Doppler ultrasound, renal resistive index both predictive of AKI

The power Doppler ultrasound (PDU) and renal resistive index (RRI) methods of predicting subsequent acute kidney injury (AKI) have comparable performances, reports a recent meta-analysis.

Drawing from the databases of the Cochrane library, Embase, and PubMed, researchers retrieved 23 prospective studies with a total of 2,400 patients. Outcome parameters for both PDU and RRI were sensitivity, specificity, diagnostic odds ratio (DOR), and positive (PLR) and negative likelihood ratios (NLR). Receiver operating characteristic curve analysis was also performed.

Pooled analysis revealed that RRI had a sensitivity and specificity of 0.76 and 0.79, respectively, while corresponding values for PDU were 0.64 and 0.90. Both methods had statistically comparable sensitivities (ratio, 1.19, 95 percent confidence interval [CI], 0.93–1.52; p=0.165), while RRI was slightly but significantly worse in terms of specificity (ratio, 0.88, 95 percent CI, 0.78–0.98; p=0.028) for AKI prediction.

Both methods were statistically comparable in terms of PLR (ratio, 0.55, 95 percent CI, 0.22–1.39; p=0.204), NLR (ratio, 0.77, 95 percent CI, 0.46–1.32; p=0.331), DOR (ratio, 0.72, 95 percent CI, 0.14–3.61; p=0.692), and area under the curve (ratio, 0.97, 95 percent CI, 0.92–1.01; p=0.201).

Of note, the researchers reported a significant publication bias for both RRI and PDU, as well as strong heterogeneity of evidence.

“Further large-scale prospective studies should be performed to [directly compare] the prediction performance of RRI and PDU for subsequent AKI risk in patients with various medical conditions. Moreover, the prediction model for AKI risk should be updated [to contain indices] from ultrasound using machine learning approach,” the researchers said.