Economic impact of epilepsy and the cost of nonadherence to antiepileptic drugs in older Medicare beneficiaries.

Epilepsy is most prevalent among older individuals, and its economic impact is substantial. The development of economic burden estimates that account for known confounders, and using percent incremental costs may provide meaningful comparison across time and different health systems. The first objective of the current study was to estimate the percent incremental healthcare costs and the odds ratio (OR) for inpatient utilization for older Medicare beneficiaries with epilepsy and without epilepsy. The second objective was to estimate the percent incremental healthcare costs and the OR for inpatient utilization associated with antiepileptic drug (AED) nonadherence among Medicare beneficiaries with epilepsy. The OR of inpatient utilization for cases compared with controls (i.e., non-cases) were 2.4 (95% CI 2.3 to 2.6, p-value<0.0001) for prevalent epilepsy and 3.6 (95% CI 3.2 to 4.0, p-value<0.0001) for incident epilepsy. With respect to total health care costs, prevalent cases incurred 61.8% (95% CI 56.6 to 67.1%, p-value<0.0001) higher costs than controls while incident cases incurred 71.2% (95% CI 63.2 to 79.5%, p-value <0.0001) higher costs than controls. The nonadherence rates were 33.6 and 32.9% for prevalent and incident cases, respectively. Compared to nonadherent cases, the OR of inpatient utilization for adherent prevalent cases was 0.66 (95% CI 0.55 to 0.81, p-value <0.0001). The cost saving for a prevalent case adherent to AEDs was 13.2% (95% CI 6.6 to 19.4%, p-value=0.0001) compared to a nonadherent case. An incident case adherent to AEDs spent 16.4% (95% CI 6.5 to 25.2%, p-value=0.002) less than a nonadherent incident case on health care. Epilepsy is associated with higher health care costs and utilization. Older Medicare beneficiaries with epilepsy incur higher total health care spending and have higher inpatient utilization than those without epilepsy. Total health care spending is less for older Medicare beneficiaries who have prevalent or incident epilepsy if they are adherent to AEDs.