Objective To determine the benefits and harms of medical cannabis and cannabinoids for chronic pain. Design Systematic review and meta-analysis. Data sources MEDLINE, EMBASE, AMED, PsycInfo, CENTRAL, CINAHL, PubMed, Web of Science, Cannabis-Med, Epistemonikos, and trial registries up to January 2021. Study selection Randomised clinical trials of medical cannabis or cannabinoids versus any non-cannabis control for chronic pain at ≥1 month follow-up. Data extraction and synthesis Paired reviewers independently assessed risk of bias and extracted data. We performed random-effects models meta-analyses and used GRADE to assess the certainty of evidence. Results A total of 32 trials with 5174 adult patients were included, 29 of which compared medical cannabis or cannabinoids with placebo. Medical cannabis was administered orally (n=30) or topically (n=2). Clinical populations included chronic non-cancer pain (n=28) and cancer related pain (n=4). Length of follow-up ranged from 1 to 5.5 months. Compared with placebo, non-inhaled medical cannabis probably results in a small increase in the proportion of patients experiencing at least the minimally important difference (MID) of 1 cm (on a 10 cm visual analogue scale (VAS)) in pain relief (modelled risk difference (RD) of 10% (95% confidence interval 5% to 15%), based on a weighted mean difference (WMD) of −0.50 cm (95% CI −0.75 to −0.25 cm, moderate certainty)). Medical cannabis taken orally results in a very small improvement in physical functioning (4% modelled RD (0.1% to 8%) for achieving at least the MID of 10 points on the 100-point SF-36 physical functioning scale, WMD of 1.67 points (0.03 to 3.31, high certainty)), and a small improvement in sleep quality (6% modelled RD (2% to 9%) for achieving at least the MID of 1 cm on a 10 cm VAS, WMD of −0.35 cm (−0.55 to −0.14 cm, high certainty)). Medical cannabis taken orally does not improve emotional, role, or social functioning (high certainty). Moderate certainty evidence shows that medical cannabis taken orally probably results in a small increased risk of transient cognitive impairment (RD 2% (0.1% to 6%)), vomiting (RD 3% (0.4% to 6%)), drowsiness (RD 5% (2% to 8%)), impaired attention (RD 3% (1% to 8%)), and nausea (RD 5% (2% to 8%)), but not diarrhoea; while high certainty evidence shows greater increased risk of dizziness (RD 9% (5% to 14%)) for trials with <3 months follow-up versus RD 28% (18% to 43%) for trials with ≥3 months follow-up; interaction test P=0.003; moderate credibility of subgroup effect). Conclusions Moderate to high certainty evidence shows that non-inhaled medical cannabis or cannabinoids results in a small to very small improvement in pain relief, physical functioning, and sleep quality among patients with chronic pain, along with several transient adverse side effects, compared with placebo. The accompanying BMJ Rapid Recommendation provides contextualised guidance based on this body of evidence. Systematic review registration https://osf.io/3pwn2

Evidence-based medicine is widely promoted for decision-making in health care and is associated with improved patient outcomes. Critics have suggested that evidence-based medicine focuses primarily on groups of patients rather than individuals, but often fail to consider subgroup analyses, N-of-1 trials, and the incorporation of patient values and preferences. Precision medicine has been promoted as an approach to individualize diagnosis and treatment of diseases through genetic, biomarker, phenotypic, and psychosocial characteristics. However, there are often high costs associated with personalized medicine, and high-quality evidence is lacking for effectiveness in many applications. For the potential of personalized medicine to be realized, it must adhere to the principles of evidence-based medicine: (1) evidence in isolation is not sufficient to make clinical decisions—patient’s values and preferences as well as resource implications must be considered, and (2) there is a hierarchy of evidence to guide clinical decision-making and studies at lower risk of bias are likely to provide more trustworthy findings.

Background When evaluating randomized controlled trials (RCTs), clinicians will often refer to the abstract for an initial assessment of the results and to determine whether a full-text review is warranted. Objectives This project aims to assess the reporting quality of RCT abstracts published within the top 5 plastic surgery journals utilizing the Consolidated Standards of Reporting Trials (CONSORT) for abstracts checklist. Methods A computerized database search of OVID MEDLINE was performed. All primary RCTs published within the top 5 plastic surgery journals (by 2016 International Scientific Indexing impact factor) from 2011 to 2018 were included. Two reviewers, blinded to journal and author, independently and in duplicate, scored abstracts employing the 16-item CONSORT for abstracts checklist. Results This review identified 126 RCTs that satisfied the inclusion criteria. Included studies were distributed across 5 journals: Plastic and Reconstructive Surgery (n = 83), JAMA Facial Plastic Surgery (n = 8), Aesthetic Surgery Journal (n = 33), Journal of Reconstructive Microsurgery (n = 2), and the Journal of Hand Surgery–European Volume (n = 0). Mean overall item adherence across all abstracts was 7 (SD ± 2). The most poorly reported items were “trial registration,” “method of randomization,” and “source of trial funding” and appeared in 4%, 2.4%, and 0% of abstracts, respectively. Conclusions There is limited adherence to the CONSORT for abstracts checklist among RCT abstracts published within the top 5 plastic surgery journals. Given the reliance of clinicians on abstract reporting, omitting essential trial details can lead to an inaccurate interpretation of trial results and improper application in clinical practice. Active endorsement of the CONSORT for abstracts checklist is required to improve the quality of RCT abstract reporting.

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