Ms Kelly Loffler and Dr Garun Hamilton
Obstructive sleep apnea (OSA) is a risk factor for developing chronic kidney disease (CKD),
and is common in patients with CKD. Observational studies suggest that treatment of OSA with continuous positive airway pressure (CPAP) may improve or mitigate decline in renal function. In a multi centre study, 200 patients (as a sub-study of the larger SAVE trial) were randomised to receive either CPAP or usual care and followed up for a median of 4.3 years. Decline in renal function and the occurrence of renal adverse events were not significantly different between those who received CPAP therapy and those who did not. Level of CPAP adherence did not influence the findings.
Journal and article title
This study was the first evaluation of the effects of CPAP treatment for OSA on renal function in a
randomised trial. Most subjects had normal or near normal renal function at baseline. Further analysis restricted to individuals (n=22) with more severely reduced baseline eGFR (kidney function stage 3A or worse, <60mL/min/1.73m2), showed comparable rates of decline in eGFR between treatment groups. The result was surprising given that observational studies had suggested a benefit from CPAP. Note also that the study had poor statistical power and the enrolled patients were part of a sub-study of a larger study primarily looking at whether CPAP could reduce cardiovascular risk.
Larger studies are required in a more selected population (e.g. those with pre-existing renal impairment) to determine if there is a benefit from CPAP at reducing the rate of decline of renal function. However, currently there is no evidence to support using CPAP as a means of providing reno-protection.
Obstructive sleep apnoea and Chronic kidney disease