The Association between All-cause Mortality and Obstructive Sleep Apnea in Adults: A U-Shaped Curve.

Rationale and Objectives: The relationship between Sleep Apnea (SA) and mortality remains a topic of debate. We explored the relationship between the severity of SA and mortality and the effect of age on this association. Methods: Using a Veterans' database, we extracted the apnea-hypopnea index (AHI) from physician interpretation of sleep studies, by developing a Natural Language Processing (NLP) pipeline (with 944 manually annotated notes) which achieved more than 85% accuracy. We categorized the participants into no-SA (n-SA, AHI< 5), mild to moderate SA (m-SA, 5 ≤AHI<30), and severe SA (s-SA, AHI≥30). We propensity-matched the m-SA and s-SA categories with n-SA based on age, sex, race, ethnicity, body mass index (BMI) and 38 components of the Elixhauser Comorbidity index. Using logistic regression, we estimated the odds ratio (OR) for all-cause mortality using m-SA as a reference. Also, we stratified the findings based on age: Young ≤40; Middle-aged >40 and<65; and Older ≥65 adults. Measurement and Main Results: We extracted AHI on 179,121 propensity-matched participants (age, 45.85±14.1; BMI 30.15±5.37 kg/m2; 79.09% male; 64.5% White). All-cause mortality rates among 3 AHI categories showed a U-shaped curve (11.55%, 7.07%, and 8.15% in the n-SA, m-SA, and s-SA, respectively) regardless of age groups. Compared to m-SA, the odds of all-cause mortality in n-SA (OR, 1.72; 95%CI:1.65,1.79) and s-SA (OR, 1.17;95%CI:1.12,1.22) were higher. Stratifying by age yielded consistent findings. Conclusions: All-cause mortality showed a U-shaped association with AHI. Further investigations to understand the underlying mechanisms of this phenomenon are warranted.