title: Analgesic effects of treatments for non-specific low back pain: a meta-analysis of placebo-controlled randomized trials.
abstract: OBJECTIVE
  Estimates of treatment effects reported in placebo-controlled randomized trials are less subject to bias than those estimates provided by other study designs. The objective of this meta-analysis was to estimate the analgesic effects of treatments for non-specific low back pain reported in placebo-controlled randomized trials.
  
  
  METHODS
  Medline, Embase, Cinahl, PsychInfo and Cochrane Central Register of Controlled Trials databases were searched for eligible trials from earliest records to November 2006. Continuous pain outcomes were converted to a common 0-100 scale and pooled using a random effects model.
  
  
  RESULTS
  A total of 76 trials reporting on 34 treatments were included. Fifty percent of the investigated treatments had statistically significant effects, but for most the effects were small or moderate: 47% had point estimates of effects of <10 points on the 100-point scale, 38% had point estimates from 10 to 20 points and 15% had point estimates of >20 points. Treatments reported to have large effects (>20 points) had been investigated only in a single trial.
  
  
  CONCLUSIONS
  This meta-analysis revealed that the analgesic effects of many treatments for non-specific low back pain are small and that they do not differ in populations with acute or chronic symptoms.
authors.affiliation: The George Institute for International Health, Sydney, Australia.
authors.forename: L A C
authors.initials: LA
authors.lastname: Machado
authors.forename: S J
authors.initials: SJ
authors.lastname: Kamper
authors.forename: R D
authors.initials: RD
authors.lastname: Herbert
authors.forename: C G
authors.initials: CG
authors.lastname: Maher
authors.forename: J H
authors.initials: JH
authors.lastname: McAuley
mesh_terms: D000208:Acute Disease; D000698:Analgesia / Q000379:methods*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D002908:Chronic Disease; D006801:Humans; D017116:Low Back Pain / Q000628:therapy*; D020393:Manipulation, Spinal; D009125:Muscle Relaxants, Central / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D004561:Transcutaneous Electric Nerve Stimulation; D016896:Treatment Outcome
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D009125:Muscle Relaxants, Central