THE ASSESSMENT OF COMORBID PATHOLOGY IN CLEAN-UP WORKERS OF THE ACCIDENT CONSEQUENCES AT THE CHORNOBYL NPP HAVING CARDIOVASCULAR DISEASES

Abstract

Objective. Analysis of comorbid pathology based on the use of methods for its quantitative assessment in persons who were exposed to radiation because of the Chornobyl accident. Materials and methods. Comorbid pathology was studied in 608 men, including 420 clean-up workers (CW) of the accident consequences at the Chornobyl NPP (main group) and 188 non-irradiated persons (control group – CG). All patients had cardiovascular diseases as their main pathology and were examined in the cardiology department of the NRCRM hospital during 2011–2019. The groups did not differ by age, either at the beginning of the accident or at the time of their last examination. Patients of both groups before the accident were practically healthy people and were not registered at the dispensary. The Cumulative Illness Rating Scale (CIRS) was used to quantify comorbid pathology. Results. Comorbid pathology was detected in 418 CW (99.5 %) and 183 patients of CG (99.3 %). The total score in CW (10.3 ± 2.9) units significantly (р = 0.000) exceeded the same index in non-irradiated patients (8.8 ± 3.0) units, as well as the mean number of CIRS categories, whose level severity was 1 point (3.3 ± 1.7 vs. 2.6 ± 1.5, р = 0.000), 2 points (1.8 ± 1.0 vs. 1.6 ± 1.0, p = 0.032) and 3–4 points (1.2 ± 0.8 vs. 1.0 ± 0.9, р = 0.062). In contrast, the mean value of the categories with zero score, i.e. without diseases, was more common in CG (7.8 ± 1.8 vs. 8.8 ± 1.7, р = 0.000). The most common pathology in CW and CG were heart (98.3 % vs. 94.7 %, р < 0.05) and vascular diseases (92.9 % vs. 87.8 %, р > 0.05), followed by diseases of nervous system (79.0 % vs. 57.4 %, р <0.001), musculoskeletal system and skin (69.8 % vs. 56.9 %, р < 0.01), endocrine (56.0 % vs. 49,5 %, р > 0.05) and the respiratory system (53.8 % vs. 53.7 %, р > 0.05) and liver (51.2 % vs. 36.2 %, р < 0.001), which were detected more than in half patients of the main group. Diseases of the kidneys (3.3 % vs. 4.8 %, р > 0.05) and lower gastrointestinal tract (3.3 % vs. 0.5 %, р < 0.01) were quite rare. The incidence of the other four CIRS categories was 18.6–34 %. The total score in subgroups with different ages varied in descending order of mean values as follows: CW > 65 years (10.5 ± 2.9) units, CW < 65 years (9.9 ± 2.8) units, CG > 65 years (9.5 ± 2.8) units and CG < 65 years (7.8 ± 2.9) units with significant differences both between age subgroups in each of the groups and between CW and CG older subgroups. Conclusions. Quantitative assessment of comorbidity by CIRS showed that in persons irradiated during their emergency work due to the Chornobyl accident, the incidence of combined pathology of such organ systems as cardiovascular, nervous, endocrine, hematopoietic, urogenital, musculoskeletal, gastrointestinal, liver and kidneys was significantly higher than in non-irradiated patients. In irradiated patients, the course of comorbid pathology was more severe for each system and in general, reflecting higher values of the total CIRS score. Both among CW and non-irradiated controls, higher values of the total comorbidity score were observed in patients 65 years and older, compared with younger individuals. In both age subgroups of CW the total score was higher than in patients of the control group. Key words: clean-up workers of the accident consequences at the Chornobyl NPP, ionizing radiation, comorbid pathology, chronic diseases.