Intensive BP Control in CKD Improves Survival

Black CKD patients with strict blood pressure control had a 19% lower risk of premature death.
Black CKD patients with strict blood pressure control had a 19% lower risk of premature death.

Intensive blood pressure control may provide protection against early death for black patients with chronic kidney disease (CKD), according to the latest analysis of the African American Study of Kidney Disease (AASK) trial.

In addition, a meta-analysis of pooled results with white patients strengthens evidence for a lower blood pressure target than 140/90 mm Hg, which guidelines currently recommend.

“Overall, our data suggest that [a] strict BP control strategy may lead to a mortality benefit and are consistent with those of SPRINT,” Elaine Ku, MD, of the University of California San Francisco, and colleagues concluded in a paper published online ahead of print in the Journal of the American Society of Nephrology.

SPRINT [Systolic Blood Pressure Intervention Trial] found that patients without diabetes at high cardiovascular risk who reduced systolic blood pressure to less than 120 mm Hg experienced lower rates of death, whether or not they had CKD.

Dr Ku and colleagues recently demonstrated an association between intensive blood pressure control and lower risk of mortality over 2 decades of follow up in the Modification of Diet in Renal Disease (MDRD) trial, involving mostly white patients. For the current analysis of black patients in AASK, the investigators determined the risks of all-cause mortality and end-stage renal disease (ESRD) for 1067 participants over an extended follow-up of more than 14 years. During 1995 to 2001, AASK participants were randomly assigned to usual or strict blood pressure targets (mean arterial pressure 102 to 107 mm Hg or 92 mm Hg or below, respectively).

ESRD developed in 397 patients and 475 patients died during a median follow-up of 14.4 years from 1995 to 2012.

Compared with the group treated to the usual blood pressure target, the strict blood pressure group had a 19% lower adjusted risk of death. In meta-analyses of pooled data from the MDRD and AASK trials, unadjusted results showed a 13% lower risk of death for strict versus usual blood pressure groups. These results contrast with some observational studies that suggested intensive blood pressure control paradoxically increases mortality risk.

According to the investigators, study results reassured that an intensive blood pressure strategy was not associated with significant harm in ESRD or death. Among patients with proteinuria of 1 g/day or more at baseline, a 41% lower risk of ESRD was observed for patients with strict blood pressure control.

“Our findings suggest that, during long-term follow up, strict BP control does not delay the onset of ESRD but may reduce the relative risk of death in CKD,” Dr Ku and colleagues stated.

Importantly, these findings may not be generalizable to all CKD patients. Racial background and cause of CKD differed significantly between AASK and MDRD and potentially influenced results. The study authors also noted that blood pressure treatment occurred during each of the trials. They had no data on blood pressure levels in AASK during the follow up period.

Sources

1.    1. Ku E, Gassman J, Appel LJ, et al. BP Control and Long-Term Risk of ESRD and Mortality. JASN. 2016 Aug 11. doi: 10.1681/ASN.2016030326. [Epub ahead of print]

2. Strict blood pressure control may provide long-term benefits for kidney disease patients. American Society of Nephrology. August 11, 2016. [press release]

 

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