C-Reactive Protein Levels and the Risk of Incident Cardiovascular and Cerebrovascular Events in Patients with Obstructive Sleep Apnea.

PURPOSE: Patients with obstructive sleep apnea (OSA) are at increased risk of cardiovascular and cerebrovascular disease (CVD) but it is unclear who are at greatest risk. We determined whether the inflammatory marker, C-reactive protein (CRP), could be a useful prognostic biomarker. METHODS: Adult patients referred for polysomnography (PSG) with OSA were studied. Serum CRP levels were measured using ELISA the morning after PSG. Validated CV events within 4 years of PSG were ascertained by linking to provincial research datasets. RESULTS: 155 patients with OSA (AHI ≥ 5/h) had CRP measured. Median age was 53 and median AHI was 21/h. 10 patients (7.1%) suffered at least one event, but rates varied substantially by CRP (0/35 patients in the lowest quartile, and 7/39 in the highest CRP quartile). In the unadjusted analysis, patients in the highest CRP quartile (≥ 2.38 mg/L) were significantly more likely to suffer an event (odds ratio = 9.72 (95% CI 2.43-38.84), p = 0.001). CRP continued to be a significant predictor after controlling for multiple confounders. OSA severity and desaturation were not significantly associated with prospective events. CONCLUSIONS: In this small preliminary study, OSA patients with an elevated CRP were significantly more likely to suffer a CVD event in the 4 years after PSG. Although these findings need to be confirmed in larger prospective cohorts, CRP may be useful in risk stratifying OSA patients to guide therapy or to identify patients that might be most appropriate for clinical trials of CVD prevention.

Predictors of Continuous Positive Airway Pressure Adherence in Patients with Obstructive Sleep Apnea.

Obstructive sleep apnea (OSA) is a common disease which impacts quality of life, mood, cardiovascular morbidity, and mortality. Continuous positive airway pressure (CPAP) is the first-line treatment for patients with moderate to severe OSA. CPAP ameliorates respiratory disturbances, leading to improvements in daytime sleepiness, quality of life, blood pressure, and cognition. However, despite the high efficacy of this device, CPAP adherence is often sub-optimal. Factors including: socio-demographic/economic characteristics, disease severity, psychological factors, and side-effects are thought to affect CPAP adherence in OSA patients. Intervention studies have suggested that augmented support/education, behavioral therapy, telemedicine and technological interventions may improve CPAP adherence. In this paper, we will extensively review the most common factors including age, gender, race/ethnicity, socioeconomic status, smoking status, severity of OSA, severity of OSA symptoms, psychological variables, social support, marital status/bed partner involvement, dry nose and mouth, mask leak, and nasal congestion that may predict CPAP adherence. We will also extensively review interventions that may increase adherence to CPAP.