Association of Sleep-Disordered Breathing/Sleep apnea With Renal Outcome and All-Cause Mortality: A Sleep Clinic Cohort Study

Abstract

Background: The prevalence of sleep-disordered breathing (SDB)/sleep apnea (SA) is high. SDB/SA and chronic kidney disease (CKD) share common risk factors, pathophysiological mechanisms, and are commonly comorbid with diabetes mellitus (DM), hypertension (HTN), and body mass index (BMI) in the overweight/obese range (≥ 23 kg/m2). Previous research has mostly focused on the correlations between SDB/SA and renal function. The present study investigated the effects of SDB/SA on renal function decline in patients with DM, HTN, CKD, and in overweight/obese individuals. The rapid decline of the estimated glomerular filtration rate (eGFR

RDeG) has been reported to be a risk factor for all-cause mortality (ACM)

therefore, the impact of SDB/SA on ACM was also investigated. Methods: We conducted a longitudinal analysis of a sleep clinic cohort. In analysis I, we enrolled and followed all adult subjects who were referred for diagnostic testing for SDB/SA between March 2007 and July 2014, had undergone polysomnography, and whose test records for serum creatinine levels were available. In analysis II, Patients with predominate central sleep apnea (CSA) are commonly comorbid with heart disease or cerebrovascular disease and may have higher rates of mortality, therefore, they were excluded from the analysis I cohort. The measured outcomes of both analyses were ACM and RDeG. Results: A total of 1,454 participants were included in analysis I. Of these, 103 patients (7.08%) had CKD and 38 patients (2.61%) died during the study. CKD was associated with severe SDB [odds ratio (OR) = 1.74 (1.12-2.70), p < 0.05]. CSA was associated with RDeG in the cohort [adjusted hazard ratio (HR) = 2.451 (1.193-5.037), p = 0.015], DM subjects [adjusted HR = 2.951 (1.032-8.434), p = 0.043], HTN subjects [adjusted HR = 2.524 (1.146-5.558), p = 0.022] and overweight/obese subjects [adjusted HR = 3.207 (1.528-6.73), p = 0.002]. Obstructive sleep apnea (OSA) was a risk factor for RDeG in CKD patients [adjusted HR = 3.242 (1.235-8.51), p = 0.017]. CSA was a risk factor for ACM in the cohort [adjusted HR = 4.642 (1.749-12.322), p = 0.002], DM [adjusted HR = 10.285 (2.285-46.281), p = 0.002], HTN [adjusted HR = 5.797 (1.558-21.574), p = 0.009], CKD [adjusted HR = 11.093 (2.671-46.069), p = 0.001], and overweight/obese subjects [adjusted HR = 7.317 (2.535-21.124), p < 0.001]. In analysis II, the respiratory disturbance index (RDI) was found to be a risk factor for RDeG in the cohort [adjusted HR = 1.007 (1-1.015), p = 0.047], CKD subjects [adjusted HR = 1.038 (1.001-1.075), p = 0.043], and overweight/obese subjects [adjusted HR= 1.011 (1.004-1.019), p = 0.005]. The obstructive apnea index (AI)-to-respiratory disturbance index (RDI) ratio predicted the risk of death in the cohort [adjusted HR = 1.015 (1.002-1.028), p = 0.033], DM subjects [adjusted HR = 1.053 (1.01-1.099), p = 0.016], and HTN subjects [adjusted HR = 1.036 (1.008-1.064), p = 0.01], whereas RDI was a risk factor for ACM in CKD subjects [adjusted HR = 1.063 (1.005-1.123), p = 0.032]. Conclusion: In the present study, CKD was associated with severe SDB (RDI ≥ 30/h). SDB/SA was a predictor/risk factor for the rapid decline of eGFR in the cohort and in patients with CKD or who were overweight/obese. SDB/SA also predicted the risk of death in the cohort and in patients with HTN/DM/CKD. A multi-step approach that uses a variety of therapeutic modalities is recommended for SDB/SA in DM/HTN/CKD patients to reduce the mortality risk.