Validity of STONE Score in Clinical Prediction of Ureteral Stone Disease

Objective: To determine the external validity of STONE score for predicting the probability of ureteral stone in patients presenting in emergency department with suspicion of ureteral stones.

Methods: In this prospective validation study, a total of 134 patients aged above 18 years, and first time arrived in the emergency unit for treatment of flank pain and then referred for the CT scan for suspected ureteral stone in Sandeman Provincial Hospital, Quetta, from 10-June-2018 to 15-Oct-2019 were included. STONE score calculation was done before sending the patient to the CT scan, using the same protocol as defined by Moore et al. Based on STONE score patients classified into the low-risk group (0 to 5), moderate-risk group (5 to 9) and the high-risk group (10 to13). The AUC, sensitivity, specificity and test characteristics were calculated for STONE score.

Results: The mean age was 39.2± 11.2 years, there were 86 (64.17%) men and 48 (35.83%) women. there were 26.8% patients having low-risk score, 52.23% moderate-risk and 21.97% high-risk score. On receiver operating curve (ROC) the area under curve (AUC) of the stone score was 0.75 (95% CI, 0.67 to 0.83), the lower band of AUC 0.67 and upper band 0.83. In high risk STONE score the sensitivity of STONE score was 66.7% and specificity was 75.0%.

Conclusion: Based on our study results, CT scan and ultrasonography are standard diagnostic tools for suspected ureterolithiasis but in emergency unit, use of STONE score to categorize the patient as low risk, moderate-risk and high-risk of ureteral stone can help the physician (clinician) to take decision either there is a need of further investigation or not.