Is renoprotection by angiotensin receptor blocker dependent on blood pressure?: the Saitama Medical School, Albuminuria Reduction in Diabetics with Valsartan (STAR) study

Abstract

To explore the effects of various antihypertensive regimes on microalbuminuria, an angiotensin II receptor blocker (ARB), valsartan, was substituted for or added to treatment with a calcium channel blocker (CCB). After a 6-month CCB baseline period, 28 Japanese hypertensive patients with incipient diabetic nephropathy (defined as a urinary albumin excretion [UAE] of 30-300 mg/g creatinine), were assigned to two groups according to their blood pressure (BP) levels: in patients with a BP of more than 130/85 mmHg (n=17), valsartan was added to the CCB (Group A), while in patients with a BP <130/85 mmHg, valsartan alone was given (Group B: n=11) for 12 months. UAE was determined before and at 3, 6 and 12 months after the initiation of ARB. Although the initial BP was significantly higher in Group A (150/83 mmHg) than Group B (127/77 mmHg), BP was decreased to 141/78 mmHg in Group A and slightly, but not significantly, increased to 130/82 mmHg in Group B. In both groups, UAE was significantly decreased after ARB treatment (to 89% of the basal value in Group A and to 40.5% of the basal value in Group B) and did not differ each other and the amount of decrease did not differ significantly between the two groups. These results suggest that combination therapy with an ARB and CCB is very effective in lowering BP and UAE in cases in which BP is not well controlled, while, even in patients with a sufficient BP control of <130/85 mmHg, the use of ARB singly resulted in a significant decrease in UAE without a further decrease in BP, implying that the ARB had a renoprotective action independent of changes in BP.