The Role of Thermal Stress on CHF Admissions in a Tropical Climate

Abstract

Objectives:A previous study of emergency department visits for Congestive Heart Failure (CHF) to hospitals in New Jersey revealed a marked increase in the colder months. This was attributed in part to increased demands on the heart in response to cold weather. We speculated that the extreme high temperatures in the tropics would place a similar additional burden on the heart. Therefore, we hypothesized an increase in the number of hospital admissions for CHF during the warmest months in the tropics. Methods:Design: Retrospective cohort.Setting: Community hospital in Chennai, Southern India. Participants: All patients ages 15 and older admitted to the hospital fromProtocol: We examined all hospital inpatient discharge diagnoses and selected those for CHF. We analyzed the data by month, testing for statistical significance using Chi Square and Student's t tests with alpha set at 0.05. Results:Of the 6,800 total hospital medical admissions, there were 513 admissions for CHF. Of the CHF visits, 46% were female and the average age was 66 ± 12 years. The four coldest months (average temperature=29°C) had 1.46 (95% CI 1.12-1.79, p=0.015) times more visits than the four warmest months (average temperature=37°C). Conclusion:Contrary to our hypothesis, we found a statistically significant decrease in CHF visits in the warmer months. We speculate that the additional burden imposed by thermal stress on the heart may be more than offset by the vasodilatory effect of high ambient temperatures.