Effects of CPAP on Blood Pressure Parameter Across Different Severities of Obstructive Sleep Apnoea: A Meta-Analysis

In an unselected obstructive sleep apnoea (OSA) population, continuous positive airway pressure (CPAP) slightly lowers blood pressure (BP). The aim was to investigate the differential effects of CPAP on BP in different OSA severities. Medline was searched through December 2023 for randomised controlled trials (RCTs) on the effect of CPAP compared to an inactive control on office, 24 h, diurnal and nocturnal systolic and diastolic BP in OSA. A random-effects meta-analysis was performed at the study level for the different BP measures; meta-regression and subgroup analyses were used to examine the effects of OSA characteristics and CPAP use. Seventy-five RCTs (10,025 patients) were included. CPAP lowered office, 24 h, diurnal and nocturnal systolic BP (SBP) by -2.5 (95% CI -3.8 to -1.2; nRCTs = 40), -2.6 (95% CI -3.6 to -1.6; n = 29), -2.2 (95% CI -3.2 to -1.3; n = 32) and - 3.5 (95% CI -4.4 to -2.5; n = 32) mmHg, respectively. In the meta-regressions, higher 24 h and diurnal SBP and longer nocturnal CPAP use were significantly associated with greater BP reduction (all p < 0.05). In subgroup analyses, the reduction in 24 h, diurnal, and nocturnal SBP was greater in studies with an apnoea-hypopnoea index ≥ 30/h compared to mild OSA. CPAP use ≥ 5 h/night had a greater impact on lowering 24 h and nocturnal SBP (-4.2 vs. -2.1, p = 0.05, and -4.2 vs. -1.6 mmHg, p = 0.01). CPAP has the strongest BP-lowering effect on nocturnal blood pressure, which is, particularly, relevant prognostically and the effect is stronger at higher baseline BP and with CPAP use of ≥ 5 h. Study Registration: The systematic review and meta-analysis has been registered on PROSPERO: CRD42023477227.