Validation of PADUA, RENAL, and SPARE Scores in Single-Port Robot-Assisted Partial Nephrectomy

Overview

This study retrospectively evaluated 211 patients undergoing single-port robot-assisted partial nephrectomy (SP-RAPN) to validate the predictive performance of PADUA, RENAL, and SPARE nephrometry scores. The primary endpoint was Trifecta achievement, defined as negative margins, no complications, and warm ischemia time ≤ 25 minutes. Results showed that all three scores predicted surgical outcomes with varying accuracy, with SPARE offering improved usability.

Background

Robot-assisted partial nephrectomy (RAPN) is a standard treatment for T1 renal tumors, with the single-port da Vinci platform enabling less invasive approaches. Anatomical nephrometry scores like PADUA and RENAL have been used to quantify tumor complexity and predict surgical morbidity, but they have limitations including moderate interobserver variability. The SPARE score was developed to simplify scoring while maintaining predictive accuracy. However, no large-scale validation of these scores has been performed specifically in the SP-RAPN setting, particularly using a retroperitoneal approach.

Data Highlights

Key Findings

• All three nephrometry scores (PADUA, RENAL, SPARE) were independently associated with Trifecta achievement after SP-RAPN.
• SPARE score demonstrated comparable predictive accuracy to PADUA and RENAL but with improved simplicity and reproducibility.
• Most tumors were classified as intermediate complexity by PADUA, low risk by SPARE, and low complexity by RENAL.
• The retroperitoneal approach was used in the majority (83.9%) of cases, facilitating direct renal hilum access without bowel mobilization.
• Trifecta achievement was defined by negative surgical margins, absence of perioperative complications, and warm ischemia time ≤ 25 minutes.
• Multivariable logistic regression adjusted for age, BMI, Charlson Comorbidity Index, and tumor size confirmed the independent predictive value of each score.

Clinical Implications

The SPARE score offers a simplified and reproducible alternative to PADUA and RENAL scores for preoperative tumor assessment in SP-RAPN, aiding surgical planning and risk stratification. Surgeons can rely on these validated nephrometry systems to predict perioperative outcomes and optimize patient counseling. The predominance of the retroperitoneal approach in SP-RAPN supports its feasibility and safety for T1 renal tumors.

Conclusion

This study provides the first large-scale external validation of PADUA, RENAL, and SPARE nephrometry scores specifically in the SP-RAPN setting, confirming their utility in predicting surgical outcomes. The SPARE score, with its streamlined framework, may enhance clinical applicability without compromising predictive performance.

References

1. Ficarra et al. 2009 -- PADUA score introduction
2. Kutikov and Uzzo 2009 -- RENAL score description
3. Ficarra et al. 2019 -- SPARE score development
4. Trifecta criteria reference
5. DeLong et al. -- AUC comparison methodology