Efficacy and safety of continuous positive airway pressure on blood pressure in patients with obstructive sleep apnea: an overview of systematic reviews and meta analyses

Introduction Obstructive sleep apnea (OSA) is a prevalent disorder associated with significant cardiovascular morbidity, including hypertension. Continuous positive airway pressure (CPAP) is the primary treatment for OSA and has been proposed as an adjunctive therapy for hypertension. However, evidence regarding its antihypertensive effects remains heterogeneous, with many studies exhibiting low methodological quality. Methods A comprehensive computerized search of PubMed, Embase, the Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), VIP, Wanfang, and the China Biology Medicine disc (CBM) databases was conducted from their inception to December 1, 2025, to systematically identify systematic reviews and meta-analyses examining the effect of continuous positive airway pressure (CPAP) on blood pressure in patients with obstructive sleep apnea (OSA). A citation overlap matrix was constructed, and the corrected covered area (CCA) was calculated to assess the degree of overlap among primary studies. The ROBIS, AMSTAR-2, PRISMA 2020, and GRADE tools were used to evaluate the risk of bias, methodological quality, reporting quality, and certainty of evidence of the included systematic reviews/meta-analyses, respectively. Quantitative and qualitative analyses were conducted on the primary outcomes to gain a more comprehensive and in-depth understanding. Results This umbrella review included a total of 17 systematic reviews/meta-analyses. The citation matrix analysis yielded a corrected coverage area of 14.2%, indicating a substantial degree of overlap among the primary studies, which may artificially inflate the perceived consistency of findings. Methodological quality assessment using AMSTAR-2 revealed a critical limitation that fundamentally shapes the interpretation of this overview: only 3 out of 17 included reviews were rated as high quality, while the remaining 14 (82.3%) were judged to be of low quality. This widespread methodological weakness—primarily driven by lack of pre-registered protocols, inadequate integration of risk of bias into conclusions, and poor reporting of funding sources—directly undermines the reliability of the conclusions drawn by these individual reviews and, by extension, the overall findings of this overview. The GRADE assessment of evidence certainty showed that among all evaluated outcomes, only 4 were rated as high quality, 29 as moderate, 51 as low, and 25 as very low. Discussion Current evidence suggests that continuous positive airway pressure (CPAP) therapy is associated with modest reductions in blood pressure among patients with obstructive sleep apnea, particularly in nocturnal measures. The therapy appears generally well-tolerated with no serious adverse events reported. However, these findings should be interpreted with caution due to the predominantly low-to-very-low certainty of the evidence, substantial methodological weaknesses in the included reviews, and significant overlap of primary studies. The magnitude of blood pressure reduction may be influenced by factors such as CPAP adherence and baseline hypertension severity, although these could not be robustly explored due to limitations in the included literature. Future research should employ large-scale, long-term real-world studies with standardized reporting of CPAP intervention details (e.g., device type, adherence, pressure settings) and diverse outcome measures such as ambulatory blood pressure monitoring. Such studies are needed to clarify the differential efficacy of CPAP across distinct clinical subgroups and its long-term cardiovascular benefits, thereby informing more precise clinical practice guidelines. Systematic review registration https://www.crd.york.ac.uk/PROSPERO/ ; CRD420251239607.