Performance of renal Doppler to predict the occurrence of acute kidney injury in patients without acute kidney injury at admission

This study aimed at evaluating the performance of Doppler-based resistive index (RI) and semi-quantitative evaluation of renal perfusion using color-Doppler (SQP) to predict de novo AKI in the subgroup of critically ill patients without AKI at admission.This study is an ancillary analysis of a prospective multicenter cohort study. Consecutive ICU patients requiring mechanical ventilation were included. Renal Doppler was performed at ICU admission. The diagnostic performance of RI and SQP to predict de novo AKI at day 3 was evaluated.Among the 371 patients of the prospective cohort, 118 without AKI at study inclusion were included. Thirty-four patients (29%) developed an AKI. Neither RI (0.64 UI [0.57-0.70] vs 0.67 [0.62-0.70] in no AKI and de novo AKI group respectively, p = 0.177) nor SQP (2 [2, 3] vs 2 [1-3] in no AKI and de novo AKI group respectively, p = 0.061) were associated with AKI occurrence. Overall performance in predicting de novo AKI was null to poor with area under ROC curve of respectively 0.60 (95% CI 0.49-0.65) and 0.58 (95% CI 0.47-0.60) for RI and SQP. Similar results were obtained after adjustment for confounders.These results confirm the poor performance of Doppler-based indices in predicting renal prognosis of ICU patients.