Resistive index predicts renal prognosis in chronic kidney disease

While the clinical validity of Doppler ultrasonography in renal parenchymal disease is still controversial, we have previously reported that the resistive index (RI) and the atrophic index (AI) could estimate tubulointerstitial injury. We aimed to determine whether these indices could estimate renal prognosis in chronic kidney disease (CKD).

We performed a 2-year follow-up study with an observational cohort of 311 CKD patients. The patients were examined by Doppler ultrasonography to calculate RI and AI to be calculated. Glomerular filtration rate (GFR) was estimated with the abbreviated MDRD study equation every 6 months.

When we divided the patients into three groups by the RI value of 0.65 and 0.70, there were significant differences in the decrease in GFR among the three groups at 24 months. Kaplan-Meier analysis also showed a significant difference among the three groups in the survival rate of worsening renal function, which was defined as a decrease in GFR of at least 20 mL/min 1.73 m(2) or the need for long-term dialysis therapy until the end of the 2-year follow-up. Cox proportional-hazard analysis identified overt proteinuria (> or =1.0 g/g creatinine), high RI (>0.70) and high systolic blood pressure (> or =140 mmHg) as independent predictors of worsening renal function. In contrast, AI was of no significance in evaluating renal prognosis in CKD.

This study suggested that RI, and proteinuria and hypertension were independent risk factors for the progression of CKD.