February 24, 2011

Emergency Department Visits Involving Adverse Reactions to Medications among Older Adults

As adults age, they experience increased health problems, have more medical visits, and take an increasing number of medications (pharmaceuticals and over-the-counter [OTC] medications) compared with younger persons.^1,2 Because of physiological changes (e.g., decreased kidney and liver function) and because adults aged 50 or older (hereafter referred to as older adults) often take multiple medications, they are at higher risk of experiencing an adverse reaction to drugs than younger persons.^1,2 These increased risks represent a public health problem because the aging population is projected to increase in the next several decades.³

The Drug Abuse Warning Network (DAWN) is a public health surveillance system that monitors drug-related emergency department (ED) visits in the United States.⁴ To be a DAWN case, the ED visit must have involved a drug, either as the direct cause of the visit or as a contributing factor. Within DAWN, ED visits involving an adverse reaction fall into the category of visits in which a prescription or over-the-counter pharmaceutical was taken for therapeutic purposes and was used as prescribed or directed but caused adverse drug reactions, side effects, drug-drug interactions, or drug-alcohol interactions. Because DAWN data include drug-related ED visits involving adverse reactions to pharmaceuticals, these national data can provide valuable information about adverse reactions serious enough to warrant emergency care.⁵ This issue of The DAWN Report focuses on ED visits that involve adverse reactions to medications among older adults in 2008.⁶

In 2008, an estimated 2,157,128 ED visits were made by patients for adverse reactions to pharmaceuticals or other types of medications. Older adults accounted for more than half (51.5 percent, or 1,111,686 visits) of all visits involving adverse reactions.

Among older adults, more than half of these visits (61.5 percent) were made by patients aged 65 or older (Table 1). Females accounted for 60.9 percent of the ED visits for adverse reactions to medications among older adults.

Of all ED visits involving adverse reactions among older adults, the majority involved pharmaceuticals only (98.9 percent), whereas a small percentage (1.1 percent) involved a combination of alcohol and pharmaceuticals. There were no differences by age group.

Nearly 8 in 10 visits (79.5 percent, or 873,975 visits) involved only one pharmaceutical, almost 1 in 7 visits (13.7 percent, or 151,009 visits) involved two pharmaceuticals, and less than 1 in 10 (6.8 percent, or 74,904 visits) involved three or more pharmaceuticals (Figure 1).

Figure 1. Number of Pharmaceuticals Involved in Emergency Department (ED) Visits for Adverse Reactions among Adults 50 or Older: 2008

Central nervous system (CNS) drugs (e.g., pain relievers and drugs used to treat anxiety and insomnia) were involved in almost one fourth (24.3 percent) of ED visits for adverse drug reactions among older adults (Table 2). The most commonly involved CNS drugs most commonly involved in visits for adults aged 50 to 64 were narcotic pain relievers (9.7 percent). Less than 1 in 10 visits among adults aged 65 or older involved narcotic pain relievers (8.3 percent) and non-narcotic pain relievers (8.7 percent).

After CNS drugs, the medications most often involved in ED visits for adverse reactions varied by age group. For those aged 50 to 64, anti-infection medications were the second most commonly involved type of medications in these visits, followed by cardiovascular system medications and drugs for metabolic disorders. For those aged 65 or older, blood modifiers were the second most commonly involved type of medications, followed by cardiovascular system medications and anti-infection medications.

Nearly two thirds of older adults who visited the ED for adverse drug reactions were treated and released (64.2 percent, or 714,099 visits) and nearly one third were admitted to the hospital (32.9 percent, or 365,993 visits) (Figure 2). Considerable variation was noted between the two age groups, with patients aged 50 to 64 being admitted to the hospital at a lower percentage than those aged 65 or older (25.5 vs. 37.6 percent, respectively). Less than 4 percent of both age groups were admitted to the intensive care unit (3.5 percent for patients aged 50 to 64 and 3.4 percent for patients aged 65 or older).

Figure 2. Disposition of Emergency Department (ED) Visits for Adverse Reactions to Medications among Older Adults, by Age Group: 2008

Of the older adults experiencing an adverse reaction that resulted in a hospital admission, more than 3 in 4 visits (76.9 percent, or 281,448 visits) involved one medication, less than 1 in 6 visits (14.5 percent, or 53,104 visits) involved two medications, and less than 1 in 10 visits (8.6 percent, or 31,440 visits) involved three or more medications. Blood modifiers (24.3 percent), CNS drugs (22.4 percent), and cardiovascular system medications (18.3 percent) were the drugs most commonly involved in visits that resulted in hospital admissions.

ED visits and hospital admissions related to adverse reactions among older adults are common and place a costly burden on health care services. The demand for such services will increase as the United States population ages, in general, and when the "baby boom" generation reaches older adulthood in particular. This report shows that the majority of visits involving adverse reactions among older adults involved only one pharmaceutical. Moreover, of the nearly one third (32.9 percent) of visits that resulted in a hospital admission among this population, 76.9 percent involved only one medication as well.

These findings underscore the critical importance for continued surveillance of adverse reactions to maintain drug safety. Enhancing drug safety is an important step toward increasing medical care quality and reducing health care costs overall. Although most adverse reactions involve a sungle drug, patients can help prevent drug-drug interactions by informing physicians, nurses, and mental health care providers of all medications, supplements, and vitamins they take and making sure that any medical records are shared with all physicians, including specialists. Patients can safeguard against adverse reactions by using one pharmacy to handle all their prescriptions and by advising their pharmacy of any adverse reactions to prescription or OTC medications.⁷

As parents age, family members and other care providers may have increasing responsibility to monitor the drugs taken by older adults. Caregivers need to be knowledgeable about the potential side effects of both prescription and over-the-counter medications and be aware of any past history of adverse reactions to particular pharmaceuticals and medications.