Dose- and age-dependent cardiovascular mortality among inhabitants of the Chornobyl contaminated areas. 1988-2010 observation period.

Objective. The goal of this study was to conduct a descriptive epidemiological analysis of cardiovascular disease mortality among people living in contaminated areas of Ukraine with regard for total cumulative effective doses and age at the time of the Chornobyl accident. Materials and methods. Depending on respective total cumulative effective doses for 1986-2010 the people living in contaminated areas of Ukraine were divided into cohorts of those exposed to 5.6-20.99 mSv (cohort 1) and 21.00-50.99 mSv (cohort 2) radiation doses. Each one was stratified by age categories - younger than 18 years old, aged 18-39 and 40-60 respectively. Death rate (ID/10^3 person-years) and mean error (±m) were calculated and Student's test (t) was applied to estimate the mortality from cardiovascular diseases for 1988-2010 period. Results. The significantly higher (ID/10^3 person-years is 8.08 ± 0.10) cardiovascular disease mortality was revealed within 1988-2010 observation period among inhabitants of contaminated areas exposed to 21.00-50.00 mSv total effective radiation doses accumulated over 1986-2010 as compared to that in cohort 1 (ID/10^3 person-years is 6.29 ± 0.06) for the same period. In the age groups (under 18, 18-39 and 40-60 years old) exposed to 21.0-50.0 mSv doses the mortality rate was significantly higher than in the corresponding age groups of the inhabitants with 5.6-20.99 mSv exposure (1.31 ± 0.08 ID/10^3 person-years, 8.50 ± 0.19, 48.95 ± 0.33 vs 0.75 ± 0.04, 5.00 ± 0.11, 23.52 ± 0.24 respectively). In the elder age groups with higher radiation doses the mortality was significantly higher (p < 0.05) than in those with lower doses: ID/10^3 person-years was 1.31 ± 0.08 vs. 0.75 ± 0.04 (those under 18 years); 8.50 ± 0.19 vs. 5.00 ± 0,11 (those aged 18-39); 48.95 ± 0.33 vs. 23.54 ± 0.24 (people aged 40-60). Among inhabitants with higher radiation doses the mortality rates for certain groups of cardiovascular diseases (coronary heart disease, cerebrovascular disease, arterial hypertension, diseases of arteries, arterioles and capillaries) were significantly higher compared to those having lower radiation doses. Conclusions. Cardiovascular mortality among inhabitants of contaminated areas of Ukraine is dependent on the total cumulative effective doses and age at the time of the Chornobyl accident. It is proved by a significantly higher (p < 0.05) mortality in people exposed to 21.00-50.0 mSv radiation doses compared to those having 5.6-20.99 mSv exposures. Mortality was significantly higher (p < 0.05) in age groups with higher doses as opposed to those with low ones. Maximum mortality was observed among inhabitants aged 40-60, while the lowest death rate in patients younger than 18 years old. The data obtained also suggest that the radiation factor can be considered here as one accelerating the aging and pathophysiological abnormalities in survivors. Coronary heart disease, cerebrovascular disease, arterial hypertension, diseases of arteries, arterioles and capillaries are the main causes of death from cardiovascular disease in people under investigation.