Off-Label Drug Use Linked to More Adverse Events

By Kelly Young

Edited by David G. Fairchild, MD, MPH, and Jaye Elizabeth Hefner, MD

Off-label use of drugs is associated with higher rates of adverse drug events, according to an observational study in JAMA Internal Medicine.

Researchers gathered information through primary-care-clinic electronic health records in Quebec. The system documents treatment indications and outcomes.

Over 5 years, 45,000 patients filled 150,000 prescriptions, 12% of which were used off-label — that is, for a different purpose than that listed on the drug's label. The rate of adverse events was higher for off-label than on-label use (19.7 vs. 12.5 per 10,000 person-months of observation).

Off-label use was backed by strong evidence in only 20% of cases. Adverse event rates were higher when off-label use wasn't supported by strong evidence, compared with when it was (21.7 vs. 13.2 per 10,000 person-months).

Commentators find the evidence "compelling" that off-label use "increases the risk for an adverse event substantially."