A new tool for predicting the efficiency of mini-percutaneous nephrolithotomy

Magomedov D.M., Kotov S.V., Pulbere S.A., Bolotov A.D., Gradskova T.E.

1) FGAOU VO N.I. Pirogov Russian National Research Medical University of the Ministry of Health of Russia, Moscow, Russia; 2) Pirogov City Clinical Hospital No.1, Moscow, Russia; 3) «Kommunarka» Moscow Multidisciplinary Clinical Center of Moscow Health Department, Moscow, Russia

Introduction. Currently, percutaneous nephrolithotomy (PCNL) is a first-line treatment method for large and staghorn kidney stones. Predicting the efficiency of the performed surgical procedure is relevant at the stage of preoperative counseling of patients. Aim. To develop a universal nomogram for predicting the efficiency of mini-PCNL taking into account the baseline characteristics and features of the patient. Materials and methods. A total of 251 patients with kidney stones who underwent mini-PCNL in the prone position according to the standard method through a single access were included in the study. The preoperative characteristics of patients and their impact on the outcome were evaluated. An achievement of the stone-free rate (SFR) was assessed by the computed tomography (CT). Results. The analysis revealed factors significantly influencing the achievement of the SFR, such as stone volume >1.39 cm3 (p=0.001), stone area >189.03 mm2 (p=0.001), distance from the lowest point of the Th12 to the lower part of the lower pole calyx (T12-LP) <85.81 mm (p=0.050), distances from the lower calyx to the most cranial part of the iliac crest (ICLP) >49.1 mm (p=0.029), stone size >18.2 mm (p=0.001), number of involved calyxes >3 (p=0.001), number of involved calyxes for staghorn stones >4 (p=0.001), and staghorn stone (p=0.001). Correlation, logistic regression, and ROC analysis were performed for these factors. The area under the curve (AUC) was 0.897. A nomogram has been developed. The sensitivity of the model is 94.4%, specificity is 59.2%, and overall accuracy is 84.4%. A certificate of state registration of a computer program in the IBM SPSS Statistics syntax language "A model for predicting the SFR of mini-PCNL in patients with kidney stones" was obtained. Conclusion. The nomogram developed on the basis of our data showed a high predictive ability in relation to the SFR with sensitivity of 94%. This nomogram is easy to use and interpret, which makes it convenient for routine practice, however, external validation is necessary to objectify the predictive ability.

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About the Authors

Corresponding author: D.M. Magomedov – Ph.D. student of the Department of Urology and Andrology, FGAOU VO N.I. Pirogov Russian National Research Medical University of the Ministry of Health of Russia, Moscow, Russia; urologist at the Urologic Department of the Pirogov City Clinical Hospital No.1, Moscow, Russia; e-mail: magomedov.dzhanay@yandex.ru

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