Extreme precipitation and hospital admissions for gastrointestinal illness in Chennai, India

Background: The increased frequency, intensity, and duration of extreme weather events associated with climate change is expected to exaggerate global health disparities. This study evaluated the association between extreme precipitation and hospital admissions in Chennai, India. Methods: Daily hospital admission data from two government hospitals in Chennai were merged with daily meteorological data from Chennai International Airport for 2004-2007. Poisson regression models were fit to evaluate the association between extreme precipitation (≥90th percentile) and hospital admissions over a 15-day lag period, controlling for apparent temperature, day of week, and long-term time-trends. Season and age were explored as potential effect modifiers. Results: Extreme precipitation was consistently associated with hospital admissions due to gastrointestinal illness (GI). The risk of being hospitalized due to GI following a 15-day period of extreme precipitation, among all ages, was 1.61 (95% confidence interval (CI): 1.29, 2.00). Among the young the risk estimate was 2.65 (95% CI: 1.21, 5.80) and among the old the risk estimate was 1.68 (95% CI: 1.01, 2.80). Risk also varied across seasons, with the strongest association between hospital admissions and extreme precipitation during the pre-monsoon period (March-May). Conclusions: Extreme precipitation was associated with GI-related hospital admissions in Chennai, India, with elevated risks among the young and old. Given the predicted increase in extreme weather events and increased weather variability, populations in India may be at an increased risk of waterborne disease.