The Association between All-Cause Mortality and Obstructive Sleep Apnea in Adults: A U-Shaped Curve
Mehrnaz Azarian, Amin Ramezani, Amir Sharafkhaneh, Arash Maghsoudi, Meir H. Kryger, Robert J. Thomas, M. Brandon Westover, Javad Razjouyan
Abstract
Abstract Rationale The relationship between sleep apnea (SA) and mortality remains a topic of debate. Objectives 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 an apnea–hypopnea index (AHI) from physician interpretations of sleep studies by developing a natural language processing 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 on the basis of age, sex, race, ethnicity, body mass index, 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 on the basis of age: young, ⩽40; middle aged, >40 and <65; and older, ⩾65 adults. Results We extracted the AHI on 179,121 propensity-matched participants (mean age = 45.85 [SD = 14.1]; BMI = 30.15 ± 5.37 kg/m2; male, 79.09%; White, 64.5%). All-cause mortality rates among three AHI categories showed a U-shaped curve (11.55%, 7.07%, and 8.15% for n-SA, m-SA, and s-SA, respectively), regardless of age group. Compared with m-SA, the odds of all-cause mortality in n-SA (OR, 1.72; 95% confidence interval = 1.65–1.79) and s-SA (OR, 1.17; 95% confidence interval = 1.12–1.22) were higher. Stratifying by age yielded consistent findings. Conclusions All-cause mortality showed a U-shaped association with the AHI. Further investigations to understand the underlying mechanisms of this phenomenon are warranted.