title: Population preventable fraction of bicycle related head injuries.
abstract: OBJECTIVE
  This study analyzes the population attributable fraction (PAF) of bicycle head injuries due to non-helmet use.
  
  
  METHODS
  The concept of the PAF and Levin's formula for its calculation were used to develop mathematical models for estimation of: (i) attributable fraction of bicycle related head injuries in the population due to non-helmet use, (ii) expected proportion of helmeted cases among all head injuries, and (iii) estimate of the helmet use rate in the population based on patient case information. The PAF was calculated for a sample of injuries from Stavanger, Norway.
  
  
  RESULTS
  Levin's formula was used to calculate the PAF. Two additional mathematical models were developed for calculating the expected proportion of helmeted cases and the estimation of the helmet use rate in the population. The P calculation examples for all models were is shown. It was estimated that 133 out of 210 injuries could have been avoided in Stavanger between 1990 and 1996 if all children aged 0-14 had used helmets.
  
  
  CONCLUSIONS
  If applied correctly, the PAF is a valid and useful indicator for the population effects of bicycle helmets. The models developed in this study may help to better interpret and predict the population effects of helmet promotion interventions.
authors.affiliation: Department of Population Health Sciences, National Institute of Public Health, Oslo, Norway. branko.kopjar@samfunnsmed.uio.no
authors.forename: B
authors.initials: B
authors.lastname: Kopjar
mesh_terms: D000293:Adolescent; D001265:Athletic Injuries / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D001642:Bicycling / Q000293:injuries*; D002648:Child; D002669:Child Welfare / Q000706:statistics & numerical data*; D002675:Child, Preschool; D006260:Head Protective Devices / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007223:Infant; D015233:Models, Statistical; D009664:Norway / Q000453:epidemiology; D016017:Odds Ratio; D011159:Population Surveillance; D011446:Prospective Studies; D012042:Registries; D012306:Risk; D012307:Risk Factors