Epidemiology of Epilepsy in Low- and Middle-Income Countries: Experience of a Standardized Questionnaire over the Past Two Decades

Introduction: Epilepsy affects >50 million people worldwide, with 80% of them living in low- and middle-income countries (LMICs). Studies with a standardized methodology are required to obtain comparable data on epilepsy and implement health policies in order to reduce the treatment gap and improve the diagnosis and management of epilepsy. In 2000, following the guidelines of the International League Against Epilepsy (ILAE), the “questionnaire for investigation of epilepsy in tropical countries” (IENT questionnaire) was developed to promote epidemiological surveys on epilepsy using a standard methodology. This study aims to describe how, when, where, and why the IENT questionnaire has been used through epidemiological studies on epilepsy over the last 2 decades and to acquire users’ opinions about the tool. Methods: Studies that used the IENT questionnaire were searched through international and local bibliographic databases, including the gray literature. An online survey was carried out, including a snowball effect. Original research studies were included. Characteristics of the studies and populations and general information on the instrument and its use were collected. Results: Eighty-two documents were selected referring to 61 studies that were mostly carried out on the African continent (n = 54). Most of them aimed to determine the prevalence (n = 31) and associated factors (n = 28) of epilepsy in LMICs. Among the 61 studies, 35 were population-based, and 30 included both adults and children. A methodological heterogeneity was found between studies, and in cases where the IENT questionnaire alone did not ensure complete data collection, other tools were used concomitantly (n = 40). Discussion/Conclusion: Over the last 2 decades, the IENT questionnaire has been continuously used in different LMICs. This result favors its promotion and updating, with the inclusion of new topics related to epilepsy (e.g., comorbidities, quality of life, and stigma), current ILAE guidelines, and digital versions.