Development of a simple nomogram to estimate risk for intraoperative complications before partial nephrectomy based on the Mayo Adhesive Probability score combined with the RENAL nephrometry score

Purpose This study aimed to develop a simple nomogram based on the Mayo Adhesive Probability (MAP) score combined with the RENAL nephrometry score (RNS) to predict intraoperative complications before partial nephrectomy (PN) in Asian populations. Materials and methods This study retrospectively collected patients undergoing PN at three medical centers. Each component of the MAP score and the RNS (6 variables) was evaluated to assess its association with intraoperative complications by multivariable logistic regression with backward elimination. Results A total of 46 cases (7.2%) with intraoperative complications were identified among 637 patients. After backward elimination, three variables, including tumor diameter (4-7 cm vs. ≤4 cm: odds ratio [OR], 4.339; 95% confidence interval [CI], 1.943-9,692; ≥7 cm vs. ≤4 cm: OR, 8.434; 95% CI, 1.225-58.090), nearness to the collecting system (4-7 mm vs. ≥7 mm: OR, 2.988; 95% CI, 1.293-6.907; ≤4 mm vs. ≥7 mm: OR, 21.394; 95% CI, 6.122-74.756), and perirenal fat stranding type (type 1 vs. no stranding: OR, 3.119; 95% CI, 1.079-9.017; type 2 vs. no stranding: OR, 18.722; 95% CI, 6.757-51.868), were retained. The predictive power (measured by area under the curve [AUC]) of the nomogram was observed to be superior to the RNS or MAP score alone (RNS: 0.686, MAP score: 0.729, the nomogram: 0.837), but comparable to their combination (0.813). Conclusions The simple nomogram contains fewer components than the combination of the RNS and MAP scores yet demonstrates equivalent predictive power for intraoperative complications.