Development and assessment of a nomogram for predicting the probability of achieving trifecta in patients with urolithiasis undergoing percutaneous nephrolithotomy

Background: The trifecta standard is a newly proposed criteria for evaluating the outcome of percutaneous nephrolithotomy, which take into account the capability of different PCNL techniques to fully clear renal stones and patient comfort and quality of life. Our purpose was to develop a novel nomogram to preoperatively predict the outcomes of percutaneous nephrolithotomy (PCNL) based on the new concept, trifecta. Methods: A total of 201 patients who received PCNL between June 2021 and June 2022 were included. The least absolute shrinkage and section operator (LASSO) method was used to select the optimal predictive features, and multivariable logistic regression analysis was utilized to construct a predictive model by incorporating the factors selected with the LASSO regression model. Discrimination, calibration, and clinical usefulness of the predictive model were assessed using the C-index, calibration plot, and decision curve analysis. Internal validation was assessed using bootstrapping validation. Result: Factors included in the nomogram were urine culture result, aciduria, maximum cross-sectional area (CSA) of stone, stone amount, stone density, number of affected calices, lower calyx affected, and hydronephrosis degree. The model exhibited promising discrimination with a C-index of 0.781, and internal validation exhibited a C-index value of 0.747. Decision curve analysis showed the nomogram was clinically useful when intervention was decided at the achieving trifecta possibility threshold of 14%. Conclusion: The nomogram developed exhibits a satisfactory predictive value for predicting the probability of achieving trifecta in patients undergoing PCNL. It may also assist in preoperative management to increase the probability of achieving trifecta. Trial registration ChiCTR2200055385, June 2021, retrospectively registered.