A population-based study of active and drug-resistant epilepsies in Northern Italy.

Drug-resistant epilepsy (DRE) is defined by the International League Against Epilepsy as a failure of adequate trials of two tolerated, appropriately chosen, and used antiepileptic drugs to achieve sustained seizure freedom. Our aim was to calculate the following: (1) the prevalence of active epilepsy and DRE in a well-defined population of Northern Italy and (2) the proportion of incident cases developing DRE. The study population (146,506; year 2008) resided in the province of Lecco, Northern Italy. The medical records of 123 general practitioners were reviewed to identify patients with epilepsy, diagnosed by a neurologist during the period 2000-2008. The point prevalence of active epilepsy and DRE was calculated on December 31, 2008. A total of 747 prevalent patients with epilepsy, 684 patients with active epilepsy, and 342 incident cases were identified. The frequency of DRE was 15.6% (107/684) of all active epilepsies and 10.5% (36/342) of incident cases. The point prevalence was 0.73 per 1000. The standardized prevalence of DRE was 0.7 per 1000 (Italian population) and 0.8 per 1000 (world population). Our data indicate that 1/6 patients with active epilepsy in the general population has DRE, and 1/10 patients with newly diagnosed epilepsy will develop DRE within nine years from the diagnosis.