Background: Although continuous positive airway pressure (CPAP) has become the first line of therapy for obstructive sleep apnea (OSA), it remains controversial whether non-sleepy patients could benefit from CPAP treatment.
Methods: We searched the online databases Medline, Embase, the Cochrane library and the Cochrane Central Registry of Controlled Trials to select eligible control trials, including non-sleepy OSA patients and those patients treated by CPAP or either sham CPAP or no CPAP.
Results: Seven eligible studies (1,541 patients) were included. The pooled estimates of the mean changes after CPAP treatment for the systolic blood pressure (SBP) and diastolic blood pressure (DBP) were -0.51 mmHg (95% CI, -3.39 to 2.38 mmHg; P=0.73) and -0.92 mmHg (95% CI, -1.39 to -0.46 mmHg; P<0.001), respectively. CPAP should not improve subjective sleepiness in the minimally symptomatic OSA patients, as the change in the Epworth sleepiness scale (ESS) was -0.51 (95% CI, -1.68 to 0.67; P=0.397). However, CPAP can effectively reduce AHI or ODI by 15.57 events/h (95% CI, -29.32 to -1.82; P=0.026) compared to controls. However, the risk of cardiovascular events did not significantly decrease [odds ratio (OR), 0.80; 95% CI, 0.50 to 1.26; P=0.332] in the end.
Conclusions: CPAP treatment can reduce OSA severity in non-sleepy patients and minutely reduce the DBP, but CPAP seems to have no overall beneficial effects on subjective sleepiness, SBP, or cardiovascular risk.
Keywords: Sleep apnea; cardiovascular diseases; continuous positive airway pressure/method (CPAP/method); hypertension; obstructive/complications/therapy.