PREVALENCE AND SEVERITY OF SOMATIC DISTRESS AND FATIGUE AMONG RESIDENTS OF EAST KAZAKHSTAN REGION EXPOSED TO RADIATION DUE TO THE ACTIVITY OF THE SEMIPALATINSK NUCLEAR TEST SITE
Background: since Kazakhstan belongs to the range of industrialized world nations, most of its territory is affected by anthropogenic and man-induced risk factors, which contribute to the development of unfavorable ecological situation that has negative impact on the population health. Nuclear weapons tests at the Semipalatinsk nuclear test site have caused significant adverse changes in the habitat of hundreds of thousands of people who are now forced to live and conduct economic activities in territories contaminated with radionuclides. Studying the long-term effects of small radiation doses on the state of mental functions of local residents appears to be interesting. The stressful situation among the population of contaminated territories was gradually fueled by the dissemination of information on significant and irreversible consequences of nuclear weapons tests on human health. The aim of this study was to investigate the prevalence and severity of somatoform disorders and increased fatigue among residents of Abai and Borodulikha districts affected by long-term tests at the Semipalatinsk Nuclear Test Site, compared with residents of the ecologically safe Kurchum district. Materials and methods. This study had cross-sectional design. To achieve the study aim, a survey was conducted, which covered the population of three districts of East Kazakhstan region: Borodulikha, Abai and Kurchum. The sample size for the Abai district composed 222 people, the sample size for Borodulikha district was equal to 233 people, while the one for Kurchum district (control group) was 245 people. To assess the presence and severity of somatic distress the PHQ-15 scale was utilized, while the Multidimensional Fatigue Inventory (MFI) was used to test the presence of fatigue. The statistical processing of the study results was carried out using the SPSS statistical package (Statistical Package for the Social Sciences) version 20.0 for Windows (GMU Semey). Pearson’s chi-square and Mann-Whitney criterion were used to compare two groups of nominal variables. Differences between groups were considered to be significant if they had a 5% significance level (p <0.05). Results: the prevalence of somatic distress based on the PHQ-15 scale showed the minimal level (0-4 points) among residents of the Abai region in 72.1% of cases as compared to the inhabitants of Borodulikha district and Kurchum village (54.5% and 48.2%, respectively). The differences in the frequency of minimal degree of somatic distress were statistically significant when comparing Abai and Kurchum districts (p <0.001), as well as Abai and Borodulikha districts (p <0.001), but were not significant when comparing Kurchum and Borodulikha districts (p = 0.171475). A mild degree of somatic distress (5-9 points on the PHQ-15 scale) was found in the control group (Kurchum village) more frequently than in Abai and Borodulikha districts (50.2%, 23.6% and 41.9%, respectively). The index of activity decrease in the residents of Abai region was equal to 10.098, which indicates a high degree of fatigue, while in the Borodulikha and Kurchum districts this index appeared to be similar and amounted to 8.184 and 8.158 respectively, which signaled the presence of moderate fatigue. Conclusions: the psychophysiological status of the surveyed population was characterized by the prevalence of general asthenia, decreased activity, manifestation of somatic symptoms of moderate severity, which had a direct dose-effect relationship, i.e. were most pronounced among residents of Abai district, which had the highest doses of radiation.