Independent Contributions of Obstructive Sleep Apnea and the Metabolic Syndrome to the Risk of Chronic Kidney Disease

Study Objectives: This retrospective study was conducted to evaluate the associations and interactions among obstructive sleep apnea (OSA), chronic kidney disease (CKD), and metabolic syndrome (MS). Methods: This study included 1,732 subjects (1,482 male and 250 female) in whom OSA was diagnosed by polysomnography. The severity of OSA was defined as mild, moderate, or severe with an apnea-hypopnea index (AHI) score of 5 to < 15, 15 to < 30, and >= 30 events/h, respectively. CKD was defined as an estimated glomerular filtration rate < 60 mL/min/1.73 m(2) or albuminuria. Results: The prevalence of MS was 29.2% (n = 505). One hundred twenty-nine subjects (7.4%) had CKD. In subjects with MS, CKD prevalence increased progressively with OSA severity: 7.4%, 12.5%, and 15.8% in those with mild, moderate, or severe OSA, respectively (P =.025). Each 10-point increment in AHI score was independently associated with a 1.15-fold higher prevalence of CKD [95% confidence interval (CI), 1.036-1.280; P =.009] after adjustment for all individual components of MS. On the contrary, in those without MS, AHI was not associated with increased odds for CKD [odds ratio, 1.054; 95% CI, 0.930-1.195]. Conclusions: The independent association between OSA severity and CKD prevalence was observed only in subjects with MS. Further studies are needed to ascertain if OSA contributes to the development of CKD in subjects with MS.