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Abstracts of the 2019 Annual Conference of the International Society for Environmental Epidemiology, August 25-28 2019, Utrecht, the Netherlands

Geographical variability of the minimum mortality temperature: A multi-country analysis

A, Tobias1; M, Hashizume2; C, Ng2; T, Dang3; Y, Honda4; F, Sera5; B, Armstrong5; A, Gasparrini5

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doi: 10.1097/01.EE9.0000610428.83272.8b
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OPS 13: Heat, cold and mortality, Room 117, Floor 1, August 26, 2019, 1:30 PM - 3:00 PM

Background/Aim: The temperature-mortality relationship has been described as a J- or U-shaped with a temperature at which risk of mortality is at the minimum (MMT). Little is known about the geographical variation of the MMT worldwide and the underlying factors that could explain adaptation to climate. We aim to investigate the determinants of the geographical variation in the MMTs according to climatic zones.

Methods: We collected data from 564 locations in 33 countries between 1985 and 2015. We applied a two-stage time-series design. First, for each location, we modelled mortality-temperature associations across 21 days of lag using quasi-Poisson regression and distributed lag nonlinear models to derive the city-specific MMT and its standard error. Second, we used random-effects meta-analysis to summarize the MMTs distribution by country, geographical region and climatic zone. We explored the association with the locations’ climate characteristics using random effects meta-regression.

Results: The country pooled MMTs ranged from 8.9°C (in Sweden) to 29.9°C (in Taiwan). We observed an increasing North-to-South pattern in the distribution of the MMTs in all the geographical regions. Similarly by climatic zones with increasing MMTs from less-to-warm climates (continental 18.4°C, temperate 21.9°C, arid 24.1°C and tropical 28.7°C). The MMTs increase by 1.5°C for a rise of annual mean temperature of 1°C in arid climates, by 1°C and 0.9°C in tropical and temperate climates respectively, and by 0.2°C in continental climates.

Conclusion: The geographical variation of the MMTs is mainly driven by the temperature distribution and might affect differently according to the climatic zone. Our findings suggest that locations in arid climates are more adapted to heat than those in tropical and temperate climates. Locations in continental climates might not be yet adapted, indicating the need for the implementation of public health policies under climate change.

On behalf of the MCC Collaborative Research Network.

Copyright © 2019 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of Environmental Epidemiology. All rights reserved.