OBJECTIVES: There are numerous publications on the effects of Ketosteril (a ketoacid-aminoacid oral preparate) both in predialysis and dialysis patients. No data exists, however, to the authors’ knowledge regarding its pharmacoeconomic impact on the treatment of predialysis patients. Our aim was to evaluate the cost-effectiveness of Ketodiet (low/very low protein diet plus Ketosteril) started in stage 3 (GFR 60-30 ml/min) of chronic kidney disease (CKD) versus starting it in stage 4 (GFR 30-15 ml/min) of CKD. A simulation model has been developed to compare the relative costs and health-benefits of the two alternatives. METHODS: Therapeutically effectiveness was clarified on published Hungarian Ketosteril studies (n=171). GFR progression was estimated with a mixed (fixed and random effect) regression analysis of the data for patients treated with and without early Ketosteril for deterministic modeling. 1000 hypothetical patient curves were generated using Bayesian approach to assure the validity of our preliminary hypothesis regarding the expected time to dialysis. Cost analysis based on 80 recent Hungarian CKD patients’ multicenter (n=9) financial resource utilization data. Quality-adjusted life year (QALY) values were assigned to the CKD stages to assess the qualitative and quantitative impact of the two different Ketodiet approaches. A deterministic and probabilistic model was developed for cost-effectiveness analysis. During lifelong modeling costs and outcomes were discounted with official Hungarian rate of 5%. RESULTS: Deterministic modeling showed a cost favour of 6 543,48 € with early (CKD 3) Ketodiet start. Early initiation proved to be also more effective (avg. difference: +0,71 QALY). ICER of the deterministic model (-9 216,17 €/QALY) and 76% of cases in the probabilistic analysis resulted in a dominance with this approach. CONCLUSIONS: Early initiation of the Ketodiet in stage 3 CKD proved to be more advantageous in terms of both healthcare costs and outcomes than starting the treatment in stage 4 CKD.