Supplementary Material for: Impact of Renin-Angiotensin-Aldosterone System Inhibition on Advanced Chronic Kidney Disease Progression - a Retrospective Observational Study

Introduction: Maintaining renin-angiotensin-aldosterone system inhibition (RAASi) in advanced chronic kidney disease (CKD) to delay CKD progression is still controversial. This is due to potential side effects associated with RAASi, such as a decline in glomerular filtration rate (GFR) and hyperkalemia. This study aims to examine the effect of RAASi on progression of advanced CKD to kidney failure (eGFR <15 ml/min/1.73 m2, CKD stage 5) in a real-life outpatient cohort.

Methods: This single-center retrospective observational study presents data from 954 individuals with advanced CKD (estimated glomerular filtration rate [eGFR] 15-30 ml/min/1.73 m2), comparing 806 RAASi with 511 control intervals over a median follow-up period of 19 months. The endpoint was defined as time to manifestation of kidney failure. Univariate and multivariate time-to-event analysis were performed to assess effects of RAASi on endpoint probabilities.

Results: Univariate time-to-event analysis did not show a significant difference in the median time to kidney failure between RAASi and control intervals (7.6 vs. 7.0 years, p=0.74). Covariate-adjusted multivariate regression models also demonstrated no association between RAASi treatment and progression to kidney failure in patients with advanced CKD (hazard ratio 0.92 [95% CI: 0.67 - 1.23], p=0.63).

Conclusion: RAASi has no significant impact on the time to kidney failure in patients with advanced CKD. Hence, this study supports maintenance of RAASi in advanced CKD, if used for extrarenal indications such as cardiovascular protection.