Effect of continuous positive airway pressure on blood pressure in normotensive individuals with obstructive sleep apnoea: a randomised trial

Abstract

Background: The effects of continuous positive airway pressure (CPAP) on blood pressure (BP) in normotensive subjects, particularly among those with a dipping BP pattern, remain uncertain, raising questions about its indication for this group of patients. We assessed the impact of CPAP on BP in normotensive subjects with a dipping BP pattern and severe obstructive sleep apnoea (OSA).

Methods: This was a randomised, parallel, prospective, controlled trial. Inclusion criteria were: age ≥18 years, apnoea-hypopnoea index ≥30 events·h^-1, mean 24-h BP <130/80 mmHg and daytime to night-time BP reduction ≥10%. Patients were randomly assigned to receive either CPAP treatment or usual care for 12 weeks. The primary outcome was the change in ambulatory BP monitoring (ABPM) parameters from baseline to the 3-month follow-up.

Results: The 60 patients who completed the follow-up had a mean±sd age of 52.2±10.8 years and 40 (66.7%) were male. The intention-to-treat analysis showed no significant changes with CPAP, whereas the usual care group experienced increases in ABPM parameters. This resulted in a mean difference of -3.4 mmHg (95% CI -6.124- -0.676; p=0.015) in night-time diastolic BP between the groups. The per-protocol analysis indicated significant differences between the CPAP and usual care groups for all primary end-points, except for daytime systolic BP. For night-time systolic BP, the mean difference was -6.052 mmHg (95% CI -10.895- -1.208; p=0.016).

Conclusion: These findings suggest a protective effect of CPAP, highlighting the importance of CPAP prescription for this population to control potential increases in BP and possibly prevent the onset of hypertension.

We conducted a randomised, parallel, prospective, controlled trial to evaluate the effect of continuous positive airway pressure (CPAP) on blood pressure (BP) in normotensive individuals with a dipping BP pattern and severe obstructive sleep apnoea (OSA). Participants were randomly assigned to receive either CPAP therapy or usual care for 12 weeks. The primary outcome was the change in ambulatory BP monitoring (ABPM) parameters from baseline to 3 months. Intention-to-treat analysis showed no significant BP changes with CPAP, whereas the usual care group exhibited increases in ABPM parameters, leading to a significant difference in night-time diastolic BP (DBP) between groups. Per-protocol analysis revealed significant differences in all primary end-points except daytime systolic BP (SBP). AHI: apnoea–hypopnoea index. ^#: statistical significance inter-group: *: statistical significance intra-group. Figure partially created with BioRender.com.

FIGURE 1

Patient flowchart. Out of 123 individuals with severe obstructive sleep apnoea (OSA) who were normotensive according to office blood pressure (BP) measurements, 64 met all the inclusion criteria and none of the exclusion criteria. These individuals were randomised to either 3-month continuous positive airway pressure (CPAP) treatment or usual care. After 3 months of follow-up, 60 patients completed the study (30 per group). Eight participants from the CPAP group were excluded from the per-protocol analysis due to insufficient adherence to treatment (<4 h·night⁻¹).

FIGURE 2

Dose–response relationship between adherence to continuous positive airway pressure (CPAP) treatment and changes in ambulatory blood pressure (BP) monitoring parameters during the 3-month follow-up. The p-value threshold defining statistical significance was set at <0.05. DBP: diastolic blood pressure; SBP: systolic blood pressure.