To the Editor Bachhuber et al1 found that states with legalized medical marijuana and those that had longer periods of legalized medical marijuana had lower adjusted opioid analgesic mortality rates than those that did not. Although they acknowledged that mechanisms underlying these relationships are speculative, the one receiving the most attention was that medical marijuana may reduce patients’ reliance on opioid pain medications, thereby reducing their mortality risk. The authors noted that one limitation of their analyses was that they were “ecologic” (ie, linking state-level variables), so they “cannot adjust for characteristics of individuals within the states….”1(p1671) We would suggest that the primary drawback of the ecologic analyses is that they provide no information whether individual pain patients who use marijuana have a lower or higher opioid analgesic mortality risk.
Finney JW, Humphreys K, Harris AHS. What Ecologic Analyses Cannot Tell Us About Medical Marijuana Legalization and Opioid Pain Medication Mortality. JAMA Intern Med. 2015;175(4):655-656. doi:10.1001/jamainternmed.2014.8006