Reducing systolic blood pressure is critical to slowing the progression of diabetic renal disease, researchers stated at the 35th annual meeting of the American Society of Nephrology (ASN) last week. >Blood pressure reduction is a good approach to treating Type 2 diabetics with nephropathy, even in patients with severe disease, said Dr. Samuel Blumenthal, MD, of Veterans Administration, Milwaukee, Wisconsin, United States.
Dr. Blumenthal said previous data from the Irbesartan Diabetic Nephropathy Trial (IDNT) — which compared irbesartan, placebo and the calcium channel blocker amlodipine — showed the news is "very good, as far as the kidney is concerned", because it is the level of achieved systolic blood pressure that matter, not baseline values (New Engl J Med 2001 Sep 20;345(12):851-60).
Essentially, the data show that "the kidney has no past history", he said. "At any point, reduction in blood pressure is beneficial and will reduce risk."
IDNT — a prospective, randomized, double-blind study of 1,715 patients — showed that treatment with the angiotensin II receptor blocker irbesartan resulted in a 33 percent lower risk of doubling the serum creatinine concentration than with placebo (p=0.003) and 37 percent lower than with amlodipine (p<0.001), independent of achieved blood pressure.
In their new study, Dr. Blumenthal and colleagues assessed the effects of blood pressure control on 1,626 patients who had blood pressure measurements at six months after beginning the study.
The level of systolic blood pressure is strongly correlated with the risk of progression to a renal event, Dr. Blumenthal said, either a doubling of serum creatinine or end-stage renal disease.
Bu the baseline pressure is much less predictive than the pressure achieved at 12 months, he said. The relative risk reduction of a 10-mm Hg difference in systolic pressure at baseline was 5 percent; the comparable figure for the 12-month pressure was 16 percent. Diastolic pressure was not correlated to risk of progression, either at baseline or at 12 months.
After 54 weeks of treatment and follow-up, patients in the two lowest quartiles of systolic blood pressure at 12 months (less than 132 mm Hg and between 132 and 141 mm Hg) had nearly the same risk of a renal event, Dr. Blumenthal said. In both those groups, the risk was about 30 per cent. In the two highest quartiles (between 142 and 153 mm Hg and greater than 154 mm Hg) the risk was almost doubled, to about 55 percent in both groups.
"Tight control of [systolic] blood pressure is an essential part of the management of the patient with diabetic nephropathy to prevent renal complications," Dr. Blumenthal said.