Correlation between Renal Resistive Index and Estimated Glomerular Filtration Rate in Patients with Hypertension

Abstract

Introduction Renal resistive index (RRI) is a marker of flow resistance in renal parenchymal vessels. Kidneys may appear normal when imaged by ultrasound in early stages of chronic kidney disease (CKD). Several studies have shown that cortical echogenicity is not an objective way to assess CKD. Thus, if RRI correlates with estimated glomerular filtration rate (eGFR), it could serve as an additional predictor and objective measure of CKD. Currently to our knowledge studies assessing correlation between eGFR and RRI are lacking. Objective We sought to assess the correlation between RRI and eGFR. Methods In the 1-year study period, 874 abdominal Doppler examinations were performed in an accredited vascular laboratory by a single technologist. Analysis was performed for 310 Doppler results that met inclusion criteria. Serum creatinine was obtained from the electronic chart, and eGFR was calculated with the use of the abbreviated Modification of Diet in Renal Disease Study Group GFR equation. Results Statistical analysis using Pearson's correlation coefficient demonstrated a significant negative correlation between RRI and eGFR (r = −0.285, p < 0.01). Conclusion Our study serves as a pilot assessing correlation between eGFR and RRI. This correlation could serve as an early objective indicator of renal impairment as kidneys may appear normal by ultrasound in early stages of CKD.