Comparison of the temperature-mortality relationship in foreign born and native born died in France between 2000 and 2009

Abstract

The daily temperature-mortality relationship is typically U shaped. The temperature of minimum mortality (MMT) has been shown to vary in space (higher at lower latitudes) and time (higher in recent periods). This indicates human populations adapt to their local environment. The pace of this adaptation is unknown. The objective of this study was to investigate the differences in the temperature-mortality relationship in continental France between foreign born and natives. Source data were the 5,273,005 death certificates of individuals living in continental France between 2000 and 2009 at the time of their death. Foreign-born deaths (N = 573,384) were matched 1:1 with a native-born death based on date of birth, sex, and place of death. Four regions of France based on similarity of their temperatures profiles were defined by unsupervised clustering. For each of these four regions, variations of all causes mortality with season and temperature of the day were modeled and compared between four groups of foreign born (Maghreb, sub-Saharan Africa, Southern Europe, and Northern Europe) and matched groups of natives. Overall, the temperature-mortality relationship and MMT were close in foreign born and in native born: The only difference between foreign born and native born concerned the attributable mortality to cold, found in several instances larger in foreign born. There are little differences in France between the temperature-mortality relationships in native born and in foreign born. This supports the hypothesis of an adaptation of these populations to the temperature patterns of continental France, which for those born in Africa differ markedly from the climatic pattern of their birth country.

Keywords: Adaptation; Climate change; Minimum mortality temperature; Mortality.