为了系统评估大麻、大麻素和以大麻为基础的药物与人类健康之间的关联的可信度和确定度，采用伞形审查的方法。使用PubMed、PsychInfo和Embase数据库检索至2022年2月9日的文献。筛选纳入包含对大麻、大麻素或以大麻为基础的药物的疗效和安全性进行系统回顾与荟萃分析的观察性研究和随机对照试验（RCT）。 根据“有说服力”、“高度暗示性”、“暗示性”、“弱”或“无显著性”（观察性研究）及GRADE（推荐、评估、发展和评估）（RCT）对可信度进行分级评定。使用AMSTAR 2（用于评估系统回顾的测量工具2）评估研究质量。进行敏感性分析。纳入了101个荟萃分析（观察性研究=50，RCT=51）（AMSTAR 2评级为高质量33个，中等质量31个，低质量32个，严重低质量5个）。来自高到中度可信度的RCT支持，大麻为基础的药物在混合疾病患者中增加了与中枢神经系统相关的不良事件（等效比值2.84（95%置信区间2.16至3.73）），心理效应（3.07（1.79至5.26））以及视觉障碍（3.00（1.79至5.03））（GRADE=高），改善了恶心/呕吐、疼痛、痉挛等症状，但增加了精神病、胃肠道不良反应和嗜睡等副作用（GRADE=中等）。大麻二酚改善了癫痫发作的50%减少（0.59（0.38至0.92））和癫痫发作事件（0.59（0.36至0.96））（GRADE=高），但增加了肺炎、胃肠道不良反应和嗜睡等副作用（GRADE=中等）。对于慢性疼痛，大麻为基础的药物或大麻素可使疼痛减少30%（0.59（0.37至0.93），GRADE=高），适用于不同疾病条件（n=7），但会增加心理压力。对于癫痫，大麻二酚增加了腹泻的风险（2.25（1.33至3.81）），对睡眠没有影响（GRADE=高），减少了不同人群和测量方法的癫痫发作（n=7），改善了整体印象（n=2），生活质量提高，但增加了嗜睡的风险（GRADE=中等）。在普通人群中，大麻恶化了阳性精神症状（5.21（3.36至8.01））和总精神症状（7.49（5.31至10.42））（GRADE=高），增加了阴性精神症状和认知力（n=11）（GRADE=中等）。在健康人群中，大麻素提高了疼痛阈值（0.74（0.59至0.91）），降低了不愉快感（0.60（0.41至0.88））（GRADE=高）。对于炎症性肠病，大麻素可以提高生活质量（0.34（0.22至0.53））（GRADE=高）。对于多发性硬化症，大麻素可以减轻痉挛和疼痛症状，但会增加头晕、口干、恶心和嗜睡的风险（GRADE=中等）。对于癌症，大麻素可以改善睡眠障碍，但伴有胃肠道不良反应（n=2）（GRADE=中等）。无论是大麻为基础的药物、大麻还是大麻素在各种疾病条件下的耐受性都较差（GRADE=中等）。根据观察性研究（主要和敏感性分析），对于怀孕妇女，新生儿低体重（1.43（1.27至1.62））和矮小儿（1.61（1.41至1.83））；对于驾车人群，车祸（1.27（1.21至1.34））；对于一般人群，精神病（1.71（1.47至2.00））等不良结果提供了有说服力的证据。在青少年和早期成年期、易患或患有精神健康障碍的人群、怀孕期间以及驾车前和驾车期间应避免使用大麻的证据堪称确凿或收敛。卡巴胶酮对癫痫患者有效。在多发性硬化症、慢性疼痛、炎症性肠病和姑息医学中，大麻为基础的药物是有效的，但不乏不良反应。PROSPERO CRD42018093045。无。© 作者（或其雇主）2019。依据CC BY-NC许可进行再利用。不得进行商业再利用。详见相关的权利和权限。由BMJ出版。

To systematically assess credibility and certainty of associations between cannabis, cannabinoids, and cannabis based medicines and human health, from observational studies and randomised controlled trials (RCTs).Umbrella review.PubMed, PsychInfo, Embase, up to 9 February 2022.Systematic reviews with meta-analyses of observational studies and RCTs that have reported on the efficacy and safety of cannabis, cannabinoids, or cannabis based medicines were included. Credibility was graded according to convincing, highly suggestive, suggestive, weak, or not significant (observational evidence), and by GRADE (Grading of Recommendations, Assessment, Development and Evaluations) (RCTs). Quality was assessed with AMSTAR 2 (A Measurement Tool to Assess Systematic Reviews 2). Sensitivity analyses were conducted.101 meta-analyses were included (observational=50, RCTs=51) (AMSTAR 2 high 33, moderate 31, low 32, or critically low 5). From RCTs supported by high to moderate certainty, cannabis based medicines increased adverse events related to the central nervous system (equivalent odds ratio 2.84 (95% confidence interval 2.16 to 3.73)), psychological effects (3.07 (1.79 to 5.26)), and vision (3.00 (1.79 to 5.03)) in people with mixed conditions (GRADE=high), improved