Association of Renal Resistive Index with Target Organ Damage in Essential Hypertension

Background: The renal resistive index (RI) measured using Doppler ultrasonography has been used as a diagnostic tool in the daily work-up of kidney diseases. A better understanding of its relationship with preclinical organ damage may help in determining overall cardiovascular risk in hypertensive patients.

Methods: We evaluated the association between RI and the presence and degree of target organ damage (TOD) in 288 (130 male) essential hypertensive patients. RI, carotid intima-media thickness (IMT), and left ventricular (LV) mass index were assessed by ultrasound scan. Albuminuria was measured as the albumin-to-creatinine ratio (ACR) in three consecutive first morning urine samples.

Results: In univariate analysis, patients with TOD showed significantly higher RI as compared with those without TOD (presence vs. absence of carotid wall thickening, LV hypertrophy, and albuminuria, P < 0.01, respectively). The severity of each TOD increased progressively from the lower to the upper RI tertile. Multiple logistic regression analysis found that each standard deviation increase in RI gave a 47% higher odds of having LV hypertrophy, and a 70% higher odds of having albuminuria (P < 0.05, respectively). The occurrence of at least two signs of TOD also significantly increased in parallel with elevation of RI (odds ratio (OR): 1.89 for 1 s.d. increase, P < 0.01).

Conclusions: These results suggest that increased RI may be a marker of subclinical TOD in patients with essential hypertension.