The cost-effectiveness of losartan in type 2 diabetics with nephropathy in Switzerland - an analysis of the RENAAL study

BACKGROUND: The prevalence and incidence of diabetic nephropathy with endstage renal disease (ESRD) have increased globally over recent decades. Diabetic nephropathy with ESRD for type 2 diabetes mellitus (DM) now has to be recognized as a growing public health problem. Several studies have found that angiotensin-II receptor antagonists have a renoprotective effect in type 2 diabetics with diabetic nephropathy, independently of their antihypertensive effects. These studies have shown a prevention of the progression of nephropathy to ESRD, or a slowing of that progression. The RENAAL study demonstrated the clinical benefits of losartan in patients with DM type 2 and advanced diabetic nephropathy. AIM: The aim of this cost-effectiveness analysis of the RENAAL study was to evaluate the effect of losartan compared to a placebo from a Swiss third party payer perspective. METHODS: Using a decision analytic model, we evaluated the cost-effectiveness for losartan on the basis of the RENAAL study. A follow-up period of 3.5 years was used. Effectiveness was defined as the number of ESRD days saved. We valued haemodialysis, peritoneal dialysis and kidney transplantation. A weighted mean value was calculated for the daily costs of an ESRD (CHF 215.05). In the case of renal transplantation follow-on costs, resource utilization was determined through a telephone-based interview with 5 of the 6 Swiss transplantation centres. Expert consensus methodology was used to determine the proportion of health care resource utilization in type 2 diabetics. The percentage of patients receiving each of the 3 treatment alternatives was derived from a cross-sectional national study conceived for this purpose. The daily costs for haemodialysis and peritoneal dialysis were derived from figures provided by insurers. The costs of treatment with losartan were calculated on the basis of an average daily dose of losartan over a period of 3.5 years. RESULTS: Over a period of 3.5 years, losartan significantly reduced the number of ESRD days of type 2 diabetics with nephropathy by an average of 33.6 days (95% CI: 10.9, 56.3) compared to the placebo. This reduction in the number of ESRD days resulted in ESRD-associated cost savings of CHF 7,226 per patient over a period of 3.5 years (the ESRD-associated costs savings increased to CHF 10,086 per patient after 4 years). If the average costs per patient for treatment with losartan for the same period (CHF 3,142) are subtracted from the CHF 7,226 then the reduction in ESRD days yields net cost savings of CHF 4,084 per patient over 3.5 years. The univariate sensitivity analyses for the variables ESRD daily costs and percentage distribution of the 3 treatment modalities always yielded net cost savings. DISCUSSION: This evaluation revealed net cost savings of CHF 4,084 (F 2,687) for patients with diabetic nephropathy and type 2 diabetes when given 50 to 100 mg losartan once daily over a period of 3.5 years compared to placebo. The net cost savings that administration of losartan yielded are of considerable importance given that the annual costs of diabetic nephropathy with ESRD in type 2 diabetics in Switzerland are approximately CHF 46 million. On the basis of the scientific evidence currently available, the use of losartan to prevent the advance of diabetic nephropathy is worthwhile from both a clinical and economic perspective.