AASK: Aggressive blood pressure control has little effect on progression of kidney disease in African American patients

According to the results of an extended follow-up of the African American Study of Kidney Disease and Hypertension (AASK), long-term reduction of blood pressure to a lower goal than the standard demonstrates no significant effect on the progression of chronic kidney disease (CKD) in nondiabetic hypertensive patients, except in patients with baseline urinary protein/creatinine ratio >0.22, said Jackson Wright, MD, professor of medicine and director of the hypertension program at Case Western Reserve University, Cleveland. These results were presented at the 23rd Annual Scientific Meeting of the American Society of Hypertension, New Orleans, May 14–17, 2008.

More than 10 years of follow-up data for AASK participants are now available. The main results from the initial (trial) phase (N=1,094), published in 2002, demonstrated that the angiotensin-converting enzyme (ACE) inhibitor ramipril was more effective than the calcium-channel blocker amlodipine and the beta-blocker metoprolol as initial therapy in slowing the progression of hypertensive renal disease. The largest difference in renal outcomes among therapies was observed in patients with a urinary protein/creatinine ratio >0.22 (representing approximately 300 mg/d of protein). There was no difference in progression of renal disease between participants randomized to a lower goal for mean arterial pressure (<92 mmHg) compared with those randomized to a goal of 102 to 107 mmHg, regardless of urinary protein/creatinine ratio.

The second phase (cohort phase; N=691) of AASK was completed in June 2007. At the end of the initial phase, all participants received recommended blood pressure therapy with ramipril (or an angiotensin receptor blocker [ARB]) to achieve a blood pressure goal <130/80 mmHg. As in the first phase, the primary outcome was a composite of a doubling of serum creatinine from the trial’s baseline, progression to end-stage renal disease, or death.

“In the cohort phase, a trend toward a persistence of the benefit with the ACE inhibitor was seen,” said Dr Wright. As in the first phase, however, there was no difference on the primary outcome between patients randomized to the usual or lower blood pressure goals.

Dr Wright said that “a possible long-term benefit of initial assignment to the lower blood pressure goal was seen in patients with baseline urinary protein/creatinine ratio >0.22.” Among these patients, the incidence of the primary outcome was significantly reduced versus those randomized to the usual goal (HR=0.72; P=.0076).

“An interaction test of blood pressure goal with baseline proteinuria was very significant (P=.015) but was not significant in the drug therapy comparison,” said Dr Wright.