OBJECTIVE:

To analyze the predictive performance of a nomogram and identify other predictive variables of stone-free rate, as well as to evaluate the current status of extracorporeal shock wave lithotripsy in the treatment of kidney stones.

MATERIALS AND METHODS:

The prospective evaluation of the Kim nomogram as a predictive tool for stone-free rate after extracorporeal shock wave lithotripsy in patients previously assessed through computed tomography was carried out. Stone status was determined 3 weeks after treatment. The predictive yield of the Kim nomogram versus the reference study (computed tomography) was evaluated for predicting stone-free status. Bayesian statistics were performed to calculate the prevalence of stones after the test and the ROC curve analysis was carried out to determine the area under the curve for all values, as well as to report the 95% CI.

RESULTS:

A total of 110 patients were included in the study. Extracorporeal lithotripsy showed a general efficacy of 69% and the nomogram analysis produced an area under the curve of 0.627. The number of stones and the maximum diameter were statistically significant variables for achieving the stone-free rate. Stone volume and Hounsfield units were also predictive in the final treatment result.

CONCLUSIONS:

Extracorporeal shock wave lithotripsy is still an effective treatment for kidney stones. A better selection of patients that are candidates for said treatment can be made utilizing the predictive variables identified.

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