Antiepileptic Drugs and Accumulation of Hospital Days Among Persons With Alzheimer's Disease

Objectives: To compare the accumulation of hospital days between initiators and noninitiators of anti-epileptic drugs (AEDs) among persons with Alzheimer's disease (AD). Design: Exposure-matched cohort study. Setting and participants: Persons newly diagnosed with AD in 2005-2011 (n = 70,718) and initiating AED use identified from Finnish health care registers. For each AED initiator, 1 noninitiator matched on age, sex, and time since AD diagnosis was selected. Persons with epilepsy were excluded from the study. Methods: Association between AED initiation or use of individual AEDs and accumulation of hospital days during a 2-year follow-up was assessed using negative binomial model. Results: AED initiators (n = 4432) were hospitalized on average for 43.7 (SD: 88.3) days and matched noninitiators for 32.2 (SD: 71.3) days during the 2-year follow-up. Altogether, 27.3% of the AED initiators and 35.6% of the noninitiators had no hospital days during the study period. Number of accumulated hospital days during the follow-up was 31% higher [adjusted incidence rate ratio (aIRR): 1.31, 95% confidence interval (CI): 1.19-1.43] among AED initiators than the noninitiators. Hospital days due to diseases of the nervous system excluding dementia (aIRR: 2.72, 95% CI: 1.72-4.31), musculoskeletal system (aIRR: 2.49, 95% CI: 1.73-3.58), respiratory system (aIRR: 1.89, 95% CI: 1.47-2.43), and mental and behavioral disorders excluding dementia (aIRR: 1.96, 95% CI: 1.02-3.79) were more common among the AED initiators than noninitiators. Among pregabalin (aIRR: 0.65, 95% CI: 0.56-0.77), gabapentin (aIRR: 0.66, 95% CI: 0.49-0.88), and clonazepam (aIRR: 0.73, 95% CI: 0.55-0.96) initiators, the number of accumulated hospital days was 27% to 35% lower than the days accumulated among the initiators of valproic acid. Conclusions and implications: AED initiators had more hospital days than noninitiators. Pregabalin and gabapentin were associated with a lower number of hospital days than valproic acid. Further research is needed on the reasons for these findings. (C) 2018 The Author(s). Published by Elsevier Inc. on behalf of AMDA - The Society for Post-Acute and Long-Term Care Medicine. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).