All-Cause Mortality and Obstructive Sleep Apnea Revisited

Abstract

Objective: Obstructive Sleep Apnea Syndrome (OSAS) is a pervasive problem that affects millions worldwide. OSAS is strongly linked to hypertension, coronary artery disease, and stroke. However, its association with mortality is not clearly quantified. A large database of patients who underwent sleep testing was explored for associations with all-cause mortality.

Method: Over 77,000 patients who underwent a validated, portable sleep study (SNAP Test, SNAP Diagnostics Inc, USA) were matched to the Social Security Death File to establish mortality. Measures of OSAS severity and other major confounding factors were correlated to all-cause mortality using survival analysis with multivariate Cox proportional hazards regression.

Results: As expected, increasing age (adjusted HR = 1.08095%CI = 1.074-1.086 P < .0001), BMI (HR = 1.042 95%CI = 1.033-1.051 P < .0001), and male sex (HR = 1.378 95%CI = 1.190-1.595 P < .001) were associated with increased all-cause mortality. Epworth sleepiness score was also associated with mortality (HR = 1.015 95%CI = 1.005-1.025, P = .002). Apnea Hypopnea Index (AHI) was NOT associated with mortality after adjustment for age (HR = 1.001 95%CI = 0.998-1.004, P = .416). However within 10-year age subgroups, desaturation index (41-50 year olds, adjusted HR = 1.217 95%CI = 1.014-1.461, P = .035), Apnea Index (21-30 year olds, HR = 1.632 95% CI = 1.053-2.532 P = .028), and AHI (31-40 year olds, HR = 1.222 95% CI = 1.010-1.478 P = .039) were significantly associated with all-cause mortality in younger patients. In older patients (over 50 years), age, sex, and BMI were dominantly associated with mortality.

Conclusion: Increasing OSAS severity as measured by a validated home sleep test and quantified by AHI, Apnea index, and pulse oximetry desaturation index, is independently associated with a modestly increased all-cause mortality in younger patients (less than age 50 years) after adjustment for major confounding factors.