Nephrometry and cumulative morbidity after partial nephrectomy

BACKGROUND: Nephrometry scores aid in clinical decision-making, yet evidence is scarce regarding their impact on cumulative morbidity following partial nephrectomy (PN).

PATIENTS AND METHODS: Retrospective, monocentric study of 122 patients with suspicious renal masses undergoing open or robot-assisted PN between January 2019 and August 2020. Morbidity assessment followed European Association of Urology guidelines on complication reporting. 30-d complications were extracted using a PN-specific catalog, were graded by the Clavien-Dindo classification (CDC), and Comprehensive Complication Index (CCI®) values were calculated. The impact of nephrometry on cumulative morbidity was evaluated by (1) comparing morbidity estimates between Preoperative Aspects and Dimensions Used for an Anatomical (PADUA)/R.E.N.A.L. complexity groups, (2) by Pearson's correlation between nephrometry scores and CCI®, and (3) by multivariable regression models using any 30-d complication and 30-d CCI® as endpoints.

RESULTS: Of 122 patients, 101 (83%) underwent open and 21 (17%) robot-assisted PN. Median PADUA and R.E.N.A.L. scores were 9 (interquartile range, IQR 8-10) and 8 (IQR 6-9), respectively. Of 218 complications in 92 patients (75%), the majority was classified as minor (CDC grade ≤IIIa). Median 30-d CCI® was 8.7 (IQR 0.50-15). There was a small positive correlation between PADUA or R.E.N.A.L. score with CCI® (all P ≤ 0.026), explaining 4.7% and 4.1% of the variation in CCI®, respectively. After adjustment, nephrometry scores were associated with any 30-d complication and the CCI® (all P ≤ 0.011). PADUA and R.E.N.A.L. high complexity tumors were positively associated with both morbidity endpoints compared to low complexity tumors (all P ≤ 0.041).

CONCLUSIONS: At a referral center, PN may be safely performed, even if morbidity assessment follows a strict protocol. Nephrometry risk classification does only marginally translate into clinical relevant differences regarding short-term complications. Thus, nephron-sparing surgery should not be withheld from patients with high complexity renal masses.