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21-03-2013 | General practice | Article

Adverse kidney disease outcomes linked to blood pressure in African Americans


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medwireNews: African-American individuals who have chronic kidney disease (CKD) are at a greater risk for mortality the more varied their systolic blood pressure (BP) is, report researchers.

In a large, longitudinal analysis of African Americans with hypertensive nephrosclerosis, those with the greatest systolic BP visit-to-visit variability ([SBV] the variation in BP that is captured at sequential office visits) had significantly increased rates of overall mortality and cardiovascular mortality compared with those who had the least SBV, report Ciaran McMullan, from Brigham and Women's Hospital in Boston, Massachusetts, USA, and team.

"This is the largest study to date to examine the association of SBV with outcomes in patients who have established CKD, and is the only such study in blacks," says the team.

The study included 908 participants who were going through the trial phase of the African American Study of Kidney Disease, with at least 1 year of BP data available and who were followed up for 3.0-6.4 years. The patients had a baseline glomerular filtration rate (GFR) of 20-65 mL/min per 1.73 m2 and a mean SBV of 13.6 mmHg during visits occurring between 3 and 12 months after randomization to antihypertensive therapies.

As reported in the Clinical Journal of the American Society of Nephrology, 64 patients died by the end of the follow-up period and 133 had a cardiovascular (CV) event (CV death, CV revascularization, nonfatal myocardial infarction, hospitalization for heart failure, or stroke), of which 22 cases were CV deaths.

The researchers report that the incidences of the clinical outcomes all-cause mortality, cardiovascular mortality, cardiovascular events, and renal events (composite comprising end-stage renal disease, a reduction in GFR ≥50% from baseline, a GFR decline from baseline of ≥25 mL/min per 1.73 m2, or death) were significantly higher across increasing tertiles of SBV.

Multivariate analysis showed that all-cause mortality was almost threefold higher among those in the highest tertile for SBV, compared with those in the lowest tertile. Similarly, there was a significant fivefold increase in risk for CV mortality for those in the highest versus lowest tertile of SBV.

For the composite CV and renal endpoints, greater SBV was associated with an increased risk in unadjusted models, but not adjusted analyses, reports the team.

"Further studies are required to discover modifiers of SBV, and to test whether modification of SBV can reduce both overall and cardiovascular mortality," concludes the team.

By Sally Robertson, medwireNews Reporter

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