Hypoxia During Sleep and the Risk of Falls and Fractures in Older Men: The Osteoporotic Fractures in Men Sleep Study

OBJECTIVES: To test the hypothesis that low arterial oxygen saturation during sleep is associated with a greater risk of falls and fractures. DESIGN: Prospective cohort study. SETTING: Six U.S. clinical centers. PARTICIPANTS: Men aged 67 and older (N = 2,911). MEASUREMENTS: The primary exposure measure was percentage of sleep time with arterial oxygen saturation less than 90% measured using polysomnography. The main outcome measures were incident falls within 1 year and incident nonspine fractures over an average follow-up of 6.8 years. RESULTS: Men with 10% or more of sleep time at an arterial oxygen saturation of less than 90% were older, reported more comorbidities, had poorer physical function, and were more likely to have sleep disordered breathing than men with less than 10% sleep time at an arterial oxygen saturation of less than 90%. After multivariate adjustment, men with 10% or more of sleep time with arterial oxygen saturation of less than 90% had a greater risk of having one or more falls (relative risk (RR) = 1.25, 95% confidence interval (CI) = 1.04-1.51) and two or more falls (RR = 1.43, 95% CI = 1.06-1.92) than those with less than 10% of sleep time with less than 90% arterial oxygen saturation. Men with greater percentage of sleep time with arterial oxygen saturation less than 90% had a 30% to 40% greater risk of nonspine fracture than those with normal nocturnal oxygen saturation in models adjusting for sleep disordered breathing. CONCLUSION: Hypoxia during sleep may be a risk factor for falls and fractures in older men. Interventions aimed at decreasing nocturnal hypoxia may decrease falls and fractures.