHODS
  We conducted a one-year prospective study of 418 active workers in 12 worksites. Detailed health interviews, psychosocial questionnaires, and electrophysiological studies [ie, nerve conduction velocity (NCV) tests] were conducted at baseline and one-year follow-up. Individual-observed exposure assessments of wrist posture, hand activity, and hand forces were conducted.
  
  
  RESULTS
  Prevalence of CTS cases at baseline was 10.8% [95% confidence interval (95% CI) 7.8-13.7%] on the dominant side and 6.0% (95% CI 3.7-87.3%) on the non-dominant side; CTS symptoms were 14.1% (95% CI 10.8-17.5%) and 11.0% (95% CI 8.0-14.0%), respectively. Incidence of CTS cases were 7.5% (95% CI 4.8-10.2%) and 5.6% (95% CI 3.3-7.9%), respectively. Higher proportions of subjects with current symptoms or positive electrophysiological test findings at baseline became CTS cases at one year compared to those with neither (28.6% and 13.9%, respectively, versus 0.5%). One-year persistence of CTS case status was 44.4% (95% CI 29.9-59.0%) for the dominant hand and 52.0% (95% CI 32.4-71.6) for non-dominant hand. There were significant differences at baseline between asymptomatic subjects and CTS cases with respect to higher job demands (P=0.027), lower job satisfaction (P=0.036), lower general health (P=0.0009), higher exposure to vibrating hand tool use (P=0.039), and greater time using a forceful power grip (P=0.035) among cases.
  
  
  CONCLUSIONS
  CTS symptoms more than positive NCV test results alone appear to predict CTS at one year. Persistence of CTS at one year is high.
authors.affiliation: Safety & Health Assessment and Research for Prevention (SHARP), Washington State Department of Labor & Industries, PO Box 44330, Olympia, Washington 98504-4330, USA. silb235@lni.wa.gov
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Silverstein
authors.forename: Z Joyce
authors.initials: ZJ
authors.lastname: Fan
authors.forename: Dave K
authors.initials: DK
authors.lastname: Bonauto
authors.forename: Stephen
authors.initials: S
authors.lastname: Bao
authors.forename: Caroline K
authors.initials: CK
authors.lastname: Smith
authors.forename: Ninica
authors.initials: N
authors.lastname: Howard
authors.forename: Eira
authors.initials: E
authors.lastname: Viikari-Juntura
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002349:Carpal Tunnel Syndrome / Q000453:epidemiology / Q000503:physiopathology* / Q000523:psychology; D016001:Confidence Intervals; D004594:Electrophysiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D007588:Job Satisfaction; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction; D009784:Occupational Diseases / Q000453:epidemiology / Q000503:physiopathology* / Q000523:psychology; D016273:Occupational Exposure / Q000009:adverse effects*; D016272:Occupational Health; D015995:Prevalence; D011446:Prospective Studies; D011594:Psychometrics; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D014861:Washington / Q000453:epidemiology; D016526:Workload