title: Prognosis for patients with chronic low back pain: inception cohort study.
abstract: OBJECTIVE
  To describe the course of chronic low back pain in an inception cohort and to identify prognostic markers at the onset of chronicity.
  
  
  METHODS
  Inception cohort study with one year follow-up.
  
  
  METHODS
  Primary care clinics in Sydney, Australia.
  
  
  METHODS
  The study sample was a subcohort of an inception cohort of 973 consecutive patients presenting to primary care with acute low back pain (<2 weeks' duration). 406 participants whose pain persisted for three months formed the inception cohort of patients with chronic low back pain.
  
  
  METHODS
  Outcomes and putative predictors measured at initial presentation, onset of chronicity (study entry), and follow-up at nine and 12 months. Recovery was determined from measures of pain intensity, disability, and work status. The association between potential prognostic factors and time to recovery was modelled with Cox regression.
  
  
  RESULTS
  Completeness of follow-up was 97% of total person time for all outcomes. The cumulative probability of being pain-free was 35% at nine months and 42% at 12 months and for complete recovery was 35% at nine months and 41% at 12 months. Of the 259 participants who had not recovered from pain related disability at entry to the chronic study, 47% had recovered by 12 months. Previous sick leave due to low back pain, high disability levels or high pain intensity at onset of chronicity, low levels of education, greater perceived risk of persistent pain, and being born outside Australia were associated with delayed recovery.
  
  
  CONCLUSIONS
  More than one third of patients with recent onset, non-radicular chronic low back pain recover within 12 months. The prognosis is less favourable for those who have taken previous sick leave for low back pain, have high disability levels or high pain intensity at onset of chronic low back pain, have lower education, perceive themselves as having a high risk of persistent pain, and were born outside Australia.
authors.affiliation: George Institute for International Health, University of Sydney. lmenezes@george.org.au
authors.forename: Luciola da C Menezes
authors.initials: Lda C
authors.lastname: Costa
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Maher
authors.forename: James H
authors.initials: JH
authors.lastname: McAuley
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Hancock
authors.forename: Robert D
authors.initials: RD
authors.lastname: Herbert
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Refshauge
authors.forename: Nicholas
authors.initials: N
authors.lastname: Henschke
mesh_terms: D000328:Adult; D001294:Attitude to Health; D002908:Chronic Disease; D015331:Cohort Studies; D006233:Persons with Disabilities / Q000706:statistics & numerical data; D004522:Educational Status; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis* / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D009517:New South Wales; D011320:Primary Health Care / Q000706:statistics & numerical data; D011379:Prognosis; D012307:Risk Factors; D018582:Sick Leave / Q000706:statistics & numerical data