Overweight explains the increased red blood cell aggregation in patients with obstructive sleep apnea.

Sleep apnea patients and obese subjects are overexposed to cardiovascular diseases. These two health conditions may be associated with hemorheological alterations which could increase the cardiovascular risk. The present study investigated the hemorheological characteristics in patients with overweight and/or sleep apnea to identify the main predictor of red blood cell (RBC) abnormalities in sleep apnea patients. Ninety-seven patients were subjected to one night sleep polygraphy to determine their sleep apnea status. Body mass index (BMI) and the apnea/hypopnea index (AHI) were determined for categorization of obesity and sleep apnea status. Blood was sampled for hematocrit, blood viscosity, RBC deformability, aggregation and disaggregation threshold measurements. BMI and AHI were positively associated and were both positively associated with RBC aggregation. Analyses of covariance and multiple regression analyses revealed that BMI was more predictive of RBC aggregation than AHI. No association of BMI classes and AHI classes with RBC deformability or blood viscosity was observed. This study shows that increased RBC aggregation in sleep apnea patients is caused by overweight. Therapies to improve blood rheology in sleep apnea patients, and therefore reduce the risk for cardiovascular disorders, should focus on weight-loss.