Associations of ambient temperature with mortality rates of cardiovascular and respiratory diseases in Taiwan: A subtropical country

Background: We conducted a time-series analysis of daily ambient temperature and all-cause, cardiovascular, and respiratory disease mortality in Taiwan, which is generally neither extremely hot nor cold. Methods: Data on all-cause daily mortality rates (excluding accidents, suicide, and homicide), and mortality rates due to respiratory and cardiovascular diseases between 2008 and 2010 were obtained from the Taiwan Death Registry. The daily temperature for that period was averaged from 33 monitoring stations nationwide. A generalized least square model was constructed to assess the relationship between the time-series trends of temperature and mortality, and the cross-correlation function was used to determine the possible time lag for the effect of temperature on mortality. Results: As the average temperature increased, the daily all-cause (β = -0.006) and respiratory disease (β = -0.012) mortality rates decreased. On the other hand, an inverse relationship (β = -0.028) between average daily temperature and cardiovascular disease mortality was observed only for a temperature between 12.91 °C and 26.36 °C. The time lag for all-cause and cardiovascular disease mortality was similar at 4-6 days, while the lag for respiratory disease was longer at 13-16 days. Conclusions: We found inverse associations between average temperature and all-cause and respiratory mortality. An inverse association between temperature and cardiovascular disease mortality was observed only from 12.91 °C to 26.36 °C.