Seasonal mortality variations of cardiovascular, respiratory and malignant diseases in the City of Belgrade

The main purpose of this paper is to examine seasonal variations in mortality resulting from cardiovascular diseases, respiratory diseases and cancer, as well as to provide a review of environmental factors underlying such phenomenon. The herein presented study was conducted on the territory of Belgrade based on the data on daily mortality rates obtained from the Institute of Public Health in Belgrade for the period 2009-2014, as well as the data on annual mortality rates provided by the Statistical Office of the Republic of Serbia for the period 2000-2014. The analysis of mortality variations was performed by the use of Theil-Sen method, smooth trend method and cubic spline interpolation, whereas desriptive tools, such as winter/summer ratio and dissimilarity index, were used to examine the seasonal pattern. According to the Institute of Public Health, over 113430 deaths were registered in Belgrade area for the period 2009-2014, out of which 53.25% is attributed to cardiovascular diseases, 4.01% to respiratory diseases and 27.50% to cancer. The annual mortality rates caused by cardiovascular diseases and cancer on the territory of Belgrade are among the highest ranking in Europe. The leading causes of death in the observed period included: cardiomyopathy, heart attack and stroke with accompanying complications, breast cancer in women, prostate and colorectal cancer in men, lung and bronchus cancer for both genders, and chronic obstructive pulmonary disease. Cardiovascular and respiratory mortality rates are significantly higher among people aged 65 and over, whereas more than one third of deaths caused by cancer is observed among younger people aged between 45 and 64 years. Research results show that seasonal variations were most pronounced in mortality resulting from cardiovascular and respiratory diseases, with highest mortality rates recorded in February and March and lowest during the summer season. Also, the number of deaths due to cardiovascular diseases increased twice, namely at the end of June and October, which is assumed to be the result of sudden temperature changes. Nonetheless, no such seasonal variations were observed in mortality caused by cancer. Seasonal variations in mortality resulting from cardiovascular diseases also indicate gender differences, which is why sudden temperature changes in interim periods affect more women than men. As regards deseasonalized trend, mortality caused by cardiovascular diseases stagnates, while mortality caused by cancer and mortality caused by respiratory diseases records moderate to severe increase. This is a uniform trend in almost all municipalities in Belgrade, with average mortality rates being higher in central zones than in suburbs over the last 15 years, particularly mortality caused by cancer. A slight increase in the overall mortality can also be attributed to aging of the population, which cannot be verified due to lack of available accurate data on the average age structure of Belgrade population for the observed period. A better understanding of seasonal variations in mortality caused by chronic non-communicable diseases can contribute to improving the population health care and rising awareness of the population concerning greater health care in changeable weather conditions due to global warming and climate change. These findings can also enhance preventive action on environmental risk factors that are not limited exclusively to weather conditions, such as air pollution.