To determine medication and supplement use in 57- to 85-year-old adults, Qato and colleagues used 2005 to 2006 data from the National Social Life, Health, and Aging Project, a population-based survey of Americans living in the community. The 2,976 respondents who completed a medication log used 15,389 prescription, nonprescription, and over-the-counter medications; vitamins; and herbal and alternative medications on a regular basis (every day or every week, for example).

Ninety-one percent of respondents regularly used at least one medication. Prescription medication use was most prevalent in adults ages 75 to 85. Women were more likely than men to take prescription medications and dietary supplements. Cardiovascular medications were the most common prescription and over-the-counter medications used, and alternative therapies for cardiovascular health were also widely used. Use of dietary supplements, including vitamins, was also common.

Use of five or more medications was noted for more than half of all respondents. Almost 70% were taking prescription medications in addition to over-the-counter medications, dietary supplements, or both. Approximately 1 in 25 of the respondents were at risk for major drug-drug interactions. More than half of these possibly life-threatening interactions involved nonprescription medications or supplements, and almost half involved antiplatelet or anticoagulant medications.

This study supports previous work showing that concomitant medication use is increasing. The authors note that health care providers are often unaware of their patients' nonprescription drug use, which can have significant health and economic ramifications when interactions occur. It is particularly important to pay attention to the use of concomitant therapies by older patients, who as a group are the largest consumers of prescription, over-the-counter, and alternative medications and dietary supplements.

Qato DM, et al. JAMA 2008;300(24): 2867-78.