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A Cohort Mortality Study Among Soviet and Russian Cosmonauts, 1961-2014.

INTRODUCTION
Over 500 people from different countries have been to space since the first manned spaceflight in 1961. Factors of space and spaceflights might cause functional and somatic disorders, leading to increased mortality. Our research goal was to assess cause-specific risk of death among Soviet and Russian cosmonauts who had at least one spaceflight.


METHODS
The epidemiological cohort study included 115 male cosmonauts. The observation period was 54 yr (January 1, 1961-December 31, 2014) and 2707 person-years of follow-up were obtained. By the end of the period, 84 cosmonauts were still alive and 31 were deceased. The reference groups were the male population of Russia and of the Moscow Region, where Zvezdny City (Star City) is located. Mortality risk was assessed by standardized mortality ratio (SMR) with 95% confidence intervals (95% CI).


RESULTS
Death risk in the cohort was significantly lower than that in both reference groups: for all causes (А00-Y98; SMR = 40), for diseases of the circulatory system (I00-I99; SMR = 37 and 35 compared to Russia and the Moscow Region, respectively), and for other causes, i.e., all causes except circulatory diseases, cancer, and accidents, (SMR = 8). Death risk for accidents (V01-Y98) in the cohort was 1.8-1.9 times lower than that in both reference groups: SMR = 52 (95% CI 19-139) and 56 (21-151), but was not statistically significant. SMR for cancer (C00-C97) was also below 100 (71 and 66), but insignificant.


DISCUSSION
Our findings mainly characterize mortality among the first cosmonauts who have flown to space from 1961 through the 1970s, which indicates the necessity of continuing research.Ushakov IB, Voronkov YI, Bukhtiyarov IV, Tikhonova GI, Gorchakova TYu, Bryleva MS. A cohort mortality study among Soviet and Russian cosmonauts, 1961-2014. Aerosp Med Hum Perform. 2017; 88(12):1060-1065.