Effect of Continuous Positive Airway Pressure on Cardiovascular Biomarkers: The Sleep Apnea Stress Randomized Controlled Trial

Abstract

Background: Although existing research highlights the relationship of OSA and cardiovascular disease, the effect of OSA treatment on cardiovascular biomarkers remains unclear. We evaluated the effect of OSA treatment on oxidative stress/inflammation measures.

Methods: We conducted a parallel, randomized controlled trial in moderate to severe OSA (apnea-hypopnea index ≥ 15) patients to examine effects of 2-month CPAP vs sham-CPAP on the primary outcome of oxidative stress/inflammation (F2-isoprostanes: ng/mg) and myeloperoxidase: pmol/L) and secondary oxidative stress measures. Exploratory secondary analyses included vascular and systemic inflammation markers. Linear models adjusted for baseline values examined effect of CPAP on biomarker change (least squares means, 95% CI) including secondary stratified analyses examining CPAP adherence and degree of hypoxia.

Results: Of 153 participants, 76 were randomized to CPAP and 77 to sham-CPAP. In an intent-to-treat analyses, no significant change was observed in the sham and CPAP groups respectively: F2-isoprostanes (-0.02 [-0.12 to 0.10] vs -0.08 [-0.18 to 0.03]) or myeloperoxidase (-3.33 [-17.02 to 10.37] vs -5.15 [-18.65 to 8.35]), nor other oxidative markers; findings that persisted in analyses stratified by adherence and hypoxia. Exploratory analyses revealed percentage reduction of soluble IL-6 receptor (ng/mL) levels (-0.04 [-0.08 to -0.01] vs 0.02 [-0.02 to 0.06], P = .019) and augmentation index (%) (-6.49 [-9.32 to -3.65] vs 0.44 [-2.22 to 3.10], P < .001) with CPAP compared with sham, respectively.

Conclusions: In moderate to severe OSA, 2-month CPAP vs sham did not reduce oxidative stress despite consideration of a broad range of measures, positive airway pressure adherence, and hypoxia burden. These findings suggest that nonoxidative stress pathways primarily modulate OSA-related cardiovascular consequences.

Trial registration: ClinicalTrials.govNCT00607893.

Keywords: CPAP; inflammation; obstructive sleep apnea.