Impact of diurnal temperature variations on hospitalization due to cardiovascular and respiratory diseases in Rafsanjan, Iran, in 2008-2013

Background: Changes in global temperature and its health effects have recently been under much investigated. Consequently, these changes have affected mortality and morbidity rates which are important public health indices. The present study examines the effect of mean temperature on the frequency of hospitalization due to cardiovascular and respiratory diseases in Ali Ibn Abi Talib Hospital of Rafsanjan, Iran. Materials and Methods: In this ecological study, data on hospitalization were gathered from electronic systems of hospitals and the data from the weather organizations were extracted from the weather station. All patients not living in Rafsanjan were excluded. Data were entered into SPSS and SAS software and the association between mean temperature and hospitalization frequency were analyzed using Poisson regression models. Results: A negative significant association was found between mean temperature and mean number of hospitalizations due to cardiovascular and respiratory diseases. By each 1 °C decrease in mean temperature, the mean number of hospitalizations due to cardiovascular and respiratory diseases increased by 1% (95% CI 0.63-1.26%) and 4.33% (95% CI 4-4.64%), respectively. For cardiovascular diseases, there was no significant difference in mean number of admissions based on different age groups. However, in the 0-4-year age group, the mean number of hospitalizations due to respiratory diseases was significantly higher than the other age groups. For both cardiovascular and respiratory diseases, there was no significant difference between females and males in terms of the mean number of hospitalizations. Conclusions: Reduction in mean temperature, in the present study, increased the mean number of hospitalizations due to cardiovascular and respiratory diseases and it was stronger for respiratory diseases. According to these findings, people who are at risk of cardiovascular and respiratory diseases should be forbidden from exposure to extremely cold temperatures.