Disc Degeneration in Military Personnel: A Systematic Review and Meta-Analysis for NASA Astronaut Preflight Imaging

Study Design: Systematic review and meta-analysis. Objective: To systematically review and meta-analyze spine magnetic resonance imaging (MRI) data from military personnel to characterize occupational risk factors for disc degeneration before spaceflight. Summary of Background Data: Approximately 60% of NASA astronauts have military backgrounds, potentially predisposing them to higher risk of spinal pathology. We evaluated data on disc degeneration in military personnel compared with an asymptomatic civilian population to estimate spinal pathology prevalence among NASA astronauts with military backgrounds. Methods: PubMed, Scopus, and Google Scholar databases were systematically queried in April 2024 using the MeSH terms: military personnel, spine, and MRI. Studies involving asymptomatic civilians from a prior systematic review served as a control population. A mixed-effects meta-analysis and linear regression were conducted to compare disc degeneration and average age between military and civilian populations. Results: There was a significant group effect, with military personnel showing higher overall prevalence of disc degeneration compared with civilians ( =0.999; 95% CI: 0.588, 1.4110; P