Sleep apnea, coronary artery disease, and antioxidant status in hemodialysis patients

Background: It recently was suggested that sleep apnea syndrome (SAS) is associated with the cardiovascular complications and outcomes seen in patients with end-stage renal disease (ESRD). This study investigates the association of SAS with coronary artery disease and antioxidant status in patients with ESRD. Methods: Twenty-six hemodialysis patients underwent overnight polysomnography to evaluate sleep parameters. We performed multirow spiral computed tomography to derive coronary artery calcification (CAC) scores as an indicator of the severity of coronary artery disease and measured predialysis serum total antioxidant status (TAS) as a marker of antioxidant defenses. Results: Nine of 26 patients had normal to mild SAS with an apnea-hypopnea index (AHI) less than 15, 9 patients had moderate SAS with an AHI of 15 to 30, and the remaining 8 patients had severe SAS with an AHI greater than 30. AHI and oxygen desaturation index (ODI) were strongly interrelated (r = 0.754; P < 0.001). CAC severity was associated with SAS severity: median CAC scores Increased (P = 0.009) with increasing AHI category. However, values for TAS were not significantly different among the 3 AHI categories. CAC score also correlated positively (r = 0.564; P = 0.003) with ODI, and TAS correlated negatively (r = -0.539; P = 0.005) with ODI. Conclusion: These results suggest that frequent oxygen desaturation triggered by SAS is associated with severe coronary artery disease and decreased antioxidant status in patients with ESRD. However, conclusions from this study should be drawn with caution because of its methodological limitations (cross-sectional design, heterogeneity of study population, and small number of patients).