Proteinuria is associated with sleep apnea in chronic kidney disease

BACKGROUND: The prevalence and severity of sleep apnea (SA) in the chronic kidney disease (CKD) population is not well characterized. Recent studies have yielded highly variable prevalence rates due to cohort heterogeneity and interstudy inconsistencies in defining SA. This study sought to determine the association of SA with CKD by recruiting a uniform cohort to undertake overnight polysomnography (PSG). METHODS: A total of 141 male Chinese CKD patients, ages 40-60 years, underwent overnight PSG to delineate the prevalence and severity of SA and nocturnal hypoxemia (NH). Body mass index (BMI), neck girth, estimated glomerular filtration rate, urinary protein excretion and Epworth sleepiness scale (ESS) score were collected at baseline to determine associative factors. RESULTS: The prevalence rates of SA and NH were 35.5 and 10.6%, respectively, in this study population [mean (±SD) age 51.44 ± 6.05 years; BMI 26.05 ± 4.22 kg/m(2)]. The adjusted odds ratios (ORs) for SA by BMI and proteinuria were 1.18 [95% confidence interval (CI) 1.02, 1.37; P ≤ 0.05] and 1.57 (95% CI 1.12, 2.46; P ≤ 0.05), respectively. The adjusted ORs for the median cohort oxygen desaturation index (ODI) by BMI and proteinuria were 1.23 (95% CI 1.05, 1.45; P ≤ 0.05) and 1.75 (95% CI 1.12, 2.76; P ≤ 0.05). However, no significant correlation between the prevalence and severity of SA and NH with progressive renal deterioration was observed. Furthermore, no significant mean difference in the apnea-hypopnea index and ODI was observed for an ESS above and below 10. CONCLUSIONS: SA is prevalent in CKD patients and strongly correlated with BMI and proteinuria, but not with renal function. The ESS is an investigative tool that lacks discriminatory power in patients with renal insufficiency. Therefore clinical vigilance for SA is paramount when attending to CKD patients with significant proteinuria.