The association between heatwaves and risk of hospitalization in Brazil: A nationwide time series study between 2000 and 2015

Abstract

Background To our knowledge, no study has assessed the association between heatwaves and risk of hospitalization and how it may change over time in Brazil. We quantified the heatwave–hospitalization association in Brazil during 2000–2015. Methods and findings Daily data on hospitalization and temperature were collected from 1,814 cities (>78% of the national population) in the hottest five consecutive months during 2000–2015. Twelve types of heatwaves were defined with daily mean temperatures of ≥90th, 92.5th, 95th, or 97.5th percentiles of year-round temperature and durations of ≥2, 3, or 4 consecutive days. The city-specific association was estimated using a quasi-Poisson regression with constrained distributed lag model and then pooled at the national level using random-effect meta-analysis. Stratified analyses were performed by five regions, sex, 10 age groups, and nine cause categories. The temporal change in the heatwave–hospitalization association was assessed using a time-varying constrained distributed lag model. Of the 58,400,682 hospitalizations (59% women), 24%, 34%, 21%, and 19% of cases were aged <20, 20–39, 40–59, and ≥60 years, respectively. The city-specific year-round daily mean temperatures were 23.5 ± 2.8 °C on average, varying from 26.8 ± 1.8 °C for the 90th percentile to 28.0 ± 1.6 °C for the 97.5th percentile. We observed that the risk of hospitalization was most pronounced for heatwaves characterized by high daily temperatures and long durations across Brazil, except for the minimal association in the north (the hottest region). After controlling for temperature, the association remained for severe heatwaves in the south and southeast (cold regions). Children 0–9 years, the elderly ≥70 years, and admissions for perinatal conditions were most strongly associated with heatwaves. Over the study period, the strength of the heatwave–hospitalization association declined substantially in the south, while an apparent increase was observed in the southeast. The main limitations of this study included the lack of data on individual temperature exposure and measured air pollution. Conclusions There are geographic, demographic, cause-specific, and temporal variations in the heatwave–hospitalization associations across the Brazilian population. Considering the projected increase in frequency, duration, and intensity of heatwaves, future strategies should be developed, such as building early warning systems, to reduce the health risk associated with heatwaves in Brazil.

Association between Weather Types based on the Spatial Synoptic Classification and All-Cause Mortality in Sweden, 1991–2014

“…This effect refers to a decrease in the expected number of deaths after a harmful (e.g., heat) event when a significant number of critically ill people die that would have died shortly afterwards anyway [44]. Mortality displacement has been reported in several previous studies from several geographical areas such as Brazil [45], China [46], the United States [47], and several European countries [48]. In our northern locations, despite the high mortality at lag 0 associated with DT in summer, the cumulative effect at day 14 was not significant, possibly due to mortality displacement at lags 10–11.…”

Global and cross-country analysis of exposure of vulnerable populations to heatwaves from 1980 to 2018

“…Studies have considered the health impacts of past heatwaves by comparing health outcomes from heatwave events with local or global heatwave indexes. In general, this has been performed for a selection of cities or regions (Anderson and Bell 2009;Campbell et al 2018;Li et al 2015;Russo et al 2015;Scalley et al 2015;Zhao et al 2019Zhao et al , 2018 or by collecting many individual studies (Mora et al 2017). Guo et al (2018Guo et al ( , 2017 combined mortality and climate data to estimate heatwave impacts for 412 communities in 20 regions.…”

Ambient temperature and mortality due to acute myocardial infarction in Brazil: an ecological study of time-series analyses

“…Besides, the number of daily deaths in Manaus is small and, consequently, the statistical power is lower. In addition, another recent study showed an association between heat exposure and increased risk of all-causes hospitalizations in all Brazilian regions, but not for cardiovascular hospitalizations 45,46 .…”