Use of Antiepileptic Medications In Nursing Homes

The University of Minnesota Epilepsy Research and Education Program published two studies evaluating the use of antiepileptic drugs (AEDs) among nursing home (NH) elderly. The studies used a large, nongovernmental data set for studying this population. This chapter is a summary of those two studies. In the first study, a 1‐day point prevalence study, 10.5% of the NH residents had one or more AED orders, a prevalence 10 times greater than that found in the community. In a multivariate analysis of factors associated with AED treatment, seizure indication was the most important factor, and age was inversely related to AED use. Phenytoin was the most commonly used AED, followed by carbamazepine, phenobarbital, and valproic acid. The most frequently used combination was phenytoin and phenobarbital. In the second study, evaluating NH admission data, 8% of newly admitted residents were already receiving one or more AEDs when they entered the NH. Factors associated with AED use in this group included epilepsy/seizure disorder, age, cognitive performance, and manic depression (bipolar disease). Among residents recently admitted who were not using an AED at entry, 3% were initiated on an AED within 3 months of admission. Among the factors associated with the initiation of AEDs during this period, the strongest association was with epilepsy/seizure disorder. Manic depression (bipolar disease) was also significantly associated with initiation of an AED after admission. In this group, there was an inverse relationship between age and initiation of an AED.

Introduction

This chapter summarizes research that was conducted by the University of Minnesota Epilepsy Research and Education Program to evaluate the use of antiepileptic drugs (AEDs) by elderly people in nursing homes (NHs) (Garrard 2000, Garrard 2003). Epilepsy, defined as two or more unprovoked seizures, was described at the population level by Hauser and colleagues in a data set from Olmsted County in Minnesota during the period 1935–1984 (Hauser 1995, Hauser 1991, Hauser 1993, Hauser 1996). Their research concentrated on community‐dwelling people of all ages and demonstrated that the incidence of epilepsy in the population forms a U‐shaped curve over the life span, with one of the highest incidence rates during the first year of life, and even higher rates among the elderly, beginning at approximately 60 years of age and rising with increasing age. This finding of higher incidence among the elderly has been replicated in other populations, for example, a study of urban Danes >60 years of age (Luhdorf et al., 1986). The prevalence of epilepsy, that is, the proportion of existing cases of epilepsy in the population at a specified point in time, is estimated to range between 0.68% and approximately 1.5% of the population as a whole (Hauser 1992, Hauser 1991, Hauser 1996).

With the leading edge of the “baby boom” generation about to turn 65 years of age, the number of elderly in the US population is poised to soar, projected to increase from an estimated 40 million in 2010 to 71.5 million in 2030 (Administration on Aging, 2005). Given these statistics, the recognition and treatment of epilepsy among people 65 years and older is a concern of health practitioners and families alike.

As people age, their need for NH care increases due to greater frailty and disease. For patients aged 65 years and older, there is a lifetime risk of 43–46% of ever becoming a resident in an NH (Kemper 1991, Spillman 2002). At any one time, 4.5% of the elderly US population is residing in NHs (Hetzel and Smith, 2001).

Most existing research about epilepsy and its treatment focuses on people in the community who are below the age of 65; hence, there have been few large‐scale epidemiological studies of seizures in the older population. Even less is known about the epidemiology of the treatment of epilepsy in NH elderly. Whether AEDs are prescribed differently for particular subgroups of elderly patients, for example, by age, gender, sex, racial identity, or geographic location, is not known.

In any study of elderly people, it is important not to confuse those at one end of the age spectrum, at 65 years, with those in the older subgroups. For example, to equate “elderly” who are 65 years of age with those who are 85 years of age in terms of functional or cognitive abilities is just as erroneous as equating “teenagers” who are 13 years of age with those who are 19 years of age. Those ≥85 years of age are more likely to develop chronic illness, be disabled, and be more dependent on others for assistance with daily activities (US Department of Commerce, 1993). Despite this, age distinctions between elderly subgroups are frequently not made in research. Another set of subgroups that has become crucial to the study of pharmacoepidemiological research is that of race/ethnicity. In 2004, 18.1% of the elderly US population were members of a minority group. This figure is projected to increase to 23.6% by the year 2020 (Administration on Aging, 2005).

In any research concerning NHs, the distinction must also be made between residents and admissions. A resident cohort includes all residents in the facility at a specified time, which is usually a cross‐sectional sample. Such a sample consists of a mixture of newly admitted residents and others who have been in the NH for different periods. In contrast, an admission cohort includes all people admitted to a facility during a specified period. Studies of both cohorts are important in gerontological research on the treatment and outcomes of elderly people living in NHs (Coughlin 1990, Liu 1994). Because of current health care delivery practices, many patients needing temporary rehabilitation care are transferred to NHs, with the expectation by health care providers and the patients themselves that the NH stay will be temporary. Since Medicare reimburses active rehabilitation care up to the first 100 days (Liu et al., 1999) and federal regulations require that Medicare‐reimbursed rehabilitation patients be seen by a physician or nurse practitioner every 30 days (compared to once every 3 months for nonrehabilitation patients), an admissions cohort will have a larger proportion of residents under closer clinical scrutiny than will a cross‐sectional sample of residents. Both kinds of samples, resident and admission, are important in understanding diseases and their treatment, including epilepsy and AED use.

Until the publication by Garrard et al. (2000) on epilepsy/seizure disorder and AED use, no large‐scale pharmacoepidemiology studies about the use of antiseizure medications in NH elderly, comparable to Hauser's community‐based samples, had been reported in the literature. In this chapter, these NH study results are summarized, with a focus on AED use, regardless of the underlying condition being treated, although some analyses are stratified by the presence or absence of epilepsy/seizure disorder.

The first study (Garrard et al., 2000), which concentrated on the use of AEDs by people already living in the facilities (i.e., NH residents), discovered a considerable difference in AED prevalence between NH residents and community‐based elderly. These findings formed the basis for the next question: Do elderly people enter NHs with this level of AED use, or are they initiated on these drugs after admission? This question resulted in the second study (Garrard et al., 2003), which explored AED use at the time of NH admission and at a follow‐up 3 months after admission.

The results of both studies are summarized in this chapter in the context of the following three questions:

• What is the prevalence of AED use by NH residents, and what factors are associated with such use?

• What is the prevalence of AED use by elderly people on admission to the NH, and what factors distinguish between those with or without AED use at entry?

• Of newly admitted residents without AED use at NH entry, what percentage were initiated on AEDs within 3 months of admission, and what factors were associated with postadmission initiation of AEDs?