Maya E. O'Neil, PhD; Shannon M. Nugent, PhD; Benjamin J. Morasco, PhD; Michele Freeman, MPH; Allison Low, BA; Karli Kondo, PhD; Bernadette Zakher, MBBS; Camille Elven, MD; Makalapua Motu'apuaka, BA; Robin Paynter, MLIS; Devan Kansagara, MD, MCR
Disclaimer: The views and conclusions expressed in this article are those of the authors, who are responsible for its content, and do not necessarily represent the views of the U.S. Department of Veterans Affairs or the U.S. government. Therefore, no statement should be construed as an official position of the U.S. Department of Veterans Affairs.
Financial Support: By the U.S. Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Quality Enhancement Research Initiative.
Disclosures: Dr. Morasco reports grants from the U.S. Department of Veterans Affairs during the conduct of the study. Authors not named here have disclosed no conflicts of interest. Disclosures can also be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M17-0477.
Editors' Disclosures: Christine Laine, MD, MPH, Editor in Chief, reports that she has no financial relationships or interests to disclose. Darren B. Taichman, MD, PhD, Executive Deputy Editor, reports that he has no financial relationships or interests to disclose. Cynthia D. Mulrow, MD, MSc, Senior Deputy Editor, reports that she has no relationships or interests to disclose. Deborah Cotton, MD, MPH, Deputy Editor, reports that she has no financial relationships or interest to disclose. Jaya K. Rao, MD, MHS, Deputy Editor, reports that she has stock holdings/options in Eli Lilly and Pfizer. Sankey V. Williams, MD, Deputy Editor, reports that he has no financial relationships or interests to disclose. Catharine B. Stack, PhD, MS, Deputy Editor for Statistics, reports that she has stock holdings in Pfizer and Johnson & Johnson.
Reproducible Research Statement:Study protocol: Available at www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42016033623. Statistical code: Not applicable. Data set: Available in the Supplement.
Requests for Single Reprints: Maya E. O'Neil, PhD, VA Portland Health Care System, RD 66, 3710 Southwest U.S. Veterans Hospital Road, Portland, OR 97239; e-mail, email@example.com.
Current Author Addresses: Drs. O'Neil, Nugent, and Morasco: VA Portland Health Care System, RD 66, 3710 Southwest U.S. Veterans Hospital Road, Portland, OR 97239.
Ms. Freeman, Ms. Low, Dr. Kondo, Ms. Motu'apuaka, and Ms. Paynter: VA Portland Health Care System, RD 71, 3710 Southwest U.S. Veterans Hospital Road, Portland, OR 97239.
Ms. Zakher and Dr. Elven: Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239.
Dr. Kansagara: VA Portland Health Care System, P3MED, 3710 Southwest U.S. Veterans Hospital Road, Portland, OR 97239.
Author Contributions: Conception and design: M.E. O'Neil, S.M. Nugent, B.J. Morasco, M. Freeman, A. Low, K. Kondo, M. Motu'apuaka, D. Kansagara.
Analysis and interpretation of the data: M.E. O'Neil, S.M. Nugent, B.J. Morasco, M. Freeman, A. Low, K. Kondo, B. Zakher, C. Elven, M. Motu'apuaka, D. Kansagara.
Drafting of the article: M.E. O'Neil, S.M. Nugent, M. Freeman, A. Low, K. Kondo, D. Kansagara.
Critical revision for important intellectual content: M.E. O'Neil; B.J. Morasco, M. Freeman, A. Low, K. Kondo, C. Elven, D. Kansagara.
Final approval of the article: M.E. O'Neil, S.M. Nugent, B.J. Morasco, M. Freeman, A. Low, K. Kondo, B. Zakher, C. Elven, M. Motu'apuaka, R. Paynter, D. Kansagara.
Obtaining of funding: D. Kansagara.
Administrative, technical, or logistic support: M. Freeman, A. Low, M. Motu'apuaka, R. Paynter.
Collection and assembly of data: M.E. O'Neil, S.M. Nugent, B.J. Morasco, M. Freeman, A. Low, K. Kondo, B. Zakher, C. Elven, M. Motu'apuaka, R. Paynter, D. Kansagara.
Cannabis is available from medical dispensaries for treating posttraumatic stress disorder (PTSD) in many states of the union, yet its efficacy in treating PTSD symptoms remains uncertain.
To identify ongoing studies and review existing evidence regarding the benefits and harms of plant-based cannabis preparations in treating PTSD in adults.
MEDLINE, the Cochrane Library, and other sources from database inception to March 2017.
English-language systematic reviews, trials, and observational studies with a control group that reported PTSD symptoms and adverse effects of plant-based cannabis use in adults with PTSD.
Study data extracted by 1 investigator was checked by a second reviewer; 2 reviewers independently assessed study quality, and the investigator group graded the overall strength of evidence by using standard criteria.
Two systematic reviews, 3 observational studies, and no randomized trials were found. The systematic reviews reported insufficient evidence to draw conclusions about benefits and harms. The observational studies found that compared with nonuse, cannabis did not reduce PTSD symptoms. Studies had medium and high risk of bias, and overall evidence was judged insufficient. Two randomized trials and 6 other studies examining outcomes of cannabis use in patients with PTSD are ongoing and are expected to be completed within 3 years.
Very scant evidence with medium to high risk of bias.
Evidence is insufficient to draw conclusions about the benefits and harms of plant-based cannabis preparations in patients with PTSD, but several ongoing studies may soon provide important results.
U.S. Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Quality Enhancement Research Initiative. (PROSPERO: CRD42016033623)
Literature flow diagram.
Central = The Cochrane Central Register of Controlled Trials; CDSR = Cochrane Database of Systematic Reviews; DARE = The Database of Abstracts of Reviews of Effects; EBMR = Evidence-Based Medicine Reviews; HTA = Health Technology Assessments; PILOTS = Published International Literature on Traumatic Stress.
Table 1. Studies of the Effects of Cannabis on PTSD Symptoms
Table 2. Ongoing Studies of Cannabis for PTSD*
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Maya E. O'Neil, Shannon M. Nugent, Benjamin J. Morasco, Michele Freeman, Allison Low, Karli Kondo, et al. Benefits and Harms of Plant-Based Cannabis for Posttraumatic Stress Disorder: A Systematic Review. Ann Intern Med. 2017;167:332–340. doi: 10.7326/M17-0477
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Published: Ann Intern Med. 2017;167(5):332-340.
Published at www.annals.org on 15 August 2017
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