title: Inhaled Cannabis for Chronic Neuropathic Pain: A Meta-analysis of Individual Patient Data.
abstract: Chronic neuropathic pain, the most frequent condition affecting the peripheral nervous system, remains underdiagnosed and difficult to treat. Inhaled cannabis may alleviate chronic neuropathic pain. Our objective was to synthesize the evidence on the use of inhaled cannabis for chronic neuropathic pain. We performed a systematic review and a meta-analysis of individual patient data. We registered our protocol with PROSPERO CRD42011001182. We searched in Cochrane Central, PubMed, EMBASE, and AMED. We considered all randomized controlled trials investigating chronic painful neuropathy and comparing inhaled cannabis with placebo. We pooled treatment effects following a hierarchical random-effects Bayesian responder model for the population-averaged subject-specific effect. Our evidence synthesis of individual patient data from 178 participants with 405 observed responses in 5 randomized controlled trials following patients for days to weeks provides evidence that inhaled cannabis results in short-term reductions in chronic neuropathic pain for 1 in every 5 to 6 patients treated (number needed to treat = 5.6 with a Bayesian 95% credible interval ranging between 3.4 and 14). Our inferences were insensitive to model assumptions, priors, and parameter choices. We caution that the small number of studies and participants, the short follow-up, shortcomings in allocation concealment, and considerable attrition limit the conclusions that can be drawn from the review. The Bayes factor is 332, corresponding to a posterior probability of effect of 99.7%.
  
  
  CONCLUSIONS
  This novel Bayesian meta-analysis of individual patient data from 5 randomized trials suggests that inhaled cannabis may provide short-term relief for 1 in 5 to 6 patients with neuropathic pain. Pragmatic trials are needed to evaluate the long-term benefits and risks of this treatment.
authors.affiliation: Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York. Electronic address: mhandreae@gmail.com.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Andreae
authors.affiliation: Foundation for Integrative AIDS Research, Brooklyn, New York.
authors.forename: George M
authors.initials: GM
authors.lastname: Carter
authors.affiliation: Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York.
authors.forename: Naum
authors.initials: N
authors.lastname: Shaparin
authors.affiliation: Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Suslov
authors.affiliation: Department of Neurosciences, University of California, San Diego, California.
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Ellis
authors.affiliation: Department of Anesthesia and Family Medicine, McGill University, Montréal, Québec, Canada.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Ware
authors.affiliation: AIDS Program, San Francisco General Hospital, University of California, San Francisco, California.
authors.forename: Donald I
authors.initials: DI
authors.lastname: Abrams
authors.affiliation: Department of Physical Medicine and Rehabilitation, VA Northern California and University of California Davis Medical Center, Sacramento, California.
authors.forename: Hannah
authors.initials: H
authors.lastname: Prasad
authors.affiliation: Department of Physical Medicine and Rehabilitation, VA Northern California and University of California Davis Medical Center, Sacramento, California.
authors.forename: Barth
authors.initials: B
authors.lastname: Wilsey
authors.affiliation: Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Debbie
authors.initials: D
authors.lastname: Indyk
authors.affiliation: Teachers College, Columbia University, New York, New York.
authors.forename: Matthew
authors.initials: M
authors.lastname: Johnson
authors.affiliation: Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Henry S
authors.initials: HS
authors.lastname: Sacks
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D001499:Bayes Theorem; D002188:Cannabis; D059350:Chronic Pain / Q000188:drug therapy* / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D064086:Medical Marijuana / Q000008:administration & dosage / Q000627:therapeutic use*; D008875:Middle Aged; D010146:Pain / Q000188:drug therapy* / Q000453:epidemiology; D017933:Peripheral Nervous System / Q000187:drug effects*; D010523:Peripheral Nervous System Diseases / Q000188:drug therapy* / Q000453:epidemiology; D016032:Randomized Controlled Trials as Topic; D055815:Young Adult
chemical_list: D064086:Medical Marijuana
keywords: Bayesian analysis; Cannabis; chronic pain; human immunodeficiency virus; meta-analysis; meta-analysis of individual patient data; neuropathy; painful; polyneuropathy