CPAP decreases blood pressure in patients with OSA, uncontrolled hypertension
Key takeaways:
- For changes in office blood pressure from baseline to 6 months, researchers found significant drops among those using CPAP vs. placebo.
- Twenty-four-hour BP control was reached by more CPAP patients.
Among patients with moderate to severe obstructive sleep apnea and uncontrolled hypertension, some measures of blood pressure fell significantly with 6-month CPAP use, according to data published in Annals of the American Thoracic Society.
CPAP use also had an impact on 24-hour ambulatory BP monitoring control, according to researchers.
“Despite the modest effects of CPAP on peripheral and central BP, the MORPHEOS trial showed that 6 months of CPAP use doubled 24-[hour] BP control as compared to placebo,” Geraldo Lorenzi-Filho, MD, PhD, of the department of cardio-pulmonology at the University of São Paulo, and colleagues wrote. “This is an important message that may be significant to the way we clinically approach patients with OSA and uncontrolled [hypertension].”
In the multicenter, randomized controlled MORPHEOS trial, Lorenzi-Filho and colleagues assessed 123 patients with moderate to severe OSA and uncontrolled hypertension on regular anti-hypertensive treatment to determine how CPAP impacts three BP-related outcomes vs. placebo in the form of nasal dilator strips at 6 months.
A patient was classified with uncontrolled hypertension if they had at least one abnormal parameter in ambulatory BP monitoring after 1-month of pill count and at least 80% adherence to medication.
In this study population, 59 patients received CPAP, and the remaining 64 patients received placebo. A greater proportion of patients in the placebo group had adherence, defined as at least 80% in this treatment, vs. patients in the CPAP group, in which adherence was defined as at least 4 hours per night (98.3% vs. 81.7%).
When analyzing changes in office BP from baseline to 6 months, researchers reported significant decreases among those using CPAP vs. placebo in both office systolic BP (–10 mmHg vs. –4 mmHg) and diastolic BP (–7 mmHg vs. –1 mmHg).
Switching to measures of central BP, patients using CPAP also had significantly lower central diastolic BP vs. patients using placebo (–6 mmHg vs. –3 mmHg; P = .029), according to the study. Change in central systolic BP at 6 months did not significantly differ between the two groups (CPAP, –10 mmHg vs. placebo, –6 mmHg), but researchers noted that the change from baseline to 6 months in the CPAP group was significant (139 mmHg to 130 mmHg; P = .006).
Similar to above, although not achieving significance when comparing the two groups, researchers found that patients using CPAP vs. placebo had slightly greater changes in several parameters of ambulatory BP monitoring at the 6-month mark, including 24-hour diastolic BP (–4 mmHg vs. –2 mmHg), 24-hour mean BP (–4 mmHg vs. –3 mmHg), daytime diastolic BP (–4 mmHg vs. –2 mmHg) and daytime mean BP (–4 mmHg vs. –3 mmHg).
Notably, nighttime heart rate was one ambulatory BP monitoring measure that did significantly differ between the groups (change from baseline to 6 months: CPAP, –1 rpm vs. placebo, +2 rpm; P = .021).
Another measure that did significantly differ between those using CPAP and those using placebo was 24-hour ambulatory BP monitoring control (systolic BP less than 130 mmHg and diastolic BP less than 80 mmHg). This measure was reached by 40.7% of the CPAP group and 20% of the placebo group (P = .024).
“Future studies are necessary to investigate the long-term effects of CPAP on BP control and on cardiovascular events in patients with uncontrolled [hypertension],” Lorenzi-Filho and colleagues wrote.
Perspective
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In December 2022, the Agency for Healthcare Research and Quality (AHRQ) released its report, “Long-term health outcomes in obstructive sleep apnea: A systematic review of comparative studies evaluating positive airway pressure and the validity of breathing measures as surrogate outcomes.” Its conclusion shook the field of sleep medicine. “Randomized control trials (RCTs) do not provide evidence that CPAP prescription affects long-term, clinically important outcomes.” One of the task force’s more sobering findings was that RCTs did not show that CPAP helped high BP compared with no CPAP.
Along comes MORPHEOS to the rescue! The multicenter MORPHEOS RCT out of Brazil evaluated the effects of CPAP vs. placebo (nasal dilator strips) on uncontrolled hypertension in patients with moderate to severe OSA. After a run-in period, patients were followed for 6 months and had blood pressure measurements taken at the office as well as by central BP and ambulatory BP monitoring, which were the co-primary endpoints. The results showed that CPAP lowered all blood pressure measures better than placebo, with office systolic BP (delta, –10 ± 16 mmHg; P < .001), diastolic BP (delta = –7 ± 12 mmHg; P = .001) and central diastolic BP reaching statistical significance.
One of the biggest strengths of the MORPHEOS study was that it identified and treated hypertension during the run-in period, including monitoring anti-hypertensive medication use through reconciliation and pill counting. CPAP was able to further improve blood pressure control beyond medication alone over the next 6 months. Improvements in blood pressure were significantly better in patients who slept at least 5 hours on their CPAP machine (mean time of CPAP use, 5:46 ± 0:11 hours/night; compliance, 81.7%).
Exclusion criteria for this Brazilian study included age greater than 65 years and BMI greater than 40 kg/m2. Also noteworthy was that despite both groups having severe OSA (overall AHI, 42.2; low O2, 76%), the placebo group was not provided treatment other than with nasal dilator strips, a study design that may have been harder to get through institutional review boards in the United States.
Usage of ambulatory BP monitoring to determine how sleep duration on CPAP impacts dipping and morning blood pressure spikes might make for an interesting future study.
Reference:
Long-term health outcomes in obstructive sleep apnea: A systematic review of comparative studies evaluating positive airway pressure and the validity of breathing measures as surrogate outcomes. https://www.ahrq.gov/sites/default/files/wysiwyg/research/findings/ta/sleep-apnea/sleep-apnea-report.pdf. Published Dec. 1, 2022. Accessed Feb. 24, 2025.
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