Study: Off-Label Drug Use Causes Higher Rates of Adverse Events

Off-label drug use is associated with a higher incidence of adverse drug events (ADEs), according to a recent study.

“Off-label use of prescription drugs has been identified as an important contributor to preventable adverse drug events (ADEs) in children. Despite concerns regarding adverse outcomes, to date, no systematic investigation of the effects of off-label drug use in adult populations has been performed,” explained the authors of the study.
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For their study, researchers evaluated 46,021 patients who received 151,305 prescribed drugs from primary care clinics in Quebec, Canada between 2005 and 2009. Prescriptions were followed from date of prescription to the date the drug was discontinued, the end of treatment, or until December 30, 2010.

Overall, a total of 3484 ADEs were recorded, with an incidence rate of 13.2 per 10,000 person-months. The incidence rate of ADEs for off-label use was higher than for on-label use (19.7 per 10,000 person-months vs. 12.5 per 10,000 person-months).

Risk of ADE was greater for drugs approved between 1981 and 1995 (14.4 per 10 000 person-months). When women used the drugs, they appeared to be at higher risk as well (14.3 per 10,000 person-months).

Other factors that yielded higher risk included patients receiving 5 to 7 drugs (12.1 per 10,000 person-months), those taking cardiovascular drugs (15.9 per 10,000 person-months), and patients using anti-infectives (66.2 per 10,000 person-months).

“Off-label use of prescription drugs is associated with ADEs. Caution should be exercised in prescribing drugs for off-label uses that lack strong scientific evidence,” they concluded.

“Future electronic health records should be designed to enable postmarket surveillance of treatment indications and treatment outcomes to monitor the safety of on- and off-label uses of drugs,”

-Michelle Canales Butcher

Reference:
Equale T, Buckeridge DL, Verma A, et al. Association of off-label drug use and adverse drug events in an adult population. JAMA Intern Med. 2015 November [epub ahead of print] doi: 10.1001/jamainternmed.2015.6058.