Trends of Age-Specific Mortality with an Underlying or Contributing Cause Attributed to a Weather-Related Cause of Death in Japan, 1995-2015

Abstract

Objective: To observe the effect of climate change on the mortality of the elderly and children, we examine age-specific heat-related(HM) and cold-related mortality(CM), and other weather-related mortality during 1995-2015 in Japan.Method: Deaths with an underlying or contributing cause attributed to a weather-related cause of death were included. Heat-related death certificate of ICD-10 codes X30 (exposure to excessive natural heat), T67(heatstroke or sunstroke), cold-related deaths X31(exposure to excessive natural cold), T68(hypothermia), flood-storm-lightning-related deaths. Odds ratios(OR) for weather-related deaths by sex, age group, and period group were obtained using logistic regression.Results and Conclusion: About 93,000 Japanese died from weather-related cause of death (0.41 percent of total death) during 1995-2015. CM tended to have a higher mortality than HM. The tendency was remarkable in male. OR of gender difference between HM and CM is 1.30(1.25-1.35). Based on the mortality at the age group of 40-45 years, the risk of heat-related death increased with aging and increased significantly over aged 80-84(OR 16.9 in X30). CM tended to be similar to HM, and no difference was observed. As a result of analysis in the summer weather in two groups of hot and warm summer, the effect on the mortality of hot weather of elderly people over 80 years old was remarkable as the increase of HM (OR 2.71). There was a tendency that the decrease of CM was lower in the hot summer. For children, HM increased by 2.94 times (aged 10-14, 2003), 2.31 times (aged 15-19, 2011) in the hot summer, but the increase in mortality did not show a certain trend.The differentials in weather-related mortality observed among older people over 80 years old were consistent with previous studies. This study made it possible to better understand the trend of weather-related mortality by observing age-specific mortality.This work was supported by JSPS KAKENHI Grant Number JP17K01829.