The relation between mortality from cardiovascular diseases and temperature in Shiraz, Iran, 2006-2012

Several studies have suggested that temperature may have an effect on the number of cardiovascular deaths in societies. Global warming is a concern, and cardiovascular diseases are the top cause of death worldwide. This study investigated the relation between temperature and cardiovascular mortality in Shiraz City, Iran.

In this ecological study, data about temperature and cardiovascular deaths (in age and gender groups) in Shiraz City were inquired from 2006 to 2012. The simultaneous and delayed relation between monthly temperature and cardiovascular deaths was examined using Spearman and Pearson correlation tests, and crude and adjusted negative binomial regression analysis with adjustment for confounding factors such as humidity, rainfall, wind direction, wind speed, and air pollutants. Analysis was done using MINITAB and STATA software.

During this period 17,167 deaths were reported in Shiraz. The lowest number of cardiovascular deaths was reported in 20 °C. No significant relation was observed between mean monthly temperature and cardiovascular deaths in the same month after adjusting for confounding factors. Although, cardiovascular death in 18- to 60-year-old people showed an inverse significant relation with minimum [Incidence rate ratio (IRR) = 0.98989, P = 0.020], maximum (IRR = 0.99046, P = 0.011), and mean temperature (IRR = 0.98913, P = 0.006) of the same month in the crude model, it was not significant in the adjusted model (IRR = 0.99848, P = 0.848, IRR = 0.99587, P = 0.584, and IRR = 0.99512, P = 0.506, respectively).

It seems that there is no significant relation between temperature and cardiovascular deaths in Shiraz, which is probably due to its moderate climate, and the fact that no major heat or cold wave occurred during this time.