The Prevalence and Factors Associated with Antiepileptic Drug Use in US Nursing Home Residents

Background Antiepileptic drugs (AEDs) are commonly used by nursing home residents, both on- and off-label. The landscape of AED use has changed over the past two decades; however, despite this, contemporaneous research on AED use in US nursing home residents is scant. Objective The aim of this study was to estimate the prevalence of AED use, describe prescribing patterns, identify factors associated with AED use, and assess whether these factors differ among AEDs with expanded indications in older adults (i.e. gabapentin, pregabalin, topiramate, and lamotrigine). Methods We conducted a cross-sectional study among 549,240 long-stay older residents who enrolled in fee-for-service Medicare and lived in 15,111 US nursing homes on 1 September 2016. Demographics and conditions associated with AED indications, epilepsy comorbidities, and safety data came from the Minimum Data Set Version 3.0 (MDS 3.0). Medicare Part D claims were used to identify AED use. Robust Poisson models and multinomial logistic models for clustered data estimated adjusted prevalence ratios (aPR), adjusted odds ratios (aOR), and 95% confidence intervals (CIs). Results Overall, 24.0% used AEDs (gabapentin [13.3%], levetiracetam [4.7%], phenytoin [1.9%], pregabalin [1.8%], and lamotrigine [1.2%]). AED use was associated with epilepsy (aPR 3.73, 95% CI 3.69-3.77), bipolar disorder (aPR 1.20, 95% CI 1.18-1.22), pain (aPR(moderate/severe vs. no pain) 1.42, 95% CI 1.40-1.44), diabetes (aPR 1.27, 95% CI 1.26-1.28), anxiety (aPR 1.12, 95% CI 1.11-1.13), depression (aPR 1.17, 95% CI 1.15-1.18), or stroke (aPR 1.08, 95% CI 1.06-1.09). Residents with advancing age (aPR(85+ vs. 65-74 years) 0.73, 95% CI 0.73-0.74), Alzheimer's disease/dementia (aPR 0.87, 95% CI 0.86-0.88), or cognitive impairment (aPR(severe vs. no impairment) 0.62, 95% CI 0.61-0.63) had decreased AED use. Gabapentinoid use was highly associated with pain (aOR(moderate/severe vs. no pain) 2.07, 95% CI 2.01-2.12) and diabetes (aOR 1.79, 95% CI 1.76-1.82), but not with an epilepsy indication. Conclusions AED use was common in nursing homes, with gabapentin most commonly used (presumably for pain). That multiple comorbidities were associated with AED use underscores the need for future studies to investigate the safety and effectiveness of AED use in nursing home residents.