Prevalence and severity of sleep apnea in different stages of chronic kidney disease

Abstract

BACKGROUND: The prevalence and severity of sleep apnea in the non-dialysis chronic kidney disease (CKD) population have not been well characterized. A handful of studies performed to date have yielded highly variable prevalence rates due to cohort heterogeneity and inter-study inconsistencies in sleep apnea definition. This study sought to determine the association of sleep apnea with non-dialysis CKD by recruiting a uniform cohort to undertake overnight polysomnography (PSG). METHODS: 141 male Chinese CKD patients, aged 40 to 60 years old, were recruited to undergo overnight PSG. Height, weight, neck girth, estimated glomerular filtration rate, spot urinary protein excretion and Epworth sleepiness scale (ESS) score were collected at baseline. The prevalence and severity of both sleep apnea and associated nocturnal hypoxemia (NH) were determined across the full spectrum of non-dialysis CKD. RESULTS: The prevalence of sleep apnea (apnea-hypopnea index [AHI] ≥ 15) and NH (Sleep Heart Health Study arbitrary definition) was 35.5% and 10.6% respectively in this study population, which had a mean (± SD) age and BMI of 51.44 ± 6.05 y and 26.05 ± 4.22 kg/m2. The adjusted odds ratio (OR) for sleep apnea by body mass index (BMI) and proteinuria were 1.18 (95% confidence interval [CI] 1.02 - 1.37; P ≤ 0.05) and 2.60 (95% CI 2.56 - 2.61; P ≤ 0.05) respectively. The adjusted OR for median cohort oxygen desaturation index (ODI) by BMI and proteinuria were 1.23 (95% CI 1.05 - 1.45; P ≤ 0.05) and 2.60 (95% 2.56 - 2.61; P ≤ 0.05). However, no significant correlation between prevalence and severity of sleep apnea and NH with progressive renal deterioration was observed. Furthermore, an ESS score above 10 showed no significant mean difference in AHI and ODI when compared to a score below 10. CONCLUSIONS: Sleep apnea is prevalent in the Chinese non-dialysis CKD population and strongly correlated with BMI and proteinuria, but not renal function. The study results also indicate that ESS is an investigative tool that lacks discriminatory power in patients with renal insufficiency. This study supports the need to maintain high clinical vigilance for sleep apnea when attending to CKD patients with significant proteinuria.