nausea/vomit, pain, spasticity, but increased psychiatric, gastrointestinal adverse events, and somnolence among others (GRADE=moderate). Cannabidiol improved 50% reduction of seizures (0.59 (0.38 to 0.92)) and seizure events (0.59 (0.36 to 0.96)) (GRADE=high), but increased pneumonia, gastrointestinal adverse events, and somnolence (GRADE=moderate). For chronic pain, cannabis based medicines or cannabinoids reduced pain by 30% (0.59 (0.37 to 0.93), GRADE=high), across different conditions (n=7), but increased psychological distress. For epilepsy, cannabidiol increased risk of diarrhoea (2.25 (1.33 to 3.81)), had no effect on sleep disruption (GRADE=high), reduced seizures across different populations and measures (n=7), improved global impression (n=2), quality of life, and increased risk of somnolence (GRADE=moderate). In the general population, cannabis worsened positive psychotic symptoms (5.21 (3.36 to 8.01)) and total psychiatric symptoms (7.49 (5.31 to 10.42)) (GRADE=high), negative psychotic symptoms, and cognition (n=11) (GRADE=moderate). In healthy people, cannabinoids improved pain threshold (0.74 (0.59 to 0.91)), unpleasantness (0.60 (0.41 to 0.88)) (GRADE=high). For inflammatory bowel disease, cannabinoids improved quality of life (0.34 (0.22 to 0.53) (GRADE=high). For multiple sclerosis, cannabinoids improved spasticity, pain, but increased risk of dizziness, dry mouth, nausea, somnolence (GRADE=moderate). For cancer, cannabinoids improved sleep disruption, but had gastrointestinal adverse events (n=2) (GRADE=moderate). Cannabis based medicines, cannabis, and cannabinoids resulted in poor tolerability across various conditions (GRADE=moderate). Evidence was convincing from observational studies (main and sensitivity analyses) in pregnant women, small for gestational age (1.61 (1.41 to 1.83)), low birth weight (1.43 (1.27 to 1.62)); in drivers, car crash (1.27 (1.21 to 1.34)); and in the general population, psychosis (1.71 (1.47 to 2.00)). Harmful effects were noted for additional neonatal outcomes, outcomes related to car crash, outcomes in the general population including psychotic symptoms, suicide attempt, depression, and mania, and impaired cognition in healthy cannabis users (all suggestive to highly suggestive).Convincing or converging evidence supports avoidance of cannabis during adolescence and early adulthood, in people prone to or with mental health disorders, in pregnancy and before and while driving. Cannabidiol is effective in people with epilepsy. Cannabis based medicines are effective in people with multiple sclerosis, chronic pain, inflammatory bowel disease, and in palliative medicine but not without adverse events.PROSPERO CRD42018093045.None.© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.