Temperature variability associations with cardiovascular and respiratory emergency department visits in Dhaka, Bangladesh.

Abstract

Greenhouse gas emissions are changing the Earth's climate, most directly by modifying temperatures and temperature variability (TV). Residents of low- and middle-income countries (LMICs) are likely more adversely affected, due to lack of air conditioning to compensate. To date, there is no local epidemiological evidence documenting the cardio-respiratory health effects of TV in Dhaka, Bangladesh, one of the most climate change vulnerable cities in the world. We assessed short-term TV associations with daily cardiovascular disease (CVD) and respiratory emergency department (ED) visits, as well as effect modification by age and season. TV was calculated from the standard deviations of the daily minimum and maximum temperatures over exposure days. Time-series regression modeling was applied to daily ED visits for respiratory and CVD from January 2014 through December 2017. TV effect sizes were estimated after controlling for long-term trends and seasonality, day-of-week, holidays, and daily mean relative humidity and ambient temperature. A 1°C increase in TV was associated with a 1.00% (95%CI: 0.05%, 1.96%) increase in CVD ED visits at lag 0-1days (TV0-1) and a 2.77% (95%CI: 0.24%, 5.20%) increase in respiratory ED visits at lag 0-7days (TV0-7). TV-CVD associations were larger in the monsoon and cold seasons. Respiratory ED visit associations varied by age, with older adults more affected by the TV across all seasons. A 1°C increase in TV at lag 0-7days (TV0-7) was associated with a 7.45% (95%CI: 2.33%, 12.57%) increase in respiratory ED visits among patients above 50years of age. This study provided novel and important evidence that cardio-pulmonary health in Dhaka is adversely affected year-round by day-to-day increases in TV, especially among older adults. TV is a key factor that should be considered in evaluating the potential human health impacts of climate change induced temperature changes.