JAMA Meta-analysis Finds Mixed Results for Medical Marijuana Use

Efficacy, Evidence Levels Vary Widely Across Indications

July 08, 2015 03:22 pm Chris Crawford

In the United States, 23 states and Washington, D.C., have introduced laws to permit medical use of cannabis and cannabinoid-based drugs to treat disease or alleviate symptoms. However, the evidence is still spotty on how successful these drugs are in effectively treating specific conditions.

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So a study(jama.jamanetwork.com) published in the June 23/30 issue of JAMA: the Journal of the American Medical Association analyzed the findings of 79 randomized trials that included more than 6,400 participants. Overall, researchers found there was moderate-quality evidence to support the use of cannabinoids for treating chronic pain but only low-quality evidence regarding the drugs' effectiveness in alleviating other conditions, such as sleep disorders or Tourette syndrome, as well as in reducing nausea and vomiting from chemotherapy.

Study Findings Show Some Promise

Lead author Penny Whiting, Ph.D., of the University of Bristol in Bristol, England, and colleagues conducted a systematic review and meta-analysis of evidence regarding the benefits and adverse events (AEs) linked to medical cannabinoids, drawing from randomized clinical trials on a variety of indications. The researchers found that most studies suggested that cannabinoids were associated with improvements in symptoms, but these associations did not reach statistical significance in all studies.

Story highlights
  • A meta-analysis published in JAMA: the Journal of the American Medical Association found there was moderate-quality evidence to support the use of cannabinoids for treating chronic pain.
  • Low-quality evidence was found for cannabinoid use for sleep disorders or Tourette syndrome and to reduce nausea and vomiting from chemotherapy.
  • Cannabinoids were associated with a much greater risk of adverse events including dizziness, dry mouth, nausea, fatigue, somnolence, euphoria, vomiting, disorientation, drowsiness, confusion, loss of balance and hallucination.

In addition to treating chronic neuropathic and cancer pain, moderate-quality evidence suggested that cannabinoids may be beneficial for spasticity due to multiple sclerosis (sustained muscle contractions or sudden involuntary movements). Also, low-quality evidence suggested that cannabinoids may be able to stimulate appetite for weight gain in patients with HIV infection but that they have no effect on psychosis. Researchers found very low-quality evidence showing they could improve anxiety symptoms, but no studies that addressed the drugs' effects on depression.

Based on data reported in 62 studies, cannabinoids were associated with an increased risk of AEs such as dizziness, dry mouth, nausea, fatigue, somnolence, euphoria, vomiting, disorientation, drowsiness, confusion, loss of balance and hallucination.

No evidence demonstrated a difference in benefits or harms based on the types of cannabinoids studied or the method by which they were consumed by patients. Only two studies evaluated cannabis, showing no evidence that the effects of cannabis differed from those of other cannabinoid-based drugs.

The authors concluded that "further large, robust, randomized clinical trials are needed to confirm the effects of cannabinoids" and to evaluate cannabis itself, given that very little evidence regarding the effects and possible AEs linked to the plant is currently available.

Family Physician Expert Weighs In

Medical Marijuana Out and About Featured at FMX

If the topic of medical marijuana has you intrigued, take note: You can find out more during Family Medicine Experience (FMX), the AAFP's newly renamed annual conference being held this year in Denver. A Medical Marijuana Out and About is scheduled for Sept. 30 from 8 a.m. to noon at CannLabs, a leading cannabis testing laboratory and adviser to commercial, governmental and educational entities focused on the cannabis industry.

In addition to a tour of the host facility, participants will hear a patient who currently uses medical marijuana speak about his experience and what he has learned about what works best.

At the conclusion of the session, participants will be able to:

  • compare the properties of cannabinoids such as cannabidiol and tetrahydrocannabinol,
  • evaluate the available evidence on the use of medical marijuana as a viable treatment option,
  • counsel patients about the risks associated with recreational marijuana use,
  • counsel patients regarding when marijuana is a reasonable therapeutic option, and
  • consider patient perspectives on using medical marijuana and the implications for management of their care.

Fifty spaces are allotted for the event, which offers 1.5 Prescribed CME credits. The fee to participate is $160.

An additional course called Legalization of Marijuana: What Doctors Need to Know will be offered at no charge on Oct. 3 at 1 p.m. and again at 2:15 p.m. in Room 401 of the Colorado Convention Center Room. This session offers 1.0 Prescribed CME credit.

Doris Gundersen, M.D., will discuss how to evaluate available evidence on medical marijuana, establish safeguards to protect patients while weighing the possible consequences of treatment with potential benefits, counsel patients on when marijuana makes sense, and identify resources to keep up-to-date on all related laws.

AAFP member Ashok Kumar, M.D., of San Antonio, who chaired the committee that wrote the AAFP policy concerning medical use of marijuana, told AAFP News he is pleased that the JAMA study is helping disseminate what little research that is available on cannabis and cannabinoids to family physicians who may be seeking information on whether they should be recommending marijuana or other cannabinoids to their patients for medicinal purposes and, if so, for what diseases, conditions or symptoms.

Kumar said he was intrigued by the findings in this meta-analysis that support the use of these agents in the treatment of chronic pain and spasticity (moderate-quality evidence) and for nausea and vomiting associated with cancer chemotherapy, weight gain in patients infected with HIV, sleep disorders, and Tourette syndrome (low-quality evidence).

"I believe given the current evidence, family physicians might be encouraged to use cannabinoids for these conditions when their patients are not helped by more evidence-based medicines," he said.

That said, Kumar added, most family physicians want to practice strong evidence-based medicine, and this meta-analysis showed them no good evidence for using cannabis to alleviate the conditions (e.g., psychosis, depression, anxiety and glaucoma) for which medicinal marijuana is currently approved in some states. The other big drawback is the relatively high incidence of associated AEs, he noted.

Also, because marijuana and cannabinoids are classified by the DEA, with input from the FDA, as Schedule I controlled substances, family physicians cannot currently prescribe the drugs under federal law, said Kumar. Consequently, they have little value as a medical treatment for any condition.

Kumar pointed out that the AAFP policy on marijuana states that the Academy opposes recreational use of marijuana, despite recognizing that several states have passed laws approving limited recreational use. The Academy advocates that additional research be conducted on the effects those laws have on patient and societal health.

The Academy also acknowledges in the policy that states have passed laws approving the medical use of marijuana, but the AAFP does not endorse these laws and will not advocate legalization of medical use until "high quality, patient-centered, evidence-based research" supports doing so.

"To facilitate said research, the AAFP requests that the FDA further review marijuana’s classification as a Schedule I controlled medication," Kumar said.

He added that the AAFP encourages its members to be knowledgeable about the relevant laws of the states in which they practice and consult with their respective chapter staff, medical boards and malpractice carriers for recommended messaging, documentation and clinical advice for patients who are using or inquiring about using marijuana for medical or recreational purposes.

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