title: Prevention in dangerous industries: does safety certification prevent tree-faller injuries?
abstract: OBJECTIVE
  The aim of this study was to evaluate if safety certification reduces the risk of work injury among experienced manual tree-fallers.
  
  
  METHODS
  This study used a retrospective cohort study design. Experienced manual tree-fallers employed in the Canadian province of British Columbia (N=3251) between 2003-2008 were enumerated from a mandatory faller registry. Registry records with demographic and certification data were linked to workers' compensation claims for injury outcomes. Data were analyzed using discrete time survival analysis over a two-year period, centered on certification date with pre- and post-certification demarcated into four three-month periods. Models were adjusted for demographic, occupation/industry, previous injury, and seasonal/temporal effects.
  
  
  RESULTS
  The relative risk (RR) of work injury during the post certification periods were elevated in comparison to the pre-certification reference period, but the 95% confidence intervals included "1" for all estimates by the end of follow-up, suggesting no statistically significant increased risk of injury. Results were consistent across different outcome measures of acute injury (ie, fracture or amputations) (N=186), musculoskeletal injury (ie, back strain) (N=137), and serious injury claims (ie, long duration, high cost and/or fatal) (N=155).
  
  
  CONCLUSIONS
  Certification did not reduce the risk of work injury among experienced tree-fallers in the province of British Columbia. Non-statistically significant increases in the observed risk of work injury in the months immediately following certification may be attributable to an intervention effect or a methodological limitation related to a lack of individual-level, time-at-risk exposure data.
authors.affiliation: School of Population and Public Health, University of British Columbia, 2206 East Mall, Vancouver, British Columbia, V6T 1Z3, Canada. chris.mcleod@ubc.ca.
authors.forename: Christopher
authors.initials: C
authors.lastname: McLeod
authors.forename: Daniel
authors.initials: D
authors.lastname: Sarkany
authors.forename: Hugh
authors.initials: H
authors.lastname: Davies
authors.forename: Kevin
authors.initials: K
authors.lastname: Lyons
authors.forename: Mieke
authors.initials: M
authors.lastname: Koehoorn
mesh_terms: D000293:Adolescent; D000328:Adult; D001955:British Columbia / Q000453:epidemiology; D002170:Canada; D002568:Certification / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007221:Industry; D008297:Male; D008875:Middle Aged; D009140:Musculoskeletal Diseases / Q000453:epidemiology*; D009784:Occupational Diseases / Q000453:epidemiology*; D060051:Occupational Injuries / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D012449:Safety / Q000592:standards*; D018582:Sick Leave; D012959:Socioeconomic Factors; D014197:Trees; D014942:Workers' Compensation / Q000706:statistics & numerical data*; D055815:Young Adult