Effects of Continuous Positive Airway Pressure for Hypertension in Patients with Obstructive Sleep Apnoea: A Structured Narrative Review of Randomised Controlled Trials

Introduction: Obstructive sleep apnoea usually co-occurs with hypertension and is managed using various therapeutic modalities. Continuous positive airway pressure (CPAP) appears to be one of the promising interventions. This review aims to narratively assess its effectiveness by comparing its effect with usual and standard care. Method: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines were consulted to enhance transparency in reporting the search and selection process; however, this review does not meet the full criteria for a systematic review because screening, data extraction, and synthesis were not conducted according to full systematic review methodology. Five electronic databases (APA PsycINFO, Web of Science, Embase, AMED, and Medline) were searched. Only randomised controlled trials were considered eligible and were assessed for risk of bias using the Physiotherapy Evidence Database (PEDro) scale. Effect sizes were calculated using an online tool developed by the Campbell Collaboration, George Mason University, version 27 November 2023. They were interpreted as trivial (<0.1), small (0.1–0.3), moderate (0.3–0.5), or large (>0.5) effects, respectively. Results: This study includes 2944 subjects, 63.3% of whom were male. Their ages range from 23 to 69.7 years. The effect sizes for systolic blood pressure ranged from small to large (d = −0.2, 95% CI −0.69 to 0.28, to d = 0.7, 95% CI −0.15 to 1.55), and for diastolic blood pressure from d = 0.1, 95% CI −0.3 to 0.57, to d = 1.4, 95% CI −0.97 to 2.08 magnitude of effects was observed for both systolic and diastolic blood pressure at different times of the day. Standard care, such as medication and telemedicine, does not confer superior effects over usual care. This intervention showed evidence of sustained effects; however, further evidence is required. Conclusions: CPAP may be effective for both systolic and diastolic blood pressure in patients with obstructive sleep apnoea at different times of day. Its effect may be sustained. The effective dose of CPAP on hypertension remains unclear. Future studies should consider using a more robust design, such as a systematic review and meta-analysis, to obtain pooled estimates rather than individual effect sizes.