Is STONE score a useful tool for limiting the use computed tomography in the patients suspected ureter stone? - A single-center retrospective study

Lee, Dong Geun; Kim, Hyung Bin; Cho, Young Mo; Bae, Byung Kwan; Wang, Il Jae; Yeom, Seok Ran; Park, Sung Wook

Abstract

OBJECTIVE
The STONE score was developed to gauge the ureter stone probability. On the other hand, it is unclear if the STONE score is also applicable to Koreans. This study evaluated whether the STONE score can identify patients with suspected nephrolithiasis for whom a computed tomography (CT) scan can be obtained in the emergency department, targeting Koreans.
METHODS
Patients presenting to the emergency medicine (ED) with flank pain and a suspicion of a ureter stone between January 2016 and December 2016 were reviewed retrospectively. After calculating the STONE score, the enrolled patients were classified into the low, moderate, high score group. In each group, the prevalence of a ureter stone and other clinical diseases on a CT scan were investigated.
RESULTS
Among the 156 patients included in the analysis, 124 (79.5%) had a ureter stone and an alternative diagnosis was made in 12 (7.7%). The prevalence of a ureter stone and alternative diseases in the high score group was 87.7% (71/81) and 4.9% (4/81), respectively. The proportion of patients with nephrolithiasis increased significantly (P < 0.001), but the proportion of patients with other clinical diseases did not decrease significantly across the score groups (P=0.196). The area under the receiver operating characteristic curve was 0.711 (95% confidence interval, 0.633-0.780; P=0.001) with a cut off score higher than 8 (sensitivity 82.3%, specificity 50.0%) for the STONE score.
CONCLUSION
In this setting, the STONE score had a low specificity and could not accurately assess a ureter stone. More studies aimed at Koreans are warranted before a CT scan can be limited using the STONE score.