Cost-Effectiveness of Irbesartan 300 mg Given Early Versus Late in Patients with Hypertension and a History of Type 2 Diabetes and Renal Disease: A Canadian Perspective

Abstract

Background: The Irbesartan in Reduction of Microalbuminuria trial and the Irbesartan in Diabetic Nephropathy Trial found that irbesartan is renoprotective in patients having hypertension with type 2 diabetes. Objective: The objective of this study was to assess whether treatment with irbesartan is cost-effective in Canada relative to conventional care in this patient population and whether it is more cost-effective to treat patients early rather than later in the development of renal disease from the perspective of the Canadian health and social care system. Methods: The analysis compared 3 alternative strategies for the management of hypertension in patients with type 2 diabetes and early renal disease: (1) conventional hypertensive treatment excluding the use of angiotensin II receptor antagonists (AIIRAs); (2) the early addition of irbesartan (an AIIRA) to conventional treatment; and (3) the late addition of irbesartan to conventional treatment. A Markov model was used to simulate the progression of renal disease (microalbuminuria to death) in hypertensive patients with type 2 diabetes over a 25-year time horizon. Transition probabilities were derived from the 2 randomized controlled trials. A cost-effectiveness analysis was conducted with outcome measured in life-years gained (LYGs). Results: The early addition of irbesartan during microalbuminuria was cost-saving and more effective than both delaying irbesartan treatment until advanced overt nephropathy (AON) (0.45 LYG, Can $54,100 saved) and conventional antihypertensive use (0.62 LYG, $68,400 saved). This was due to the increased drug costs associated with the use of irbesartan being offset by savings arising from delays in the development of overt nephropathy and the subsequent delay to end-stage renal disease (ESRD). Sensitivity analyses confirmed the robustness of the study results. Conclusions: The early use of irbesartan for patients with hypertension and type 2 diabetes who have yet to develop overt nephropathy is both more effective and less costly than delaying irbesartan treatment until AON and conventional antihypertensive use. Analysis suggests that the earlier irbesartan is added to conventional antihypertensive treatment, the greater the delays in the onset of ESRD and the overall savings in health care resource utilization from the perspective of the Canadian health and social care system.