The changes of AHI after long-term CPAP in patients with comorbid OSA and cardiovascular disease

Purpose: To evaluate the effect of long-term continuous positive airway pressure (CPAP) treatment on disease severity of obstructive sleep apnea (OSA). Methods: We analyzed results from the Sleep Apnea and Cardiovascular Events (SAVE) study involving participants recruited at the Guangdong Provincial People’s Hospital, China. Participants were aged 45–75 years with a history of cardiac or cerebrovascular disease. OSA was confirmed by home sleep apnea testing (HSAT). Participants were randomized to receive CPAP plus standard cardiovascular care (CPAP group) or standard care alone (UC group) and followed for several years. At the study conclusion, surviving participants were invited to repeat HSAT. Changes in OSA indicators were compared by independent samples t-tests and subgroup analysis was implied among groups stratified by OSA severity. Results: One hundred two adults were recruited (51 per group) and followed for 48.0 ± 14.5 months. Daily CPAP usage in the CPAP group was 4.1 ± 1.9 h. AHI decreased from baseline to end-of-study in both CPAP and UC groups (− 5.0 (− 12.5,2.0), P = 0.000; − 4.0 (− 12.5,1.5), P = 0.007, respectively), with no between-group difference (P = 0.453). An improvement in nadir SpO₂ showed from baseline to end-of-study in the CPAP but not UC group (2.3% ± 6.1%, P = 0.011 and − 0.7% ± 7.6%, P = 0.511, respectively; between-group difference P = 0.032). Subgroup analysis shows that CPAP could improve AHI in patients with moderate OSA (− 8.0 (− 11.8, − 2.8) in CPAP group, − 2.0 (− 0.8,6.0) in UC group, P = 0.022) and improve nadir SpO₂ in patients with severe OSA (5.0 (− 0.8, − 0.8,7.0) in CPAP group, 0.0 (− 8.5,2.5) in UC group, P = 0.032). Conclusion: Long-term CPAP use did not result in clinically significant changes in AHI or ODI overall but showed variable effects stratified by OSA severity.