BACKGROUND Ecological research suggests that increased access to cannabis may facilitate reductions in opioid use and harms, and medical cannabis patients describe the substitution of opioids with cannabis for pain management. However, there is a lack of research using individual-level data to explore this question. We aimed to investigate the longitudinal association between frequency of cannabis use and illicit opioid use among people who use drugs (PWUD) experiencing chronic pain. METHODS AND FINDINGS This study included data from people in 2 prospective cohorts of PWUD in Vancouver, Canada, who reported major or persistent pain from June 1, 2014, to December 1, 2017 (n = 1,152). We used descriptive statistics to examine reasons for cannabis use and a multivariable generalized linear mixed-effects model to estimate the relationship between daily (once or more per day) cannabis use and daily illicit opioid use. There were 424 (36.8%) women in the study, and the median age at baseline was 49.3 years (IQR 42.3-54.9). In total, 455 (40%) reported daily illicit opioid use, and 410 (36%) reported daily cannabis use during at least one 6-month follow-up period. The most commonly reported therapeutic reasons for cannabis use were pain (36%), sleep (35%), stress (31%), and nausea (30%). After adjusting for demographic characteristics, substance use, and health-related factors, daily cannabis use was associated with significantly lower odds of daily illicit opioid use (adjusted odds ratio 0.50, 95% CI 0.34-0.74, p < 0.001). Limitations of the study included self-reported measures of substance use and chronic pain, and a lack of data for cannabis preparations, dosages, and modes of administration. CONCLUSIONS We observed an independent negative association between frequent cannabis use and frequent illicit opioid use among PWUD with chronic pain. These findings provide longitudinal observational evidence that cannabis may serve as an adjunct to or substitute for illicit opioid use among PWUD with chronic pain.

中文翻译：

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吸毒和报告慢性疼痛的人中大麻和非法阿片类药物的使用频率：一项纵向分析。

背景技术生态学研究表明，增加对大麻的获取可能有助于减少阿片类药物的使用和危害，医学上的大麻患者描述了用大麻代替阿片类药物来治疗疼痛。但是，缺乏使用个人级别的数据来研究这个问题的研究。我们旨在调查在经历慢性疼痛的吸毒人群中，大麻使用频率与非法阿片类药物使用之间的纵向关联。方法和研究结果本研究包括来自加拿大温哥华的2个PWUD前瞻性队列人群的数据，这些人群报告了2014年6月1日至2017年12月1日期间的严重疼痛或持续疼痛（n = 1,152）。我们使用描述性统计数据来检验使用大麻的原因，并使用多变量广义线性混合效应模型来估计每日（每天一次或多次）大麻使用与每日非法阿片类药物使用之间的关系。该研究中有424名（36.8％）妇女，基线时的中位年龄为49.3岁（IQR 42.3-54.9）。在至少一个为期6个月的随访期内，总共有455（40％）次报告每日非法使用阿片类药物，有410（36％）次报告每日使用大麻。报道使用大麻的最常见治疗原因是疼痛（36％），睡眠（35％），压力（31％）和恶心（30％）。在调整了人口统计学特征，物质使用和健康相关因素后，每日使用大麻与每日非法使用阿片类药物的几率显着降低（调整后的几率比为0.50，95％CI为0.34-0.74，p <0.001）。该研究的局限性包括自我报告的物质使用和慢性疼痛的测量方法，以及缺乏有关大麻制剂，剂量和给药方式的数据。结论我们观察到在患有慢性疼痛的PWUD中，经常使用大麻和经常使用非法阿片类药物之间存在独立的负相关性。这些发现提供了纵向的观察证据，表明大麻可在患有慢性疼痛的PWUD中作为非法阿片类药物的辅助剂或替代品。