ABSTRACT
PURPOSE: The objective of this study was to model patient outcomes and treatment costs over a 5-year horizon time for renal transplant patients comparing twice-daily tacrolimus to once-daily extended-release tacrolimus as a primary immunosuppressive agent. METHODS: We constructed a stochastic state-transition model to simulate the incidence of acute rejection, graft loss and subsequent return to dialysis, retransplantation, and mortality among transplanted patients, as well as their associated costs. The two immunosuppressive treatment arms analyzed were twice-daily tacrolimus plus mycophenolate mofetil (MMF) and once-daily extended-release tacrolimus plus MMF. Estimates for the current rate of adherence to twice-daily medication, as well as the improvement in adherence expected in a once-daily medication, were taken from literature reviews. Sensitivities around these estimates were analyzed. Cost data for medical procedures and hospitalization were obtained from Medicare and the United States Renal Data System (USRDS). Medicare ASP prices from July 2006 were used to price pharmaceutical products. Once-daily extended-release tacrolimus was assumed to have the same daily cost as twice-daily tacrolimus. RESULTS: Patient outcomes included a decrease in acute rejections, increase in graft survival, and a corresponding decrease in number of patients on dialysis. Using once-daily extended-release tacrolimus increased graft survival at 5 years from 63.0% to 69.1% an absolute increase of 6.1 percentage points. Overall cost savings averaged $9411 per patient over the 5-year treatment using a 5% discount rate. Total costs, including initial transplantation, were $238,144 for twice-daily tacrolimus and $228,734 for once-daily extended-release tacrolimus.
