The effect of sleep apnea on all-cause mortality in nondialyzed chronic kidney disease patients

Abstract

BackgroundThe prevalence of sleep-disordered breathing (SDB) in people with chronic kidney disease (CKD) is high. Studies on the effects of sleep apnea (SA) on treatment outcomes have been mostly focused on dialyzed CKD or renal transplant patients. Studies on the effects of SA on all-cause mortality in nondialyzed CKD patients are scarce. MethodsWe enrolled and followed up all adults who were referred for diagnostic testing for sleep apnea between March 2007 and July 2014, had undergone polysomnography, and whose records of serum creatinine levels were available. The outcomes were all-cause mortality and renal outcome. ResultsA total of 1454 participants were included in the study. Of these, 103 patients (7.08%) had CKD and 38 patients (2.61%) died. CKD was associated with central sleep apnea (CSA) (odds ratio [OR] = 5.158 [95% confidence interval {CI} = 1.992–13.355], p = 0.001) and severe SDB (OR = 1.737 [1.119–2.695], p = 0.014). CSA was a risk factor for all-cause mortality in nondialyzed subjects (adjusted hazard ratio [HR]= <4.250 [CI = 1.560–11.573], p = 0.005), whereas CSA was found to be a stronger risk factor for all-cause mortality in subjects with CKD (adjusted HR = 40.728 [CI = 4.765–348.117], p = 0.001). Mixed sleep apnea was related to rapid decline of renal function in nondialyzed subjects (adjusted HR = 1.932 [CI = 1.183–3.155], p = 0.009), whereas, OSA was (adjusted HR = 3.315 [CI = 1.188–9.248], p = 0.022) in CKD subjects. ConclusionIn nondialyzed patients, CKD was each associated with central sleep apnea (CSA) and severe SDB. CSA was an independent risk factor for all-cause mortality, and was a more evident mortality risk in CKD patients than in non-CKD participants. Rapid decline of renal function may play a role in the mortality of CKD patients associated with SA.