title: The prognosis of acute and persistent low-back pain: a meta-analysis.
abstract: BACKGROUND
  Although low-back pain is a highly prevalent condition, its clinical course remains uncertain. Our main objective was to systematically review the literature on the clinical course of pain and disability in patients with acute and persistent low-back pain. Our secondary objective was to investigate whether pain and disability have similar courses.
  
  
  METHODS
  We performed a meta-analysis of inception cohort studies. We identified eligible studies by searching MEDLINE, Embase and CINAHL. We included prospective studies that enrolled an episode-inception cohort of patients with acute or persistent low-back pain and that measured pain, disability or recovery. Two independent reviewers extracted data and assessed methodologic quality. We used mixed models to determine pooled estimates of pain and disability over time.
  
  
  RESULTS
  Data from 33 discrete cohorts (11 166 participants) were included in the review. The variance-weighted mean pain score (out of a maximum score of 100) was 52 (95% CI 48-57) at baseline, 23 (95% CI 21-25) at 6 weeks, 12 (95% CI 9-15) at 26 weeks and 6 (95% CI 3-10) at 52 weeks after the onset of pain for cohorts with acute pain. Among cohorts with persistent pain, the variance-weighted mean pain score (out of 100) was 51 (95% CI 44-59) at baseline, 33 (95% CI 29-38) at 6 weeks, 26 (95% CI 20-33) at 26 weeks and 23 (95% CI 16-30) at 52 weeks after the onset of pain. The course of disability outcomes was similar to the time course of pain outcomes in the acute pain cohorts, but the pain outcomes were slightly worse than disability outcomes in the persistent pain cohorts.
  
  
  CONCLUSIONS
  Patients who presented with acute or persistent low-back pain improved markedly in the first six weeks. After that time improvement slowed. Low to moderate levels of pain and disability were still present at one year, especially in the cohorts with persistent pain.
authors.affiliation: George Institute for Global Health, the University of Sydney, Sydney, Australia.
authors.forename: Luciola
authors.initials: L
authors.lastname: da C Menezes Costa
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Maher
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Hancock
authors.forename: James H
authors.initials: JH
authors.lastname: McAuley
authors.forename: Robert D
authors.initials: RD
authors.lastname: Herbert
authors.forename: Leonardo O P
authors.initials: LO
authors.lastname: Costa
mesh_terms: D059787:Acute Pain; D059350:Chronic Pain; D004185:Disability Evaluation; D006233:Persons with Disabilities; D006801:Humans; D017116:Low Back Pain / Q000150:complications*; D011379:Prognosis; D011788:Quality of Life; D012044:Regression Analysis