Older Patients Teeter Between Drug Over- and Under-Use

SAN FRANCISCO, Oct. 19 -- Medication for Medicare-age patients can be either too much or too little of a good thing.

So said researchers here, who found that the likelihood an older person would be taking an unbeneficial or potentially harmful drug increased as the patient's medication list grew longer.

In contrast, patients taking fewer than eight drugs were more likely to be under-using a potentially helpful medication than to be taking one they didn't need, reported Michael Steinman, M.D., of the San Francisco VA, and colleagues, in the October issue of the Journal of the American Geriatrics Society.

Their study of nearly 200 patients found that only 13% had the balance just right.

"Inappropriate medication use and under-use were common in older people taking five or more medications, with both simultaneously present in more than 40% of patients," they wrote.

Older patients are often on multiple medications, but the line between appropriate medication use and inappropriate polypharmacy is unclear, Dr. Steinman and colleagues noted.

"In older persons with several chronic diseases, prescribing must balance competing tensions between limiting the number of medicines and using all medicines that may be beneficial," they wrote.

"The number of medicines might be limited, because the use of multiple medications is associated with higher likelihood of drug-drug interactions, adverse drug events, hospitalizations, and death," they added. "Alternatively, more medicines might be prescribed, because evidence of efficacy and clinical guidelines support the use of a wide variety of drugs for common diseases such as ischemic heart disease, heart failure, and diabetes mellitus."

The investigators ran a cross-sectional study exploring the relationship between inappropriate prescribing, medication under-use, and the total number of medications used by patients.

The cohort was 196 outpatients ages 65 years and older, each taking at least five medication. The authors measured inappropriate prescribing with a combination of the Beers drugs-to-avoid criteria (2003 update) and subscales of the Medication Appropriateness Index; the latter instrument assesses whether a drug is ineffective, not indicated, or an unnecessary duplication of therapy.

They measured underuse with the Assessment of Underutilization of Medications instrument. The analyses did not include any vitamins, minerals, topical, or herbal medications, or medications taken only as needed.

All but two of the 196 patients were white men, with a mean age of 74.6 years. The patients used an average of 8.1 + 2.5 medications (range 5-17).

The authors found that 128 patients (65%) used one or more inappropriate medications. Of this group, 112 patients (57% of total patients) were taking a total of 171 drugs that were either ineffective, not indicated, or therapeutically redundant.

In addition, more than a third of patients (37%) were taking a total of 91 medications that could cause problems, according to the drugs-to-avoid criteria.

Inappropriate uses included 38 drugs that are never recommended for use in the elderly, 28 drugs that should be avoided in the presence of certain diseases, wrong doses, drug-drug interaction, or combinations.

"Overall, 62 of these 91 medication problems were classified as high severity," the investigators wrote. "Over-the-counter agents accounted for 22 (10%) of inappropriate drugs; approximately half of these were sedating antihistamines."

Conversely, 125 patients (64%) were not getting one or more of 199 drugs that could be beneficial. For example, patients with hypertension weren't on thiazide diuretics, and patients with diabetes and coronary artery disease weren't getting ACE inhibitors. Other drugs patients should have been getting, but weren't, were platelet inhibitors (primarily aspirin) and statins.

"Other commonly omitted medications were agents used for the prevention or treatment of gastrointestinal conditions, diabetes mellitus, osteoporosis, and obstructive pulmonary disease," the authors wrote.

A total of 82 patients (42%) were both taking an inappropriate drug and not getting one they might have benefited from, the authors found. Only 25 patients (13%) had achieved the right balance between the extremes of over- and under-use of medications.

When the data were broken down by the total number of medications taken, the authors found that "the frequency of inappropriate medication use rose sharply from a mean of 0.4 inappropriate medications in patients taking five to six drugs, to 1.1 inappropriate medications in patients taking seven to nine drugs, to 1.9 inappropriate medications in patients taking 10 or more drugs (P<0.001)."

In contrast, under-users were missing out on an average of about one drug per patient, and this number did not change as the total number of drugs taken rose (P=0.26) Overall, patients using fewer than eight medications were more likely to be missing a potentially beneficial drug than to be taking a medication considered inappropriate.

"In patients taking few medications, clinical vigilance and quality efforts should place particular focus on the underuse of medications, Dr. Steinman and colleagues wrote."In contrast, in patients taking large numbers of medications, it is important to expand -- but not substitute -- the focus to include inappropriate medication use."