From edibles like gummy bears to traditional marijuana cigarettes, cannabis-based medicines are approved in a number of states to relieve pain, however, the analgesic properties of these products are still unclear and questions continue about their efficacy and about the quality and nature of the research to support their use. Two new studies tackled this issue by analyzing the available research on the use of cannabis-based drugs for the management of chronic pain. The first is a systemic review and meta-analysis of the association between cannabis-based medications and experimental pain outcomes in studies of healthy adults. The second study is a large systematic review and meta-analysis on the use of cannabis-based medications for the management of chronic noncancer pain (CNCP). The review included 104 studies, both controlled and observational, and came to an interesting conclusion.
Try the 11-question quiz above based on the 2 studies and their results. Maybe you will agree with the authors, maybe you won’t, but we guarantee some of the answers might surprise you.
Question 1. Studies on cannabis-based medicines administered to people undergoing experimental pain indicate that the agents appear to do which of the above?
Answer: A. Result in small increases in pain threshold indicating greater pain stimuli are needed to induce pain. Currently available studies indicate that while administration of cannabis-based medications may result in a small increase in pain threshold, they appear to have little effect on pain that is already present.1
Question 2. What percentage of studies performed on cannabis-based medicines for CNCP are considered to be of high-quality?
Answer: A. <15%. In a review of 104 studies that used cannabis-based medicines for CNCP, <15% of studies were considered to be of high quality vs approximately 21% that were considered very low quality, 23% low quality, and 41% moderate quality.2
Question 3. What is the median duration of studies of cannabis-based medicines for chronic pain?
Answer: B. 8 weeks.2Because chronic pain by definition lasts for extended periods (>12 weeks), the short-term nature of most of the studies on cannabis- based medicines means the results provide little insight into what, if any, benefits the drugs may provide with long-term administration.
Question 4. True or false? The longer the studies on cannabis-based interventions lasted, the less of an effect on pain was reported.
Answer: A. True. The longer a study lasted, the less of an effect cannabis-based medicines had on pain.2 This suggests that whatever analgesia the medicines may provide may be reduced over time.
Question 5. In studies on cannabis-based medicines for chronic pain, the greatest pain reduction was reported in studies that lasted for how long?
Answer: A. 1 day2
Question 6. True or false? In studies of patients with chronic pain being treated with both cannabis-based medicines and placebo, there was no difference in dropout rates between the two.
Answer: B. False. Patients receiving cannabis-based medicines were 3.47 times more likely to drop out of studies due to adverse events vs those receiving placebo, while those treated with placebo were slightly more likely to drop out due to lack of efficacy.2
Question 7. Which of the above adverse events are more likely to occur with cannabis-based medicines vs placebo in studies of patients with chronic pain?
Answer: D. All of the above. Dizziness, cognitive disturbance, and confusion and disorientation all have been found to occur more frequently with cannabis-based medicines vs placebo in studies of people with chronic pain.2
Question 8. True or false? In most studies examining the efficacy of cannabis-based medicines for chronic pain, the agents were used as adjuvant treatment rather than as primary treatment for pain or as alternative or replacement medications.
Answer: A. True. In the majority of studies on cannabis-based medicines for chronic pain, these agents were given as add-on medications to patients already using other analgesics. In none of the studies were attempts made to reduce or discontinue patients’ primary analgesics as the cannabis-based medicines were administered.2
Question 9. For which of the above types of chronic pain is there an indication that cannabis-based medicines may provide some benefit?
Answer: C. Multiple sclerosis and other neuropathic pain. Multiple sclerosis and other neuropathic pain are the only forms of chronic pain for which cannabis-based medicines have been shown to be beneficial.2
Question 10. Which statement above about the NNT to attain a 30% reduction in pain in 1 patient with neuropathic pain using cannabis-based medicines appears to be true?
Answer: C. NNT for cannabis-based medicines is higher than for pregabalin and TCAs. The NNT to attain a 30% reduction in neuropathic pain in 1 patient with neuropathic pain using cannabis-based medicines is estimated at 24 vs 7.7 for pregabalin and 3.6 for TCAs.2
Question 11. True or false? In patients with chronic pain, studies have demonstrated that cannabis-based medicines improve levels of functioning.
Answer: B. False. There is little evidence that cannabis-based medicines improve functioning in patients with chronic pain which may be a significant limiting factor in recommending their use.2