Design and current status of the longitudinal study of astronaut health

Background: Information has been collected regarding the immediate physiolo gical effects of spaceflight on humans. However, little is yet known regard ing long-term effects. The purpose of this paper is to describe the Longitu dinal Study of Astronaut Health (LSAH) and report current mortality data. M ethods: All astronauts selected for the United States Space Program are fol lowed from selection throughout their lifetime or until the end of the stud y. Comparisons are ground-based Johnson Space Center (JSC) employees matche d to the astronauts at a 3:1 ratio by sex-specific age and body mass index. They are followed in the same manner as astronauts. Morbidity and mortalit y data are obtained from medical records supplemented with study questionna ires. Checks for death certificates are made to ascertain death of particip ants who miss routine examinations. Results: Current cause-specific mortali ty rates for astronauts selected from 1959 through 1991 are not statistical ly different from rates for comparison participants fbr cardiovascular (p = 0.8112), cancer (p = 0.2382), or other disease (p = 0.5040) mortality. Ast ronauts have a significantly higher mortality rate due to accidents and inj uries (p < 0.0001). Conclusions: Astronauts have a similar risk of death du e to chronic diseases as ground-based participants, but are at greater risk for occupational-related accidental death.