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 micromol/L (1.0 mg/dL) to 266 micromol/L (3.0 mg/dL) in women and 106 micromol/L (1.2 mg/dL) to 266 micromol/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.