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Original Investigation
June 23/30, 2015

Cannabinoids for Medical Use: A Systematic Review and Meta-analysis

Author Affiliations
  • 1School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom
  • 2The National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care West at University Hospitals, Bristol NHS Foundation Trust, Bristol, United Kingdom
  • 3Kleijnen Systematic Reviews Ltd, Escrick, York, United Kingdom
  • 4Department of Medical, Oral, and Biotechnological Sciences, University “G. D'Annunzio” of Chieti-Pescara, Chieti, Italy
  • 5Department of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands
  • 6Medical School, Universidad Peruana de Ciencias Aplicadas (UPC), Lima, Peru
  • 7Health Outcomes and Clinical Epidemiology Section, Department of Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
  • 8Department of Pathology, Radboud University Medical Center, Nijmegen, the Netherlands
  • 9Institut für Epidemiologie und kongenitale Erkrankungen, Cepicon GmbH, Hamburg, Germany
  • 10School for Public Health and Primary Care (CAPHRI), Maastricht University, Maastricht, the Netherlands
JAMA. 2015;313(24):2456-2473. doi:10.1001/jama.2015.6358
Abstract

Importance  Cannabis and cannabinoid drugs are widely used to treat disease or alleviate symptoms, but their efficacy for specific indications is not clear.

Objective  To conduct a systematic review of the benefits and adverse events (AEs) of cannabinoids.

Data Sources  Twenty-eight databases from inception to April 2015.

Study Selection  Randomized clinical trials of cannabinoids for the following indications: nausea and vomiting due to chemotherapy, appetite stimulation in HIV/AIDS, chronic pain, spasticity due to multiple sclerosis or paraplegia, depression, anxiety disorder, sleep disorder, psychosis, glaucoma, or Tourette syndrome.

Data Extraction and Synthesis  Study quality was assessed using the Cochrane risk of bias tool. All review stages were conducted independently by 2 reviewers. Where possible, data were pooled using random-effects meta-analysis.

Main Outcomes and Measures  Patient-relevant/disease-specific outcomes, activities of daily living, quality of life, global impression of change, and AEs.

Results  A total of 79 trials (6462 participants) were included; 4 were judged at low risk of bias. Most trials showed improvement in symptoms associated with cannabinoids but these associations did not reach statistical significance in all trials. Compared with placebo, cannabinoids were associated with a greater average number of patients showing a complete nausea and vomiting response (47% vs 20%; odds ratio [OR], 3.82 [95% CI, 1.55-9.42]; 3 trials), reduction in pain (37% vs 31%; OR, 1.41 [95% CI, 0.99-2.00]; 8 trials), a greater average reduction in numerical rating scale pain assessment (on a 0-10-point scale; weighted mean difference [WMD], −0.46 [95% CI, −0.80 to −0.11]; 6 trials), and average reduction in the Ashworth spasticity scale (WMD, −0.12 [95% CI, −0.24 to 0.01]; 5 trials). There was an increased risk of short-term AEs with cannabinoids, including serious AEs. Common AEs included dizziness, dry mouth, nausea, fatigue, somnolence, euphoria, vomiting, disorientation, drowsiness, confusion, loss of balance, and hallucination.

Conclusions and Relevance  There was moderate-quality evidence to support the use of cannabinoids for the treatment of chronic pain and spasticity. There was low-quality evidence suggesting that cannabinoids were associated with improvements in nausea and vomiting due to chemotherapy, weight gain in HIV infection, sleep disorders, and Tourette syndrome. Cannabinoids were associated with an increased risk of short-term AEs.

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