Dima Mazen Qato, assistant professor
of pharmacy systems, outcomes and policy, and her colleagues examined changes
in medication use in a nationally representative sample of older adults
between the ages of 62 and 85.
In contrast to many existing studies
of medication use by the elderly, these investigators conducted in-home
interviews to accurately identify what people were actually taking.
According to the study, older adults
using at least five prescription medications (a status known as polypharmacy)
rose from 30.6 percent in 2005 to 35.8 percent in 2011.
Factors that may account for the
rise include the implementation of Medicare Part D, changes
in treatment guidelines, and the increased availability of generics for
many commonly used drugs.
As an example, the use of
simvastatin (Zocor) — the most commonly used prescription medication in the
older adult population, which became available as a generic in 2006 — doubled
from 10.3 percent to 22.5 percent, Qato said. Zocor is used to treat high
cholesterol and may reduce the risk of heart attack and stroke.
Despite limited evidence of their
clinical benefit, dietary supplements are being used by a growing number of
older individuals, the study found — an increase from 51.8 percent to 63.7
percent over the same time period, with nearly a 50 percent growth in the
number of people using multiple supplements. The largest increase was
found in the use of omega-3 fish oils — a dietary supplement with limited
evidence of cardiovascular benefits — which rose from 4.7 percent of
people surveyed in 2005 to 18.6 percent in 2011.
Fifteen potentially life-threatening
drug combinations of the most commonly used medications and supplements in
the study were also identified. Nearly 15 percent of older adults regularly
used at least one of these dangerous drug combinations in 2011, compared to 8
percent in 2005.
More than half of the potential
interactions involved a nonprescription medication or dietary supplement, Qato
said. Preventative cardiovascular medications such as statins
(cholesterol-lowering drugs, particularly simvastatin), anti-platelet drugs
(such as clopidogrel and aspirin, used to prevent blood clots), and supplements
(specifically omega-3 fish oil) accounted for the vast majority of these
interacting drug combinations.
Cardiovascular prevention efforts
and treatment guidelines promoting primary prevention may be undermined by
these interactions, Qato said.
“Many older patients seeking to
improve their cardiovascular health are also regularly using interacting drug
combinations that may worsen cardiovascular risk,” she said.
“For example, the use of clopidogrel
in combination with the proton-pump inhibitor omeprazole, aspirin, or naproxen
— all over-the-counter medications — is associated with an increased risk of
heart attacks, bleeding complications, or death. However, about 1.8 percent —
or 1 million — older adults regularly use clopidogrel in interacting
combinations.”
Health care professionals should
carefully consider the adverse effects of commonly used prescription and
nonprescription medication combinations when treating older adults, Qato said,
and counsel patients about the risks.
“Improving safety in the use of
interacting medication combinations has the potential to reduce preventable,
potentially fatal, adverse drug events,” she said.
While it is not known how many older
adults in the U.S. die of drug interactions, Qato said, “the risk seems to be
growing, and public awareness is lacking.”
Co-authors of the research,
published in JAMA Internal Medicine, are Jocelyn Wilder of UIC; L.
Philip Schumm and Victoria Gillet of the University of Chicago; and
Dr. G. Caleb Alexander of the Johns Hopkins School of Public Health.
The National Social Life, Health and
Aging Project is supported by grants R01AG021487 and R01AG033903 from the
National Institutes of Health, including the National Institutes on Aging, the
Office of Women’s Health Research, the Office of AIDS Research, and the Office
of Behavioral and Social Sciences Research.
