title: Efficacy and safety of paracetamol for spinal pain and osteoarthritis: systematic review and meta-analysis of randomised placebo controlled trials.
abstract: OBJECTIVE
  To investigate the efficacy and safety of paracetamol (acetaminophen) in the management of spinal pain and osteoarthritis of the hip or knee.
  
  
  METHODS
  Systematic review and meta-analysis.
  
  
  METHODS
  Medline, Embase, AMED, CINAHL, Web of Science, LILACS, International Pharmaceutical Abstracts, and Cochrane Central Register of Controlled Trials from inception to December 2014.
  
  
  METHODS
  Randomised controlled trials comparing the efficacy and safety of paracetamol with placebo for spinal pain (neck or low back pain) and osteoarthritis of the hip or knee.
  
  
  METHODS
  Two independent reviewers extracted data on pain, disability, and quality of life. Secondary outcomes were adverse effects, patient adherence, and use of rescue medication. Pain and disability scores were converted to a scale of 0 (no pain or disability) to 100 (worst possible pain or disability). We calculated weighted mean differences or risk ratios and 95% confidence intervals using a random effects model. The Cochrane Collaboration's tool was used for assessing risk of bias, and the GRADE approach was used to evaluate the quality of evidence and summarise conclusions.
  
  
  RESULTS
  12 reports (13 randomised trials) were included. There was "high quality" evidence that paracetamol is ineffective for reducing pain intensity (weighted mean difference -0.5, 95% confidence interval -2.9 to 1.9) and disability (0.4, -1.7 to 2.5) or improving quality of life (0.4, -0.9 to 1.7) in the short term in people with low back pain. For hip or knee osteoarthritis there was "high quality" evidence that paracetamol provides a significant, although not clinically important, effect on pain (-3.7, -5.5 to -1.9) and disability (-2.9, -4.9 to -0.9) in the short term. The number of patients reporting any adverse event (risk ratio 1.0, 95% confidence interval 0.9 to 1.1), any serious adverse event (1.2, 0.7 to 2.1), or withdrawn from the study because of adverse events (1.2, 0.9 to 1.5) was similar in the paracetamol and placebo groups. Patient adherence to treatment (1.0, 0.9 to 1.1) and use of rescue medication (0.7, 0.4 to 1.3) was also similar between groups. "High quality" evidence showed that patients taking paracetamol are nearly four times more likely to have abnormal results on liver function tests (3.8, 1.9 to 7.4), but the clinical importance of this effect is uncertain.
  
  
  CONCLUSIONS
  Paracetamol is ineffective in the treatment of low back pain and provides minimal short term benefit for people with osteoarthritis. These results support the reconsideration of recommendations to use paracetamol for patients with low back pain and osteoarthritis of the hip or knee in clinical practice guidelines.
  
  
  BACKGROUND
  PROSPERO registration number CRD42013006367.
authors.affiliation: The George Institute for Global Health, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia gmachado@georgeinstitute.org.au.
authors.forename: Gustavo C
authors.initials: GC
authors.lastname: Machado
authors.affiliation: The George Institute for Global Health, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia.
authors.forename: Chris G
authors.initials: CG
authors.lastname: Maher
authors.affiliation: Faculty of Health Sciences, University of Sydney, Sydney, NSW 2141, Australia.
authors.forename: Paulo H
authors.initials: PH
authors.lastname: Ferreira
authors.affiliation: Faculty of Health Sciences, University of Sydney, Sydney, NSW 2141, Australia.
authors.forename: Marina B
authors.initials: MB
authors.lastname: Pinheiro
authors.affiliation: The George Institute for Global Health, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia.
authors.forename: Chung-Wei Christine
authors.initials: CW
authors.lastname: Lin
authors.affiliation: Department of Clinical Pharmacology, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia School of Medical Sciences, Department of Medicine, University of New South Wales, Sydney, NSW 2033, Australia.
authors.forename: Richard O
authors.initials: RO
authors.lastname: Day
authors.affiliation: Faculty of Pharmacy, University of Sydney, Sydney, NSW 2050, Australia Centre for Education and Research on Ageing, Concord Hospital, Sydney, NSW 2139, Australia.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: McLachlan
authors.affiliation: The George Institute for Global Health, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia Institute of Bone and Joint Research, The Kolling Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2065, Australia.
authors.forename: Manuela L
authors.initials: ML
authors.lastname: Ferreira
mesh_terms: D000082:Acetaminophen / Q000627:therapeutic use*; D018712:Analgesics, Non-Narcotic / Q000627:therapeutic use*; D006801:Humans; D017116:Low Back Pain / Q000188:drug therapy*; D019547:Neck Pain / Q000188:drug therapy*; D015207:Osteoarthritis, Hip / Q000188:drug therapy*; D020370:Osteoarthritis, Knee / Q000188:drug therapy*; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome
chemical_list: D018712:Analgesics, Non-Narcotic; D000082:Acetaminophen
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