Nocturnal intermittent hypoxia and short sleep duration are independently associated with elevated C-reactive protein levels in patients with coronary artery disease

Background Sleep-disordered breathing (SDB) or short sleep duration and coronary artery disease (CAD) are related, yet, the prevalence of SDB and short sleep duration as well as their mechanism remain unknown. Enhanced vascular inflammation is also implicated as one of the pathophysiologic mechanisms in CAD. The aims of this study were to evaluate the prevalence of patients with SDB and short sleep duration, and to examine their relationship with serum C-reactive protein (CRP) level in CAD patients. Methods and results We evaluated 161 CAD patients who underwent percutaneous coronary intervention, using nocturnal pulse oximetry, a non-invasive screening method for nocturnal intermittent hypoxia. Based on three percent oxygen desaturation index (3% ODI), the patients were divided into nocturnal intermittent hypoxia (3% ODI ≥ 15; n = 45) and control groups (3% ODI < 15, n = 116). The nocturnal intermittent hypoxia group had higher body mass index and serum CRP level compared with the control group. Short sleep duration (<6 h, n = 45) was also associated with increased CRP level compared with the control group (≥6 h, n = 116). In multiple regression analysis, nocturnal intermittent hypoxia (β = 0.332, 95% confidence interval [CI] 0.102–0.562, P = 0.005) and short sleep duration (β = 0.311, 95% CI 0.097–0.526, P = 0.005) were both independent determinants for log serum CRP level. Conclusions Nocturnal intermittent hypoxia and short sleep duration were independently associated with elevated serum CRP level in CAD patients, suggesting that both SDB and sleep shortage are associated with enhanced inflammation in CAD patients. SDB and sleep duration may be important modifiable factors in the clinical management of patients with CAD.