Association between apparent temperature and cardiovascular disease hospital admissions in Cape Town, South Africa

Abstract

PDS 72: Environmental health issues in LMIC, Exhibition Hall (PDS), Ground floor, August 28, 2019, 10:30 AM - 12:00 PM Background: Studies globally reported on health effects due to cold and heat, but research from developing countries and Africa is limited. Methods: Cardiovascular disease (CVD) admission data (ICD10: I00-I99) were obtained from seven private hospitals in Cape Town, South Africa for 1 January 2011 to 31 October 2016. NO2, SO2, PM10, temperature and relative humidity data were obtained from the City of Cape Town and South African Weather Services. Quasi-Poisson regression models with a distributed lag non-linear model component were applied. A 21-day lag period for Tapp was investigated. Models were adjusted for confounders. Susceptibility by sex and age groups (15–64 years and ≥65 years) was explored. Results: Of the 54 818 CVD admissions, 42% and 58% females and males were admitted, respectively. Approximately equal number of admissions were from 15-64 and ≥65 year olds. The mean Tapp was 16.3 °C. The highest PM10 level was 84.7 μg.m-3. SO2 and NO2 varied between 0.7-45.8 μg.m-3 and 1.4-67.3 μg.m-3, respectively. PM10 and SO2 levels exceeded the daily World Health Organization guidelines of 50 µg.m-3 and 20 µg.m-3 on 90 and 56 days, respectively. Cold and heat effects were observed. The cumulative RR over the 21-day lag period for all ages and both sexes was 0.81 95% 0.67-0.97 per °C increase from the 5th percentile (10°C) to the median Tapp (16°C). Females seem to be more susceptible to both cold and heat effects. The elderly seemed to be more susceptible to heat than cold effects: 0.69 95% 0.55-0.85 per °C increase from the median Tapp (16°C) to the 95th percentile (23°C). Conclusions: The results can be used in present-day early warning systems and in risk assessments to estimate the impact of cold and heat in Cape Town. Future research should expand to the other major cities in the country.