Interrelationship among Obstructive Sleep Apnea, Renal Function and Survival: A Cohort Study

Abstract

<jats:p>Previous studies showed a bidirectional relationship between renal function decline and obstructive sleep apnea (OSA) syndrome. Continuous Positive Airway Pressure (C-PAP) treatment was shown to preserve the kidney function in OSA patients. This study aims to investigate the progression of long-term renal function in OSA patients treated with different PAP strategies (patients were divided into two groups, fixed C-PAP or other PAP—automatic and bilevel pressure). Comorbidities and 10-years survival were also evaluated. We performed a retrospective, observational, single-center, cohort study, including the first 40 consecutive patients enrolled from 2009 in the Respiratory disease Unit at the Vercelli University Hospital database. The patient inclusion criteria were: age ≥ 18 years with OSA syndrome according to AASM (American Academy of Sleep Medicine) guidelines. Creatinine serum levels (mg/dL) and the estimated Glomerular Filtration Rate (eGFR, mL/min calculated by CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration equation)) were measured at 3 different time points: at baseline, 3 years and 8 years after PAP treatment. The Kaplan–Meier survival curves stratified according to PAP treatment and compliance have been reported together with log-rank test estimation. In our study, we found a significant creatinine serum level reduction after 3 years of fixed C-PAP treatment (p value = 0.006) when compared to baseline values. However, we observed that the long-term C-PAP benefit was not significant (p value = 0.060). Our data confirmed the progressive renal function decline in OSA patients, especially in those using other-PAP treatments; nevertheless, OSA treatment with a fixed C-PAP device has shown, in the short term, a significant improvement in renal function. By contrast, in our study, long-term benefits after 8 years are not been demonstrated probably because of the lack of compliance of the patients and the aging effect.</jats:p>

Pre-Dialytic SpO2 Measured with a Wearable Device as a Predictor of Mortality in Patients with OSA and Chronic Kidney Disease

“…Indeed, there is a growing body of research that links OSA to arrhythmias and sudden cardiac death [25]. Intriguingly, a bidirectional relationship interplays between chronic kidney disease and OSA; and vice versa, continuous, supplemental oxygen therapy with continuous, positive airway pressure improves the renal function in OSA patients [16]. To investigate it further, we conducted the current study.…”

“…After adjusting above significant risk factors in the multivariable Cox regression model, however, OSA lost the predictive power for all-cause and CV mortality (Table 5). In view of this, OSA and lower levels of SpO2 may share the common pathway in the pathogenesis of CV death that OSA patients require more frequent screening for SpO2 levels [16,17]. We, therefore, applied 95% as the cut-off value for abnormal pre-dialytic SpO2 in the secondary analysis.…”

Comorbid Insomnia and Obstructive Sleep Apnea (COMISA): Current Concepts of Patient Management

“…OSA is the most common kind of sleep apnea characterized by upper airway collapse during sleep with repeated episodes of apneas and hypopneas leading to oxygen desaturations; it is related to many other medical conditions such as congestive heart failure, hypertension, stroke, arrhythmia and decline in renal function [94] that may have a negative prognostic effect on long-term survival as demonstrated in our unit in a retrospective observational cohort study recently conducted [95]. At the same time, OSA can be associated with very frequent sleep disorder comorbidities, i.e., insomnia.…”

Bidirectional relationships of comorbidity with obstructive sleep apnoea

“…Another uncontrolled observational study reported a significant reduction in serum creatinine and increase in eGFR in males with AHI >20 after 3 months of CPAP [87]. A longer follow-up study again showed positive short term benefits but, after 8 years, patients with higher AHI had higher serum creatinine levels, despite CPAP treatment [74]. An RCT of patients with Stage 3 and 4 CKD showed no statistically significant difference in eGFR between CPAP and usual care over a 1 year follow-up, while demonstrating some improvement in renal function in those at a lower risk of CKD progression [88].…”

“…End-stage renal disease (ESRD) can also lead to worsening of OSA. It is increasingly recognised that OSA increases the risk of kidney injury and is associated with progressive decline in renal function [74].…”