Shoulder consultations and surgery incidence rates in NASA astronauts and a cohort population of working individuals

Abstract

Individuals frequently seek medical care for musculoskeletal disorders of the shoulder and astronauts are no different. The purpose of this study was: 1) to determine the impact of age and sex as risk factors for orthopedic shoulder consultations and surgery in a cohort population; and 2) to determine if NASA astronauts are at a higher risk for consultations and surgery than a cohort population. The cohort (n = 347,540) was a group of working individuals that participated in a capitated insurance plan managed by their employers over a 10-year period. The astronaut cohort was comprised of NASA astronauts selected from 1959 through December 31, 2014 (n = 338). Both populations were limited to individuals between 25 and 64 years. Incidence rates indicate that age and sex were risk factors for consultation and surgery. As age increased, consultations increased significantly for both sexes in a stair-step manner. Males consistently had a higher rate than females in all age categories (all p ≤ 0.001) except for 55-64 year-olds (p = 0.228). Survival analysis confirmed that age (p < 0.001) was a significant risk factor and that male astronauts had a higher rate of consultations (p < 0.001) but not surgery (p = 0.938) as compared to the male cohort. The consultation rates were not significantly different in females when accounting for follow-up time (p = 0.14). Cohort data show that both age and sex were risk factors for consultation and surgery. Additionally, male astronauts were referred to orthopedists more often than the cohort population, but surgery rates did not differ between groups.