Preliminary research needs to be confirmed by more studies.
Medical marijuana shows early promise to reduce opioid use and potential for abuse, suggesting a systematic review of published studies presented at the ANESTHESIOLOGY® 2019 annual meeting. However, much more rigorous scientific research must be carried out to determine whether there are actually benefits of pain relief. for medical marijuana which can relieve chronic pain and outweigh potential risks.
The analysis focused on seven studies, five of which concluded medical cannabis could be associated with benefits such as: decreased opioid overdose rates, decreased opioid use, improved quality of life and improved pain control.
"Overall these results suggest medical cannabis can provide several benefits in reducing opioid abuse, but the study is not a randomized controlled trial comparing cannabis with placebo, which is what we need to determine the true benefits," said Mario Moric, MS, author study major and a biostatistics at Rush University Medical Center, Chicago. "There are other issues to consider as well, including side effects and the fact that these products are often not regulated."
"The long-term effects of medical marijuana are unknown and have not been studied. Early clinical evidence suggests that cannabis may have a detrimental effect on the brain, "said Asokumar Buvanendran, MD, co-author of the study, chair of the American Society of Anesthesiologists (ASA) Committee on Pain Medicine and vice chair of research at Rush University Health services center.
The researchers determined the effect of the combined study was 0.59, which means the benefits of medical marijuana were found to be weaker overall, but significant. Anything above 0 is positive and anything below 0 is negative, with 1 or higher showing a strong effect for this type of research.
Findings from five studies that show positive benefits include a 29% reduction in opioid overdoses in countries with medical marijuana and a reduction in opioid use of 44% to 64% among chronic pain patients. Two other studies found no evidence of a decrease in overall opioid use. One of these studies found that pain actually increased for a small proportion of patients who used cannabis who had more disease and more pain in general. The researchers note that because studies that report positive findings are more likely to be published than negative ones, the results of this new systematic review may be skewed.
At present, 33 states and Washington, D.C., have legalized medical marijuana, but all have their own rules, which vary. Known side effects of cannabis can range from sleepiness to liver damage. Also, a lack of supervision and inconsistent regulations means the ingredients can be different and may include pesticides and other impurities.
Short-term opioids can be useful for pain relief when managed safely and risks are minimized, but longer use needs to be weighed for risks vs. benefits. More than 11 million Americans abuse opioids, more than 2 million have opioid abuse disorders and an estimated 130 people die from opioid overdoses every day, according to the U.S. Department of Health and Human Services. More than 20% of Americans suffer from chronic pain, according to the Centers for Disease Control and Prevention.
"While we await better research on cannabis, pain specialists such as anesthetists can offer many non-opioid drugs and other alternatives to treat chronic pain such as injections, nerve blocks, physical therapy and stimulation of the spinal cord," Dr. Buvanendran.
ASA supports more rigorous research on marijuana and has recently passed two bills that seek to expand research: H.R. 601, Medical Marijuana Research Acts 2019 and S. 2032, Cannabidiol and Marihuana Research Expansion Act.