Cardiovascular Outcomes in the Irbesartan Diabetic Nephropathy Trial of Patients with Type 2 Diabetes and Overt Nephropathy

Background: Patients with diabetes have increased risk for adverse cardiovascular events. Angiotensin-converting enzyme inhibitors are protective in type 1 diabetes. However, no definitive studies have examined the use of angiotensin-receptor blockers in patients with type 2 diabetes and overt nephropathy. The primary outcomes of the Irbesartan Diabetic Nephropathy Trial were doubling of serum creatinine levels, end-stage renal disease, and death from any cause. Objective: To compare rates of cardiovascular events among patients with type 2 diabetic nephropathy who received conventional antihypertensive therapy with an angiotensin-receptor blocker (irbesartan) or a calcium-channel blocker (amlodipine), or placebo. Design: Randomized double-blind, placebo-controlled trial with a median follow-up of 2.6 years. A time event analysis was used. Setting: 209 centers in the Americas, Europe, Israel, and Australasia. Participants: 1715 adults with type 2 diabetic nephropathy and hypertension; serum creatinine levels of 89 μmol/L (1.0 mg/dL) to 266 μmol/L (3.0 mg/dL) in women and 106 μmol/L (1.2 mg/dL) to 266 μmol/L (3.0 mg/dL) in men; and urinary protein excretion rates of at least 900 mg/d. Intervention: Treatment with irbesartan, amlodipine, or placebo. Measurements: Time to cardiovascular death, myocardial infarction, congestive heart failure, strokes, and coronary revascularization. Results: The three groups were not statistically different in the composite of cardiovascular events. Among the components of the composite, there was a trend toward a decrease in strokes in patients receiving amlodipine versus those receiving placebo (hazard ratio, 0.65 [95% CI, 0.35 to 1.22]; P= 0.18). Likewise, patients receiving amlodipine had a significantly lower rate of myocardial infarction when compared with placebo recipients (hazard ratio, 0.58 [CI, 0.37 to 0.92]; P= 0.02). In contrast, patients receiving irbesartan had a significantly lower incidence of congestive heart failure when compared with placebo recipients (hazard ratio, 0.72 [CI, 0.52 to 1.00]; P = 0.048) or amlodipine recipients (hazard ratio, 0.65 [CI, 0.48 to 0.87]; P = 0.004). Conclusion: The composite cardiovascular event rate did not differ in patients with type 2 diabetes and overt nephropathy treated with irbesartan, amlodipine, or placebo in addition to conventional antihypertensive therapy.