Introduction: The RENAAL (Reduction of Endpoints in Non-insulin dependent diabetes with the Angiotensin II Antagonist Losartan) study demonstrated that, in hypertensive patients with type 2 diabetes mellitus and nephropathy, treatment with losartan plus conventional antihypertensive therapy (CT) reduced the relative risk of end-stage renal disease (ESRD) by 29% versus placebo over the time span of the study (mean patient follow-up of 3.4 years). The objective of this study was to project the effect of losartan compared with placebo on the lifetime incidence of ESRD and associated costs (from a US healthcare system perspective).
Methods: To estimate lifetime incidence of ESRD, we used a competing risks method to account for the risk of death without ESRD. We estimated the cost (US dollars, year 2002 values) associated with ESRD by combining the cumulative incidence of ESRD with the lifetime cost associated with ESRD. Total cost was estimated as the sum of the cost associated with ESRD, the cost of losartan study therapy and other costs (non-ESRD/non-losartan) expected for patients with type 2 diabetes. Survival was estimated by weighting the life expectancies with and without ESRD by the cumulative risk of ESRD. Costs and outcomes were discounted by 3% per annum.
Results: We projected a lower lifetime incidence of ESRD for losartan patients (66%) compared with placebo patients (83%). This reduction in ESRD resulted in a decrease in cost associated with ESRD of US dollars 31,803 per patient and a gain of 0.99 life-years per patient (0.70 discounted). After accounting for the cost of losartan and the additional cost associated with greater survival, we projected that treatment with losartan would result in a lifetime net saving of US dollars 24,632 per patient.
Conclusion: Treatment with losartan plus CT in patients with type 2 diabetes and nephropathy reduced the within-trial incidence of ESRD and is projected to result in lifetime reductions in ESRD and associated costs, and increased survival, versus placebo.