Baseline predictors of renal disease progression in the African American Study of Hypertension and Kidney Disease

Abstract

Patients with chronic kidney disease have an increased risk for progression to ESRD. The purpose of this study was to examine factors that predict increased risk for adverse renal outcomes. Cox regression was performed to assess the potential of 38 baseline risk factors to predict the clinical renal composite outcome of 50% or 25-ml/min per 1.73 m(2) GFR decline or ESRD among 1094 black patients with hypertensive nephrosclerosis (GFR 20 to 65 ml/min per 1.73 m(2)). Patients were trial participants who had been randomly assigned to one of two BP goals and to one of three antihypertensive regimens and followed for a range of 3 to 6.4 yr. In unadjusted and adjusted analyses, baseline proteinuria was consistently associated with an increased risk for adverse renal outcomes, even at low levels of proteinuria. The relationship of proteinuria with adverse renal outcomes also was evident in analyses that were stratified by level of GFR, which itself was associated with adverse renal outcomes but only at levels <40 ml/min. Other factors that were significantly associated with increased renal events after adjustment for baseline GFR, age, and gender, both with and without adjustment for baseline proteinuria, included serum creatinine, urea nitrogen, and phosphorus. In black patients with hypertensive nephrosclerosis, increased proteinuria, reduced GFR, and elevated levels of serum creatinine, urea nitrogen and phosphorus were directly associated with adverse clinical renal events. These findings identify a subset of this high-risk population that might benefit from even more aggressive treatment.

Figure 1

Joint association of the renal composite (GFR event or ESRD) with baseline proteinuria and baseline GFR. Shown are hazard ratios of the renal composite (GFR event or ESRD) for the designated combinations of levels of baseline proteinuria (expressed as baseline urine protein/creatinine ratio) and baseline GFR, adjusting for age, gender, and randomized treatment groups. Both baseline factors are strongly predictive of the occurrence of a GFR event or ESRD after controlling for the other.

Figure 2

Association of composite outcomes with baseline factors, with and without adjustment for baseline proteinuria. Shown are the hazard ratios (with 95% confidence intervals [CI]) of two composite outcomes that are associated with 1-SD increases in the indicated baseline factors: (1) GFR event or ESRD and (2) GFR event, ESRD, or death. Results are provided both without adjustment for baseline proteinuria (CI indicated with solid lines) and then with adjustment for baseline proteinuria (CI indicated with dashed lines). All analyses are adjusted for age, gender, mean baseline GFR, and randomized treatment groups. S., serum; ECG, electrocardiogram; LVH, left ventricular hypertrophy; U., urine.