A longitudinal study of epilepsy in Kolkata, India

P>Purpose: 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. Methods: 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. Results: 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. Conclusions: 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.