Prediction of acute kidney injury: the ratio of renal resistive index to semiquantitative power Doppler ultrasound score—a better predictor?: A prospective observational study

This study aimed to explore the diagnostic performance of the ratio of renal resistive index (RRI) to semiquantitative power Doppler ultrasound (PDU) score in predicting acute kidney injury (AKI) 3 in critically ill patients. This study was a prospective, observational study that included 101 critically ill patients. RRI and semiquantitative PDU score were measured within 6 hours following admission to the intensive care unit (ICU). The ratio of RRI to PDU (RRI/PDU) was calculated as follows: RRI / PDU. If PDU score was 0, the RRI/PDU was 1. Meanwhile, AKI was defined according to the Kidney Disease Improving Global Outcomes criteria. Median RRI/PDU was 0.234 (0.190, 0.335) in patients with AKI 0–2 and 0.636 (0.411, 0.738) in patients with AKI 3 (P < .001). As assessed by the area under the receiver operator characteristic curves (AUC), RRI/PDU performed best in diagnosing AKI 3 [AUC = 0.935 (95% CI: 0.868–0.974)]. Optimal cuto for RRI/PDU was > 0.37, and the sensitivity and specificity were 90.5% and 90.0%, respectively. In 93 patients, except for 8 patients with a PDU score of 0, the AUC of RRI/PDU [0.938 (95% CI: 0.868–0.977)] was superior to the PDU score (0.905 [95% CI: 0.826–0.956], P = .133), RRI [0.782 (95% CI: 0.684–0.861), P = .016], serum creatinine [0.801 (95% CI: 0.705–0.877), P = .017], or 6 hours AKI stage (0.876 [95% CI: 0.791–0.935], P = .110) in predicting AKI 3 on D5. In our study, RRI, PDU score, RRI/PDU, and 6 hours AKI stage were useful in predicting AKI 3. Furthermore, RRI/PDU may be a better predictor of AKI 3.