The Correlation between Red Blood Cell Distribution Width Levels with the Severity of Obstructive Sleep Apnea and Carotid Intima Media Thickness

BACKGROUND Obstructive sleep apnea syndrome (OSAS) is characterized by repetitive collapse of the upper airway during sleep. Red blood cell distribution width (RDW) increases platelet activation and has been reported as an independent predictor of adverse outcomes in the general population and is believed to be associated with cardiovascular morbidity and mortality. We evaluated RDW, mean platelet volume (MPV), and platelet distribution width (PDW) as a severity index in OSAS and the relationship between carotid intima media thickness and pulmonary hypertension. MATERIAL/METHODS The study population consisted of 99 patients who were admitted to the sleep laboratory. Based on the apnea-hypopnea index, patients were grouped into 3 OSAS severity categories. Morning blood samples were withdrawn from patients after a 12-hour fasting period. MPV, PDW, and RDW were measured in a blood sample. Bilateral common carotid arteries of the patients were scanned. RESULTS Ninety-nine patients--73 with OSAS and 26 simple snoring control cases--were included. Mean values of MPV, PDW, and RDW were similar in patients compared to simple snoring subjects in the control group (p=0.162, p=0.656, p=0.091). RDW showed an inverse correlation with mean desaturation and lowest desaturation (p<0.01). Body mass index, apnea-hypopnea index, pulmonary artery pressure, and desaturation time under 90% were positively correlated with RDW (p<0.05). MPV, PDW, and carotid intima media thickness had no correlation with any other parameters. CONCLUSIONS The study showed a positive relationship between RDW and the apnea-hypopnea index and systolic pulmonary hypertension in patients with OSAS.