title: Low back pain after traffic collisions: a population-based cohort study.
abstract: METHODS
  A population-based, incidence cohort study was conducted.
  
  
  OBJECTIVE
  To measure the incidence and prognosis for collision-related low back pain before and after a change in the insurance compensation system.
  
  
  BACKGROUND
  Low back pain is a common and costly occupational injury. It also occurs after traffic collisions, but less is known about its frequency and recovery in this setting.
  
  
  METHODS
  An incidence cohort of 4473 low back pain injury claims was formed between July 1, 1994 and December 31, 1995 in Saskatchewan. On January 1, 1995 the public insurance system changed from a tort system to a no-fault system, eliminating compensation for pain and suffering. The incidence of claims and the time to claim closure were calculated before and after this change. Prognostic models were built using baseline and follow-up data.
  
  
  RESULTS
  The 6-month incidence of claims decreased from 256 to 176 per 100,000 after the insurance change. The median time to claim closure dropped from 505 days for tort claims to 210 days and 216 days for claims made during the first and second 6 months of the no-fault period. Improvements in bodily pain and physical functioning and the absence of depressive symptoms were associated with faster claim closure. High pain intensity, female gender, full-time employment, concentration problems, and lawyer involvement early in the claim process delayed claim closure.
  
  
  CONCLUSIONS
  Low back pain is a common traffic injury with a prolonged recovery. Its incidence and prognosis are affected by multiple factors, including the type of compensation system. Our study suggests that biopsychosocial factors are important in determining prognosis.
authors.affiliation: Epidemiology Program and the Alberta Centre for Injury Control and Research, Department of Public Health Sciences, University of Alberta, Edmonton, Canada. dcassidy@ualberta.ca
authors.forename: J David
authors.initials: JD
authors.lastname: Cassidy
authors.forename: Linda
authors.initials: L
authors.lastname: Carroll
authors.forename: Pierre
authors.initials: P
authors.lastname: Côté
authors.forename: Anita
authors.initials: A
authors.lastname: Berglund
authors.forename: Ake
authors.initials: A
authors.lastname: Nygren
mesh_terms: D000063:Accidents, Traffic; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007346:Insurance, Accident / Q000706:statistics & numerical data; D017116:Low Back Pain / Q000191:economics / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012525:Saskatchewan / Q000453:epidemiology; D012737:Sex Factors; D013997:Time Factors