Sleep Apnea, Cardiovascular Morbidity and Death, and Peritoneal Dialysis
Sleep Apnea, Cardiovascular Morbidity and Death, and Peritoneal Dialysis
Sleep apnea syndrome is increasingly recognized in peritoneal dialysis patients; however, its prognostic implication in this population is unknown. To study this, we prospectively followed the clinical outcome of 93 peritoneal dialysis patients with baseline polysomnography. Of these, 51 were diagnosed with the syndrome defined by an apnea–hypopnea index (AHI) of at least 15 per hour. During a median follow-up of 41 months, there were 30 deaths, of which 17 were due to cardiovascular causes. Kaplan–Meier analysis for the entire follow-up period indicated that patients with sleep apnea at baseline had significantly higher all-cause and cardiovascular mortality during follow-up than those without. Minimal nocturnal saturation and desaturation indices were predictors of mortality and cardiovascular events at univariate analysis. Multivariable Cox regression analysis identified significant sleep apnea syndrome at baseline as an independent predictor of increased all-cause mortality independent of age, male gender, and diabetic status. Further, an absolute increase in the AHI was associated with an incremental risk of cardiovascular events. Thus, sleep apnea syndrome, detected at the start of peritoneal dialysis, is a novel risk predictor for subsequent mortality and cardiovascular events.
Sleep disturbances are highly prevalent among dialysis patients compared with the general population. Among the various sleep disturbances, sleep apnea is being increasingly recognized in dialysis patients. Although sleep-disordered breathing occurred in 2–4% of the middle-aged Chinese population, its prevalence is uniformly over 50% among Chinese subjects on peritoneal dialysis as gauged by self-reported questionnaires or by the more objective method of overnight polysomnographic measurement. Unruh et al. recently reported that patients on hemodialysis had a fourfold increase in prevalence of sleep-disordered breathing and nocturnal hypoxemia even after adjusting for cardiovascular morbidity and diabetic status, compared with participants from the Sleep Heart Health Study matched for age, gender, body mass index, and race, indicating that the pathophysiology of sleep apnea is uniquely associated with the development of chronic renal failure. Several studies have addressed the effect and importance of sleep apnea on quality of life of peritoneal dialysis patients and showed that sleep problems severely affect their general health and psychosocial well-being. However, it remains unknown whether sleep apnea in peritoneal dialysis patients is a risk factor for mortality and morbidity, in particular cardiovascular events as occurs with the nondialysis population.
We have embarked on the 'Sleep apnea in PD patients' program since 2001 to study sleep apnea in Chinese peritoneal dialysis patients, focusing on the pathogenetic mechanisms of sleep apnea during uremia. We prospectively collected baseline polysomnographic data on a cohort of Chinese peritoneal dialysis patients soon after the commencement of peritoneal dialysis and followed their clinical outcome longitudinally. In this study, we hypothesize that the severity of sleep apnea, reflected by the apnea-hypopnea index (AHI) or the number of apneic or hypopneic events per hour of sleep, is a polysomnographic marker that predicts all-cause mortality and cardiovascular events in the chronic peritoneal dialysis population.
Abstract and Introduction
Abstract
Sleep apnea syndrome is increasingly recognized in peritoneal dialysis patients; however, its prognostic implication in this population is unknown. To study this, we prospectively followed the clinical outcome of 93 peritoneal dialysis patients with baseline polysomnography. Of these, 51 were diagnosed with the syndrome defined by an apnea–hypopnea index (AHI) of at least 15 per hour. During a median follow-up of 41 months, there were 30 deaths, of which 17 were due to cardiovascular causes. Kaplan–Meier analysis for the entire follow-up period indicated that patients with sleep apnea at baseline had significantly higher all-cause and cardiovascular mortality during follow-up than those without. Minimal nocturnal saturation and desaturation indices were predictors of mortality and cardiovascular events at univariate analysis. Multivariable Cox regression analysis identified significant sleep apnea syndrome at baseline as an independent predictor of increased all-cause mortality independent of age, male gender, and diabetic status. Further, an absolute increase in the AHI was associated with an incremental risk of cardiovascular events. Thus, sleep apnea syndrome, detected at the start of peritoneal dialysis, is a novel risk predictor for subsequent mortality and cardiovascular events.
Introduction
Sleep disturbances are highly prevalent among dialysis patients compared with the general population. Among the various sleep disturbances, sleep apnea is being increasingly recognized in dialysis patients. Although sleep-disordered breathing occurred in 2–4% of the middle-aged Chinese population, its prevalence is uniformly over 50% among Chinese subjects on peritoneal dialysis as gauged by self-reported questionnaires or by the more objective method of overnight polysomnographic measurement. Unruh et al. recently reported that patients on hemodialysis had a fourfold increase in prevalence of sleep-disordered breathing and nocturnal hypoxemia even after adjusting for cardiovascular morbidity and diabetic status, compared with participants from the Sleep Heart Health Study matched for age, gender, body mass index, and race, indicating that the pathophysiology of sleep apnea is uniquely associated with the development of chronic renal failure. Several studies have addressed the effect and importance of sleep apnea on quality of life of peritoneal dialysis patients and showed that sleep problems severely affect their general health and psychosocial well-being. However, it remains unknown whether sleep apnea in peritoneal dialysis patients is a risk factor for mortality and morbidity, in particular cardiovascular events as occurs with the nondialysis population.
We have embarked on the 'Sleep apnea in PD patients' program since 2001 to study sleep apnea in Chinese peritoneal dialysis patients, focusing on the pathogenetic mechanisms of sleep apnea during uremia. We prospectively collected baseline polysomnographic data on a cohort of Chinese peritoneal dialysis patients soon after the commencement of peritoneal dialysis and followed their clinical outcome longitudinally. In this study, we hypothesize that the severity of sleep apnea, reflected by the apnea-hypopnea index (AHI) or the number of apneic or hypopneic events per hour of sleep, is a polysomnographic marker that predicts all-cause mortality and cardiovascular events in the chronic peritoneal dialysis population.
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