To pay or not to pay? A decision and cost-utility analysis of angiotensin-converting-enzyme inhibitor therapy for diabetic nephropathy

Background: Angiotensin-converting-enzyme (ACE) inhibitor therapy can signi ficantly delay the progression of diabetic nephropathy to end-stage renal f ailure (ESRF). The main obstacle to successful compliance with this therapy is the cost to the patients. The authors performed a cost-utility analysis from the government's perspective to see whether the province or territory should pay for ACE inhibitors for type I diabetic nephropathy on the assum ption that cost is a major barrier to compliance with this important therap y. Methods: A decision analysis tree was created to demonstrate the progressio n of type diabetes with macroproteinuria from the point of prescription of ACE inhibitor therapy through to ESRF management, with a 21-year follow-up. Drug compliance, cost of ESRF treatment, utilities and survival data were taken from Canadian sources and used in the cost-utility analysis. One-way and two-way sensitivity analyses were performed to test the robustness of t he findings. Results: Compared with a no-payment strategy, provincial payment of ACE inh ibitor therapy was found to be highly cost-effective: it resulted in an inc rease of 0.147 in the number of quality-adjusted life-years (QALYs) and an annual cost savings of $849 per patient. The sensitivity analyses indicated that the cost-effectiveness depends on compliance, effect of benefit and t he cost of drug therapy. Changes in the compliance rate from 67% to 51% cou ld result in a swing in cost-effectiveness from a savings of $899 to an exp enditure of more than $1 million per additional QALY. A 50% reduction in th e cost of ACE inhibitors would result in a cost savings of $299 per additio nal QALY with compliance rates as low as 58% in the provincial payment stra tegy. Interpretation: Provincial coverage of ACE inhibitor therapy for type I dia betes with macroproteinuria improves patient outcomes, with a decrease in c ost for ESRF services.