Adjusted hazard ratios (95% confidence intervals) for the association between the central apnea index and all-cause mortality stratified by sex and age.

aModel 1: Adjusted for age (continuous) and race. Hazard ratios were derived comparing the lower three quartiles to the fourth quartile of the central apnea index.
bModel 2: Adjusted for covariates of model 1 (except sex) and body mass index (continuous).
cModel 3: Adjusted for covariates of model 2 and smoking status (never, former, current), hypertension, diabetes, and cardiovascular disease.
dSex was included as a covariate in each of the three models based on all participants.