Epidemiology of goitres in Sri Lanka with Geographic Information System Mapping: a population based cross sectional study

Abstract

BACKGROUND: Sri Lanka is considered an endemic region for goiter. Early researchers have suggested the existence of a goiter belt based on rainfall pattern. Subsequent studies done in school children have challenged this theory. Current study is a community-based cross-sectional study done to assess the epidemiology of goiters. Geographic information system (GIS) mapping of the goiter prevalence is developed for the first time in Sri Lanka. METHODS: Study subjects were selected using a multi-staged cluster sampling with probability proportionate to size (PPS) method. Examination for the presence of goiters was done by two trained investigators and graded. ArcGIS 10 software was used for geostatistical analysis and developing a map by interpolating the data collected for the first time in Sri Lanka. RESULTS: A total of 5200 individuals (female-66%, median age-38 years; range 10-92 years) were assessed and 426 goiters were detected. The adjusted prevalence rate of goiters was 6.8%. Kriging interpolation method was used to develop the most appropriate epidemiological map clustering of high prevalence areas with scattered pockets of high prevalence was observed. Current map does not show a prevalence pattern in relation to the rainfall or elevation above sea level as proposed in the past. CONCLUSION: Goiter prevalence in Sri Lanka appears to be different from earlier proposed patterns. Use of GIS has contributed to develop a comprehensive epidemiological map of goiters demonstrating the absence of an endemic goiter belt in the wet zone as proposed earlier.