Effects of extreme temperatures on cerebrovascular mortality in Lisbon: a distributed lag non-linear model
Cerebrovascular diseases are the leading cause of mortality in Portugal, especially when related with extreme temperatures. This study highlights the impacts of the exposure-response relationship or lagged effect of low and high temperatures on cerebrovascular mortality, which can be important to reduce the health burden from cerebrovascular diseases. The purpose of this study was to assess the effects of weather on cerebrovascular mortality, measured by ambient temperature in the District of Lisbon, Portugal. A quasi-Poisson generalized additive model combined with a distributed lag non-linear model was applied to estimate the delayed effects of temperature on cerebrovascular mortality up to 30 days. With reference to minimum mortality temperature threshold of 22 °C, there was a severe risk (RR = 2.09, 95% CI 1.74, 2.51) of mortality for a 30-day-cumulative exposure to extreme cold temperatures of 7.3 °C (1st percentile). Similarly, the cumulative effect of a 30-day exposure to an extreme hot temperature of 30 °C (99th percentile) was 52% (RR = 1.65, 95% CI 1.37, 1.98) higher than same-day exposure. Over the 13 years of study, non-linear effects of temperature on mortality were identified, and the probability of dying from cerebrovascular disease in Lisbon was 7% higher in the winter than in the summer. The findings of this study provide a baseline for future public health prevention programs on weather-related mortality.
KeywordsCerebrovascular diseases Extreme temperatures Lag effects Distributed lag non-linear model (DLNM) Portugal
The authors would like to thank the Portuguese National Statistics Institute – Statistics Portugal for its support with obtaining the health data from this database. Mónica Rodrigues and Paula Santana are members of CEGOT, Research Centre on Geography and Spatial Planning, that is supported by the European Regional Development Funds, through the COMPETE 2020 – Operational Programme ‘Competitiveness and Internationalization’, under Grant POCI-01-0145- FEDER-006891; and by National Funds through the Portuguese Foundation for Science and Technology (FCT) under Grant UID/GEO/04084/2013. The funders had no role in study design, data collection, data analysis, data interpretation, or writing of the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
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