Drugs may confer serious risks along with substantial therapeutic benefits. The aging of the population and the trend toward increased outpatient drug use—and hence the likely rise in adverse events—underscore the need for ongoing surveillance of outpatient drug safety. Yet clinical practice guidelines provide little direction on the treatment of elderly patients and on how to balance and prioritize medication use in patients with multiple disorders. Recent reports have highlighted the challenges and pitfalls of prescribing for elderly patients.
ADVERSE DRUG EVENTS
Patients aged 65 years or older constitute a disproportionate percentage of the more than 700,000 persons who visit emergency departments (EDs) annually as a result of adverse drug events (ADEs), according to a new study funded by the CDC, the FDA, and the US Consumer Product Safety Commission.1 Although older persons make up 12% of the American population, they accounted for more than 25% of ADEs and nearly half of the events that required hospitalization. The estimated annual rate of ADEs was 2.4 per 1000 population, but the rate increased to 4.9 per 1000 in patients aged 65 years or older and peaked at 6.8 per 1000 for those aged 85 years or older. Persons aged 65 years or older were nearly 7 times as likely to require hospitalization as younger persons.
Among all patients who were hospitalized, most ADEs were the result of unintentional overdoses, and two thirds of those were attributable to toxicity from drugs that require regular monitoring. Intentional self-harm, drug therapeutic failures, drug withdrawal, and drug abuse were excluded.
The authors found that 16 of the 18 drugs that most commonly caused ADEs had been in clinical use for more than 2 decades. Insulin, warfarin, and digoxin—drugs that have a narrow therapeutic index and require regular outpatient monitoring to prevent overdose or toxicity—accounted for about one third of ADEs in elderly persons treated in the ED and 41.5% of estimated hospitalizations. Insulin or warfarin was implicated in more than 25% of estimated hospitalizations. A recent 12-month study found that 25% to more than 50% of patients who were taking drugs with a narrow therapeutic range did not have serum concentration monitoring.2
Overall, the 5 drug classes most frequently associated with ADEs were insulins, opioid-containing analgesics, anticoagulants, amoxicillin-containing agents, and antihistamines/cold remedies. The most common ADEs were dermatologic, gastrointestinal, and neurologic.
INAPPROPRIATE USE AND UNDERUSE
In another new report, researchers found that inappropriate prescribing and underuse of appropriate medications are common among elderly persons.3 The study involved 196 outpatients aged 65 years or older who were taking 5 or more medications. One hundred twenty-eight patients (65%) were taking 1 or more inappropriate medications. This included 112 patients (57%) who were taking a total of 171 medications that were ineffective, not indicated, or therapeutically redundant and 73 patients (37%) who were taking a total of 91 agents that were classified as potentially inappropriate according to the Beers criteria.
The researchers also found that patients had taken 38 medications whose use in elderly persons is never recommended and 28 medications that were contraindicated in the presence of certain disorders; there were 25 violations of dosing criteria, drug-drug interactions, or combinations of problems. Of the 91 medication problems, 62 were classified as highly severe. Over-the-counter agents accounted for 22 (10%) of inappropriate drugs; about half of these were sedating antihistamines. The most common inappropriate drugs are listed in the Table.
Underuse was found in 125 patients (64%), for whom 199 agents considered useful and appropriate had not been prescribed. The most common underprescribed agents were cardiovascular medications, including antihypertensives, anticoagulants, and lipid-lowering drugs. Medications commonly omitted also included those for the prevention or treatment of GI conditions, diabetes, osteoporosis, and obstructive pulmonary disease.
The authors found that 82 patients (42%) were taking an inappropriate medication and simultaneously not taking one from which they might have benefited. Only 25 patients (13%) were receiving the correct balance of medications.
The use of inappropriate medications rose as the number of medications taken increased. Patients who took 5 or 6 medications used a mean of 0.4 inappropriate drugs, whereas those who took 7 to 9 agents used a mean of 1.1 inappropriate drugs and those who took 10 or more medications used a mean of 1.9 inappropriate drugs.
Underuse of medications averaged 1 underused drug per patient. Patients who were taking fewer than 8 medications were more likely to be missing a useful medication than to be taking an inappropriate one; the converse was true in patients taking more than 8 medications.
The authors note that the results of this study are consistent with previous reports that have found associations between polypharmacy and such undesirable outcomes as a higher likelihood of ADEs and higher rates of hospitalization and death.
1. Budnitz DS, Pollock DA, Weidenbach KN, et al. National surveillance of emergency department visits for outpatient adverse drug events. JAMA. 2006;296:1858-1866.
2. Raebel MA, Carroll NM, Andrade SE, et al. Monitoring of drugs with a narrow therapeutic range in ambulatory care. Am J Manag Care. 2006;12: 268-274.
3. Steinman MA, Landefeld CS, Rosenthal GE, et al. Polypharmacy and prescribing quality in older people. J Am Geriatr Soc. 2006;54: 1516-1523.