Survival benefit of continuous positive airway pressure in Japanese patients with obstructive sleep apnea: a propensity-score matching analysis

Study Objectives: Continuous positive airway pressure (CPAP) improves quality of life in patients with obstructive sleep apneas. However, the long-term benefit in all-cause mortality and cardiovascular death are limited among Japanese. Methods: We conducted a retrospective study of patients treated in our sleep clinic in Okinawa, Japan. All patients with full-scale polysomnography from September 1990 to December 2010 were investigated in terms of outcomes such as death (dates and causes of death) between 2012 and 2013 by chart review, telephone calls, and letters of inquiry. Propensity-score matching was performed to balance baseline characteristic differences between a CPAP user group and a nonuser group. The primary outcomes were all-cause mortality and a composite of cardiovascular disease mortality, such as heart disease and stroke, between the two groups. Results: The CPAP user group, almost double in number, had more severe obstructive sleep apnea, more comorbidities, smoking, and alcohol consumption compared to the nonuser group but no significant difference in Epworth Sleepiness Scale. Propensity-score matching selected 1,274 of 4,519 patients as the CPAP user group and 1,274 of 2,128 as the CPAP nonuser group. Mean age of the patients was 52.3 (+/- 13.5) years and 79% were men. After a median follow-up of 79 (interquartile interval, 24 to 128) months in the CPAP user group and 73.5 (interquartile interval, 26 to 111) in the non-CPAP group, death from all causes occurred in 53 (4.2%) patients in CPAP user group and in 94 (7.4%) patients in CPAP nonuser group. The leading cause of death was malignancy in each group. The hazard ratios for all-cause mortality and cardiovascular disease deaths were 0.56 (95% confidence interval (CI), 0.41-0.78) and 0.54 (95% CI, 0.28-1.03) between CPAP user group and CPAP nonuser group, respectively. Conclusions: In obstructive sleep apnea patients, CPAP use was associated with lower all-cause mortality.