Resistive index as a predictor of acute kidney injury caused by an angiotensin converting enzyme inhibitor or angiotensin II receptor blocker in chronic kidney disease patients

BACKGROUND Angiotensin converting enzyme (ACE) inhibitor and angiotensin receptor blocker (ARB) may induce acute kidney injury (AKI). The aim of this study was to evaluate the role of the resistive index (RI), which reflects renal artery resistance on renal duplex ultrasonography, as a predictor of AKI in chronic kidney disease (CKD) patients who are prescribed an ACE inhibitor or ARB. METHODS We screened 105 CKD patients evaluated with renal duplex ultrasonography from 2008 to 2012. We excluded patients not treated with ACE inhibitor or ARB and diagnosed with renal artery stenosis. Finally, we retrospectively analyzed the medical records of 54 patients. AKI was defined as increased serum creatinine by >30% compared with baseline after starting ACE inhibitor or ARB treatment. RESULTS The mean age of the patients was 60.5±13.0 years, serum creatinine level was 1.85±0.85 mg/dL and 22.2% of the patients had AKI after the use of an ACE inhibitor or ARB. The RI (P=0.006) and the percentages of patients with diabetes (P=0.008) and using diuretics (P=0.046) were higher in the AKI group. The area under the receiver operating characteristics curve for the prediction of AKI was 0.736 (95% confidence interval=0.587-0.885, P=0.013), and RI≥0.80 predicted AKI with 83.3% sensitivity and 61.9% specificity. In the multivariate analysis, RI≥0.80 was an independent prognostic factor [Exp (B)=8.03, 95% confidence interval=1.14-56.74, P=0.037] for AKI. CONCLUSION RI≥0.80 on the renal duplex ultrasonography may be a helpful predictor for AKI in CKD patients who are prescribed an ACE inhibitor or ARB.