What Evidence Supports Marijuana Use for Medical Indications: Not Much

More than 20 states have legalized marijuana use for various medical conditions. To explore the evidence for medical marijuana efficacy, researchers conducted a systematic review and meta-analysis of 79 trials that involved 6462 patients. Four studies were judged to be at low risk of bias, whereas 55 studies were judged to be at high risk, mostly because of incomplete outcomes reporting. Although most studies were reported as double-blind, their blinding methods were considered inadequate in many cases.