Effect of CPAP therapy on kidney function in patients with chronic kidney disease: a pilot randomized controlled trial

Abstract Background Obstructive sleep apnea (OSA) is common in chronic kidney disease (CKD) and may accelerate a decline in kidney function. It is not clear whether treatment of OSA with continuous positive airway pressure (CPAP) improves kidney function. Research Question Does treatment with CPAP improve kidney function in patients with CKD and co-existing OSA? Study Design and Methods A randomized, controlled, non-blinded, parallel clinical trial was performed on patients with stages 3 and 4 CKD and co-existing OSA comparing the effect of CPAP versus usual care on the estimated glomerular filtration rate (eGFR) and the urine albumin:creatinine ratio (ACR) over 12 months. Results Fifty seven patients were enrolled and 30 were randomized to CPAP. They had moderately severe CKD (eGFR 38.4 ± 1.5 mL/min/1.73 m2) and significant OSA and nocturnal hypoxemia (oxygen desaturation index 23.9 (20.3) events/hour; mean SpO2 89.5 (1.7)%); 60% had baseline albuminuria (ACR > 3 mg/mmol). There was no significant difference between CPAP and usual care in the change in eGFR and ACR over 12 months. Although there was some improvement in eGFR with CPAP therapy in patients with a lower risk of CKD progression, this did not reach statistical significance. Interpretation Although CPAP did not provide additional renal benefits over usual care in all CKD patients, there was some evidence that CPAP slowed the decline in eGFR in CKD patients with a lower risk of CKD progression. These preliminary data support the need and design of larger clinical trials exploring the effect of CPAP on kidney function.