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One in six older adults at risk for major drug interaction

Older adults' use of prescription medications and dietary supplements, and their concurrent use of interacting medications, has increased, according to recently published findings.

These increases put older adults at risk for adverse drug events, Dima M. Qato, PharmD, MPH, PhD, department of pharmacy systems, outcomes, and policy, College of Pharmacy, University of Illinois at Chicago, and colleagues reported in JAMA Internal Medicine.

"During the past decade, various regulatory and market events have taken place that may have affected medication use among older adults, including the implementation of Medicare Part D, the introduction of dozens of new drugs to market, and the increasing availability of generic and OTC products," Qato and colleagues wrote. "In addition to these forces, a growing number of safety concerns associated with commonly used medications, including statins, NSAIDs, proton pump inhibitors, and medication combinations, have emerged that may also have affected medication and supplement use among older adults."

The researchers cited recent findings from the National Health and Nutrition Examination Survey which indicated that prescription medication and polypharmacy has increased in older adult. These increases may be conservative estimates, according to Qato and colleagues.

They analyzed in-home interviews from a longitudinal, nationally representative sample of community-dwelling adults aged 62 to 85 years old. The interviews involved direct medication inspection and were conducted twice, once in 2005 to 2006 and again in 2010 to 2011.

Qato and colleagues conducted 4,557 interviews: 2,351 in the first wave and 2,206 in the second.

Data showed that use of at least one prescription medication increased from 84.1% in 2005 to 2006 to 87.7% in 2010 to 2011 (P = .003). Concurrent use of at least five prescription medications increased from 30.6% to 35.8% (P = .02).

OTC medication use decreased from 44.4% to 37.9% (P < .001) and dietary supplement use increased from 51.8% to 63.7% (P < .001). Qato and colleagues also identified increases in omega-3 fish oil use (4.7% to 18.6%; P < .05), antiplatelets (32.8% to 43%; P < .05) and statins (33.8% to 46.2%; P < .05).

In addition, the researchers reported that risk for a potential major drug-drug interaction increased from 8.4% to 15.1% (P < .001).

"Older adults are increasingly using multiple medications and dietary supplements, and the use of interacting medication regimens has increased over time," Qato and colleagues concluded. "Approximately one in six older adults may be at risk for a major drug-drug interaction. Efforts that focus on improving the safe use of multiple medications have the potential to reduce preventable adverse drug events associated with medications commonly and increasingly used among older adults in the United States." – by Chelsea Frajerman Pardes

Disclosures: Please see the full study for a complete list of all authors’ relevant financial disclosures.