Prevalence of appropriate and problematic antiepileptic combination therapy in older people in the nursing home

OBJECTIVES: To determine the prevalence of mono- and poly-antiepileptic drug (AED) therapy in a cohort of nursing home (NH) residents and to describe specific AED combinations used, as well as demographic, clinical, and functional factors associated with poly-AED therapy and the most common AED combination. DESIGN: Retrospective, point prevalence study. SETTING: All NHs owned/managed by Beverly Enterprises. PARTICIPANTS: All residents aged 65 and older residing in one of the study NHs on July 1, 1999, and receiving an AED (N = 3,881). MEASUREMENTS: Data were gathered using two secondary source data sets: physicians' orders (AED use) and the Minimum Data Set (health status indicators). RESULTS: Of residents taking AEDs, 370 (9.5%) were taking two or more; 268 of those (72%) were taking problematic AED combinations (those with the potential of undesirable pharmacokinetic or pharmacodynamic interactions). Phenytoin (PHT) with phenobarbital (PB) was the most common combination (27.0%). Logistic regression indicated that poly-AED subjects were more likely to have a diagnosis of epilepsy/seizure (epi/sz) and less likely to have a diagnosis of cerebrovascular accident (CVA). Residents taking the PHT/PB combination were more likely to have an epi/sz diagnosis and longer NH stay. The association between CVA and PHT/PB polytherapy differed by presence or absence of aphasia. CONCLUSION: The overall prevalence of poly-AED therapy is less than 10% in NH residents, but 72% of those residents were receiving problematic polytherapy combinations, thereby exposing them to potential risk of adverse reactions and toxicity.