New-onset Epilepsy Risk Factors in Older Veterans

Objectives: To identify risk factors for new-onset geriatric epilepsy that may trigger clinicians to consider a differential diagnosis of epilepsy at symptom onset.

Design: Retrospective cohort study.

Setting: National Veterans Affairs (VA) databases.

Participants: Veterans aged 66 and older in fiscal year 2000 (FY00) who received VA care in FY99 and FY00. Individuals with new-onset epilepsy based on a validated algorithm constituted the epilepsy cohort (n=1,843), and individuals without epilepsy constituted the geriatric cohort (n=1,023,376).

Measurements: Age, sex, and race were derived from VA databases. Clinical conditions associated with new-onset geriatric epilepsy (e.g., cerebrovascular disease, dementia, brain tumor) and stroke risk-factors (e.g., hypertension, diabetes mellitus, cardiovascular disease) were identified using validated International Classification of Diseases, Ninth Revision, Clinical Modification, codes before epilepsy onset (epilepsy cohort) and in FY00 (geriatric cohort).

Results: Multivariable logistic regression analysis indicated that patients with cerebrovascular disease (odds ratio (OR)=3.50, 95% confidence interval (CI)=3.13-3.91), cerebrovascular disease and dementia (OR=4.14, 95% CI=3.46-4.96), brain tumor (OR=2.14, 95% CI=1.46-3.13), head injury (OR=2.11, 95% CI=1.41-3.14), and other central nervous system (CNS) conditions (OR=1.57, 95% CI=1.32-1.88) were more likely to experience new-onset epilepsy. Statin prescription (OR=0.64, 95% CI=0.56-0.73), older age (> or =85 vs 66-74, OR=0.66, 95% CI=0.50-0.87), obesity (OR=0.74, 95% CI=0.62-0.87), and hypercholesterolemia (OR=0.87, 95% CI=0.76-0.98) were associated with a lower likelihood of epilepsy.

Conclusion: These data suggest greater epilepsy risk for older individuals with CNS insult and an additive effect of cerebrovascular disease and dementia. The statin finding requires further exploration but points to a possible target for prevention of geriatric epilepsy.