Association of renal resistive index with target organ damage in essential hypertension

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.

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.

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).

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