External validation of STONE score and modified STONE score

ABSTRACT

OBJECTIVE@#The STONE score and modified STONE score are useful clinical prediction rules for ureteral calculi. This study performed an external validation of the STONE score and modified STONE score. The purpose of this study was to minimize the economic cost and radiation exposure of computed tomography.@*METHODS@#The electronic medical records of patients complaining of flank pain from January 2016 to December 2017 at a single emergency department were reviewed retrospectively. The patients were classified into three groups according to the STONE score and modified STONE score. The prevalence of urethral calculi and other important alternative diagnoses were calculated in each group.@*RESULTS@#Out of 561 patients, 266 patients were enrolled in this study, and 222 patients (83.5%) had a ureteral calculus. The same 266 patients were compared using the two clinical decision rule, STONE score, and the modified STONE score. The patients were classified into three groups. The prevalence of ureteral stones in the STONE score was 18.8% in the low-score group, 81.7% in the moderate-score group, and 91.1% in the high-score group. The prevalence of the modified STONE score was 20.0% in the low-score group, 54.1% in the moderate-score group, and 93.0% in the highscore group. The area under the curve of the modified STONE score was 0.779 higher than the area under the STONE score curve 0.73.@*CONCLUSION@#The modified STONE score has superior diagnostic specificity to the STONE score.