External validation of risk stratification strategy in the use of renal ultrasonography in the evaluation of acute kidney injury.

BACKGROUND: Per the American College of Radiology Appropriateness Criteria, renal ultrasound is the most appropriate imaging examination to evaluate patients with acute kidney injury. However, recent studies suggest that renal ultrasound may be more selectively performed, which could lead to reductions in the use of medical imaging.

OBJECTIVE: Evaluate a published risk stratification prediction model (the Licurse model) for using renal ultrasound in hospitalized patients with acute kidney injury.

DESIGN: Prospective, observational cohort study.

SETTING: A 793-bed, quaternary care, academic hospital.

PATIENTS: All adult hospitalized patients who underwent renal ultrasound for the indication of acute kidney injury.

INTERVENTION/EXPOSURE: None.

MEASUREMENTS: Primary outcome was rate of hydronephrosis diagnosed on ultrasound. Secondary outcome was rate of hydronephrosis resulting in urologic intervention.

RESULTS: Of 778 patients who underwent renal ultrasonography to evaluate acute kidney injury, hydronephrosis was present in 106 (13.6%); urologic intervention was performed in 23 patients (3.0%). The Licurse model had sensitivity of 91.3% (95% confidence interval [CI]: 73.2%-97.6%) for urologic intervention and 93.4% (95% CI: 87.2%-96.8%) for hydronephrosis, respectively. Specificity was low for urologic intervention (23.0% [95% CI: 20.2-26.2]) and hydronephrosis (25.1% [95% CI: 22.0-28.6]). We estimated that for 22.6% of patients, hydronephrosis could be ruled out based on clinical predictors.

CONCLUSIONS: We found that the Licurse renal ultrasonography risk stratification model was sufficiently accurate in classifying patients at risk for ureteral obstruction among hospitalized patients with acute kidney injury. Journal of Hospital Medicine 2016;11:763-767. © 2016 Society of Hospital Medicine.