STONE Score Performs Poorly in External Validation Study

The STONE score (see table) is a clinical decision rule designed to categorize risk in patients with suspected nephrolithiasis (NEJM JW Emerg Med Jun 2014 and BMJ 2014; 348:g2191). The authors of the original study found that a high score (10–13 points) could “rule in” renal colic with sufficient confidence that further testing would be unnecessary. Now, researchers evaluated its performance in a secondary analysis of data from a separate multicenter randomized trial that compared initial ultrasound imaging to initial computed tomography (CT) imaging in renal colic patients.

Of 845 patients, 39% had ureteral stones detected by CT. The STONE score was slightly superior to physician gestalt for predicting risk (area under the receiver operatin…