Mortality among Chernobyl emergency workers from 1992 over 2010: analysis of data of the National Radiation and Epidemiological Registry

The authors analyzed data on mortality in the Russian cohort of Chernobyl emergency workers, accumulated at the National Radiation and Epidemiological Registry from 1992 over 2010. The cohort consisted of 74814 male residents of 6 administrative units of Russia including 20183 deaths. Analysis of radiation risks of mortality was made with Cox regression model and Kaplan-Meier method for all-cause mortality and survival analysis of some causes of death with account of competing risks. Radiation-induced risks of mortality in the cohort under study were shown to be statistically significant. Risk of all-cause mortality is 0.23 (95 % CI: 0.2; 0.45), risk of mortality from all solid cancers (ICD-10 codes: C00-C80) is 0.57 (95 % CI: 0.00; 0.81), from circulation diseases (ICD-10 codes: I00-I99) is 0.46 (95 % CI: 0.12; 0.84). The magnitude of radiation-induced risk of mortality from hypertension (ICD-10 codes: I10-I15) is the greatest and statistically significant – 2.52 (95 % CI: 0.69; 5.15). Radiation-induced risks estimated by competing risks survival analysis and Cox regression are close to the majority of causes of death. It indicates that the used methods can be applied to the analysis of radiation risks in large cohorts.