A longitudinal study of epilepsy in Kolkata, India

Abstract

This study aimed to determine the prevalence, incidence, and mortality rates of epilepsy in the city of Kolkata, India. This is the first such longitudinal study in a heterogeneous urban Indian population. A two-stage door-to-door survey of a stratified random sample was undertaken within the municipal limits of Kolkata. Trained field workers detected and interviewed the cases using a simple screening questionnaire, and the detailed follow-up was done by neurologists. The survey was conducted annually for five consecutive years from March 2003 through February 2008. A total of 52,377 (52.74% men) individuals were screened. There were 309 prevalent and 66 incident cases of active epilepsy. The prevalence and average annual incidence rate (AAIR) with 95% confidence interval (CI), age-standardized to World Standard Population, were 572.8 (509.79-641.54) per 100,000 and 27.27 (21.03-34.80) per 100,000 per year, respectively. The age-specific incidence rates of epilepsy showed bimodal distribution. During the 5-year period, 20 cases of active epilepsy died. The average annual mortality rate (AAMR) was 7.63 (95% CI 4.45-11.26) per 100,000 population per year. Compared to the general population of Kolkata, the all-cause standardized mortality ratio (SMR) for persons with epilepsy was 2.58 overall (men 3.67; women 1.77). There was no significant difference between slum and nonslum dwellers in epidemiologic parameters. The AAIR of epilepsy is comparable to that observed in developed countries, but AAMR is higher. The all-cause SMR for epilepsy relative to the general population is, however, similar to that of developed nations.