Fixed But Not Autoadjusting Positive Airway Pressure Attenuates the Time-dependent Decline in Glomerular Filtration Rate in Patients With OSA

BACKGROUND: The impact of treating OSA on renal function decline is controversial. Previous studies usually included small samples and did not consider specific effects of different CPAP modalities. The aim of this study was to evaluate the respective influence of fixed and autoadjusting CPAP modes on estimated glomerular filtration rate (eGFR) in a large sample of patients derived from the prospective European Sleep Apnea Database cohort. METHODS: In patients of the European Sleep Apnea Database, eGFR prior to and after follow-up was calculated by using the Chronic Kidney Disease-Epidemiology Collaboration equation. Three study groups were investigated: untreated patients (n = 144), patients receiving fixed CPAP (fCPAP) (n = 1,178), and patients on autoadjusting CPAP (APAP) (n = 485). RESULTS: In the whole sample, eGFR decreased over time. The rate of eGFR decline was significantly higher in the subgroup with eGFR above median (91.42 mL/min/1.73 m(2)) at baseline (P < .0001 for effect of baseline eGFR). This decline was attenuated or absent (P < .0001 for effect of treatment) in the subgroup of patients with OSA treated by using fCPAP. A follow-up duration exceeding the median (541 days) was associated with eGFR decline in the untreated and APAP groups but not in the fCPAP group (P < .0001 by two-way ANOVA for interaction between treatment and follow-up length). In multiple regression analysis, eGFR decline was accentuated by advanced age, female sex, cardiac failure, higher baseline eGFR, and longer follow-up duration, whereas there was a protective effect of fCPAP. CONCLUSIONS: fCPAP but not APAP may prevent eGFR decline in OSA.