Natural history and mortality of chronic epilepsy in an untreated population of rural Bolivia: a follow-up after 10 years.

PURPOSE: To evaluate the natural history and mortality of chronic epilepsy in an untreated prevalence cohort of people with epilepsy (PWE) in a rural area of Bolivia. METHODS: During 1994-1996 we carried out an epidemiologic survey in a sample of 9,995 subjects in the Cordillera province. At the end of the survey we identified 130 PWE, of whom 118 were classified as having "active epilepsy." We revisited this cohort 10 years after the prevalence survey. RESULTS: We were able to trace 103 (87.3%) of the 118 PWE previously identified. Ten of the 103 subjects died during the follow-up period. Of the 93 PWE still alive, adequate information on the occurrence of seizures was available for 71 subjects, of whom 31 (43.7%) were seizure-free for more than 5 years; only 3 of these 31 subjects have taken an antiepileptic drug (AED) for more than 1 year. Generalized seizures were associated with a better prognosis. Mortality rate in our prevalent cohort was 10.0/1,000 person-year at risk [95% confidence interval (CI) 5.5-18.3], without a significant increased risk respect to the general population [standardized mortality rate (SMR) 1.34; 95% CI 0.68-2.39]; a significant increased risk of death was found for patients with remote symptomatic epilepsy (SMR 3.0; 95% CI 1.2-6.3) but not with idiopathic epilepsy. Three of the 10 subjects died of causes possibly related to epilepsy. DISCUSSION: Our data suggest that spontaneous remission of epilepsy occurs in a substantial proportion of untreated patients affected by chronic epilepsy; concerning mortality, we found a 3-fold increased mortality in patients with remote symptomatic epilepsy.