Renoprotective effects of continuous positive airway pressure in chronic kidney disease patients with sleep apnea.

PURPOSE: Chronic kidney disease (CKD) is associated with a high incidence of obstructive sleep apnea (OSA). We assessed the effect of continuous positive airway pressure (CPAP) on renal function in patients with CKD and OSA.

METHODS: In this retrospective cohort study, 42 patients with Stage 3-5 CKD and OSA were stratified into two groups: patients who use CPAP more (average >4 h/night on >70 % of nights) and patients who use CPAP less (average ≤4 h/night on ≤70 % of nights). Median follow-up time was 2.3 (1.6-2.9) years for greater and 2.0 (0.6-3.5) years for lesser CPAP users. Chart reviews were carried out to record clinical characteristics, proteinuria measurements by urine dipstick, and eGFR values calculated by CKD-EPI equations. Univariate analyses were performed using Wilcoxon rank-sum and Kruskal-Wallis tests. Multivariate logistic regression models were applied to assess eGFR decline after CPAP prescription.

RESULTS: Twelve (29 %) of the 42 subjects used CPAP more. Groups were similar with respect to age, body mass index, blood pressure, Charlson Comorbidity Index, and baseline eGFR and proteinuria. The median rate of decline of eGFR was significantly slower at -0.07 mL/min/1.73 m(2)/year (range -30 to 13) in those who used more CPAP compared to those who used it less at -3.15 mL/min/1.73 m(2)/year (range -27 to 7) (p = 0.027).Greater use of CPAP was also associated with a significantly reduced level of proteinuria at 0.15 (range 0.0-3.0) versus 0.70 g/L (range 0.0-3.0) (p = 0.046). Less compliant CPAP users were more likely to have progressive decline of eGFR (decline >3 mL/min/1.73 m(2)/year), with unadjusted OR 5.0 (95 % CI 0.93-26.8) and adjusted OR 8.9 (95 % CI 1.1-72.8), adjusting for CCI and baseline eGFR.

CONCLUSIONS: Compliance to CPAP therapy is associated with a slower rate of progression of CKD in patients with CKD and OSA.