Published research indicates that many older adults in the United States use prescription and over-the-counter (OTC) medications and dietary supplements, but this can increase their risks for polypharmacy and adverse drug events. Many medications that are commonly used by older adults, such as antiplatelets, anticoagulants, statins, and NSAIDs, are associated with serious drug-drug interactions, which may further increase this risk.

Previously, investigators have examined the use of prescription and OTC medications and dietary supplements among older adults in the U.S. These studies have revealed that more than half of older adults concurrently use prescription and nonprescription medications, including dietary supplements. “A significant number of older adults use interacting medications or dietary supplements that can potentially increase their risks for adverse drug events,” explains Dima M. Qato, PharmD, MPH, PhD.

With new drugs continuing to emerge on the market and the increasing availability of generic and OTC products, it is becoming even more important to examine the potential safety concerns associated with commonly used drugs among older adults. Recently collected data may underestimate medication use and potential adverse effects because they do not always capture information on OTC medications and dietary supplements.

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A Closer Look

For a study published in JAMA Internal Medicine, Dr. Qato and colleagues examined nationally representative data from the second wave of the National Social Life, Health, and Aging Project, which included data from 2010-2011. The study sought to update estimates of medication use, concurrent use, and drug-drug interactions among older adults throughout the country and explored if there were any changes in risks of drug-drug interactions since the last time data was collected in 2005-2006. The total study cohort consisted of 2,351 participants in 2005-2006 and 2,206 in 2010-2011.

Results of the analysis showed that the rate of older adults using at least one prescription medication increased slightly from 84.1% in 2005-2006 to 87.7% in 2010-2011. Concurrent use of at least five prescription medications increased from 30.6% to 35.8% between the cohorts. Use of OTC medications declined from 44.4% to 37.9%, but use of dietary supplements increased from 51.8% to 63.7% during the study period.

The study also showed that there were clinically significant increases in the use of statins, antiplatelets, and omega-3 fish oils during the study period. In 2010-2011, about 15.1% of older adults were at risk for a potential major drug-drug interaction, compared with a rate of about 8.4% that was seen in the 2005-2006 cohort (Table). Most of these interacting regimens involved medications and dietary supplements that were increasingly used in patients in 2010-2011. The study team reported that older adults nearly doubled their use of multiple medications and dietary supplements from 2005-2006 to 2010-2011. About one in six older adults may be at risk for a major drug-drug interaction.


Analyzing Commonly Used Drugs

Authors of the study also identified 93 potential drug-drug interactions that involved prescription and OTC medications and supplements based on the 20 most commonly used medications and 20 of the most commonly used supplements. Among these products, 15 interacting combinations were classified as being a potentially major or life-threatening. Each of these products was reportedly used by at least one respondent in the study sample. Several factors may have contributed to the results, such as the implementation of Medicare Part D, changes to clinical guidelines, and changing market dynamics, such as new therapies being brought to market and patents expiring.

A Growing Health Issue

According to Dr. Qato, findings from the study suggest that the unsafe use of multiple drugs among older adults is a growing public health problem. “Physicians and healthcare professionals should carefully consider the adverse effects of commonly used prescription and nonprescription medication combinations when treating and counseling older adults,” she says. “Efforts are needed to regularly monitor patients for all of the drugs they take rather than just prescription medications. Patients also need to be counseled about potential risks they can incur by using multiple drugs. This is a critical patient safety issue that needs to be dealt with proactively.”

By focusing on improving the safe use of multiple medications, physicians can potentially help reduce preventable adverse drug events that have been linked to drugs that are commonly and increasingly used among older American adults, according to Dr. Qato. “Clinicians need to become more aware of this issue and think about the risks that are associated with concurrent use of interacting medications,” she says. “These efforts may include incorporating the interaction effects of commonly used medications—including OTC medications and dietary supplements—in treatment guidelines.”