Pro-inflammatory markers in patients with obstructive sleep apnea and the effect of Continuous Positive Airway Pressure therapy

To evaluate the association of obstructive sleep apnea (OSA) with high-sensitivity C-reactive protein (CRP) and fibrinogen levels and to assess the effect of short-term therapy using continuous positive airway pressure (CPAP). A prospective, open-label, controlled trial was conducted among clinically referred patients at risk for OSA undergoing diagnostic polysomnography (PSG). After PSG, the patients were divided into 3 groups: OSA treatment group (TG) (n=21), untreated OSA group (UOG) (n=19), and non-OSA healthy control group (HCG) (n=24). CRP and fibrinogen levels were measured at baseline and one month after treatment. Repeated-measures (RM) ANOVA and ANCOVA were used to compare changes in CRP and fibrinogen levels among the three groups by analyzing between-subject and within-subject effects as functions of time and adjusting for significant covariates. At baseline, OSA subjects had significantly higher CRP [t(52.37)=-2.46, p=0.02)] and fibrinogen levels [t(57)=-2.00, p=0.05)] than HCG subjects. No significant differences in CRP levels [(F(2,58)=2.29, p=0.11)] or fibrinogen levels [(F(2, 58)=1.28, p=0.29)] emerged between TG and HCG subjects after adjusting for the pretest levels. CPAP therapy for one month does not affect CRP and fibrinogen levels among moderate-to-severe OSA patients. However, OSA is associated with elevated levels of these inflammatory biomarkers.