Validation of the Mayo Adhesive Probability score as a predictor of adherent perinephric fat and outcomes in open partial nephrectomy.

Background: Adherent perinephric fat (APF) contributes to surgical complexity and can be associated with adverse perioperative outcomes for partial nephrectomy (PN). The Mayo Adhesive Probability (MAP) score accurately predicts the presence of APF during robotic-assisted partial nephrectomy (RAPN). Our primary aim is to validate MAP score as a predictor of APF in open partial nephrectomy (OPNx).

Methods: We reviewed 105 consecutive OPNx (100 patients) performed by a single surgeon with intraoperative determination of APF. We evaluated the ability of the MAP score to discriminate between those with APF and those without APF by estimating the area under the receiver operating characteristic curve (AUROCC). The association of perioperative outcomes with APF was evaluated as well.

Results: Forty-three patients [49%; 95% confidence interval (CI), 39-59%] had intraoperative identification of APF. The MAP score had excellent ability to predict APF in OPNx (AUROCC, 0.82; 95% CI, 0.74-0.92). APF was observed in 6% of patients with a MAP score of 0-1, 27% with score 2, 52% with score 3, 75% with score 4, and 90% with score 5. The presence of APF was associated with longer operative times (P=0.004) and higher estimated blood loss (EBL) (P=0.003). Although not statistically significant, our study did suggest that APF may be associated with postoperative complications and prolonged length of stay (LOS) (>3 days).

Conclusions: MAP score accurately predicts the presence of APF in patients undergoing OPNx. APF is associated with longer operative time and higher blood loss in OPNx.