Assessing the Efficacy of Medical Cannabis as a Substitution Therapy for Opioids in Chronic Pain Management in South Africa

Background: The global opioid epidemic has intensified, with a 41% increase in use reported in 2020. Medical cannabis has emerged as a potential adjunct in chronic pain management, with evidence suggesting it may reduce opioid dependence and improve patient outcomes. Objectives: To evaluate the efficacy of medical cannabis in reducing opioid consumption, alleviating pain, and improving quality of life among chronic pain patients in South Africa. Methods: A six-month mixed-methods study was conducted across six sites, enrolling 302 participants (53.3% female, 69.2% White). Medical cannabis was prescribed and outcomes assessed via patient questionnaires and verified pharmacy dispensing records. Repeated-measures analysis, regression, and ANOVA were applied to evaluate temporal changes and treatment effects. Results: At baseline, 99.7% reported opioid use. By six months, 72% achieved ≥50% reduction, with a mean reduction of 93% (SD = 17%); 81.8% achieved complete cessation. Repeated-measures analysis confirmed a linear decline in opioid use over time (Wilk’s λ = 0.047, p < 0.001), with significant reductions at each interval (all p < 0.001). Pain severity scores declined from 3.4 to 3.0, with 64% reporting clinically meaningful relief. Treatment type significantly influenced outcomes (F = 3.87, p = 0.022), with a treatment-by-time interaction (p < 0.001) indicating greater improvements among flower and combination users compared to oil alone. Quality-of-life outcomes also improved, with 83.2% reporting better sleep (p = 0.008) and 78.5% reporting improved physical function (p = 0.012). Conclusions: Medical cannabis use was associated with substantial opioid tapering (p < 0.001), clinically meaningful pain reduction (p = 0.022; interaction p < 0.001), and improvements in sleep and physical function. Flower- and combination-based therapies yielded the greatest benefits. Limitations include the non-randomized, observational design and reliance on self-report measures, which may limit causal inference. Nonetheless, findings support medical cannabis as a promising adjunct in chronic pain treatment, meriting further randomized controlled trials.研究背景：全球阿片类药物危机愈演愈烈，2020年报告显示其使用量增长了41%。医用大麻（medical cannabis）已成为慢性疼痛管理的潜在辅助治疗手段，有证据表明其可降低阿片类药物依赖并改善患者转归。 研究目的：评估医用大麻在南非慢性疼痛患者中减少阿片类药物使用量、缓解疼痛及提升生活质量的有效性。 研究方法：本研究为为期6个月的混合方法研究（mixed-methods study），在6个研究中心开展，共纳入302名受试者（其中女性占53.3%，白人占69.2%）。为受试者开具医用大麻处方，并通过患者问卷与经核实的药房配药记录评估结局指标。采用重复测量分析、回归分析及方差分析（ANOVA）评估随时间变化的趋势与治疗效应。 研究结果：基线时，99.7%的受试者报告存在阿片类药物使用情况。至随访6个月时，72%的受试者阿片类药物使用量较基线降低≥50%，平均降幅达93%（标准差SD=17）；81.8%的受试者实现完全停药。重复测量分析证实，阿片类药物使用量随时间呈线性下降趋势（威尔克λ统计量Wilk’s λ=0.047，p<0.001），各随访时间点的用药量均存在显著降低（所有p<0.001）。疼痛严重程度评分从3.4降至3.0，64%的受试者报告获得具有临床意义的疼痛缓解。治疗类型对结局存在显著影响（F=3.87，p=0.022），且存在治疗-时间交互效应（p<0.001），表明吸食大麻花与联合治疗使用者的改善效果优于单纯使用大麻油者。生活质量相关结局亦得到改善：83.2%的受试者睡眠质量提升（p=0.008），78.5%的受试者躯体功能得到改善（p=0.012）。 研究结论：医用大麻使用与阿片类药物大幅减量（p<0.001）、具有临床意义的疼痛缓解（p=0.022；交互效应p<0.001）以及睡眠与躯体功能改善显著相关。大麻花疗法与联合疗法的获益最为显著。本研究存在一定局限性：采用非随机化观察性研究设计，且依赖受试者自我报告指标，这可能限制了因果推断的可靠性。尽管如此，本研究结果仍支持医用大麻作为慢性疼痛治疗的潜在辅助手段，值得开展进一步的随机对照试验（randomized controlled trial）进行验证。