LAUSR

METHODS: Retrospective, observational study in an incident cohort of adult patients with CKD stage 4 or 5 not on dialysis, treated with RAS blockers for at least 6 months prior to the study inclusion. Inclusion criteria were: having at least three consecutive measurements of estimated glomerular filtration rate (eGFR) in a follow-up period> 3 months. Decline in renal function was estimated as the slope of the individual linear regression line of eGFR over follow-up time. Equipotent doses of RAS blockers were normalized for a body weight of 70 kg or a body surface area of 1.73 m2 (END-RAS). For example, the END-RAS in a patient with a body weight of 70 kg receiving a daily dose of enalapril 20 mg or valsartan 160 mg was counted as 1, whereas if he/she received dual RAS blockade with both drugs the END-RAS was then of 2, and so on.Associations of END-RAS or dual RAS blockade with the rate of renal function decline were analysed by unior multivariate linear regression models, accounting for major confounding variables (demographic, co-morbidity, blood pressure, baseline eGFR, serum bicarbonate, proteinuria, and concurrent medication). RESULTS: The study group consisted of 813 patients (mean age 64614 years, 430 males) with a mean eGFR 14.964.2 ml/min/1,73 m2. 729 patients were on RAS blockade monotherapy and 84 on dual RAS blockade. Median END-RAS in the whole group was 0.91 (I.Q. ranges 0.69 1.20). Patients on dual RAS blockade had significantly higher END-RAS than the rest of study patients (1.5260.49 vs. 0.9360.44; p<0.0001). In univariate linear regression, END-RAS blockers were significantly correlated with eGFR decline (beta1⁄4 -0.149; p<0.0001). Patients on dual RAS blockade showed a significantly faster decline of renal function than the rest of the study patients (-6.1965.57 vs. -3.0465.37 ml/min/1,73 m2/year, p<0.0001). By multivariate linear regression, while dual RAS blockade remained independent and significantly associated with faster renal function decline (beta1⁄4 -0.099; p1⁄40.003), END-RAS (normalized either for body weight or surface area) did not reach statistical significance.