Opioid-sparing effects of medical cannabis or cannabinoids for chronic pain: a systematic review and meta-analysis of randomised and observational studies

Abstract Objective: To assess the efficacy and harms of adding medical cannabis to prescription opioids among people living with chronic pain. Design: Systematic review. Data sources: CENTRAL, EMBASE and MEDLINE. Main outcomes and measures: Opioid dose reduction, pain relief, sleep disturbance, physical and emotional functioning and adverse events. Study selection criteria and methods: We included studies that enrolled patients with chronic pain receiving prescription opioids and explored the impact of adding medical cannabis. We used Grading of Recommendations Assessment, Development