Defining Risk Categories for a Significant Decline in Estimated Glomerular Filtration Rate After Robotic Partial Nephrectomy: Implications for Patient Follow-up.

Following partial nephrectomy (PN), it is important to prevent any deterioration in estimated glomerular filtration rate (eGFR). At present there are no evidence-based recommendations on when a nephrology consultation should be requested and how to adjust postoperative management when the risk of renal function decline is high. In an effort to address this void, we used our previously published nomogram to define risk groups for a significant decline in eGFR at 3-15 mo after PN. We used the nomogram-derived probability as the independent variable for the classification and regression tree and identified four risk groups: low (0-10%), intermediate (10-21%), high (21-65%), and very high (65-100%). Overall, 336 (34%), 386 (39%), 243 (24%), and 34 (4%) patients fell in the low, intermediate, high, and very high risk groups, respectively. The rates of significant eGFR decline across the low, intermediate, high, and very high risk groups were 4%, 14%, 29%, and 79%. With the low risk category as a reference, the hazard ratio for eGFR decline was 3.21 (95% confidence interval [CI] 1.83-5.64) for the intermediate, 7.80 (95% CI 4.52-13.48) for the high, and 27.24 (95% CI 13.8-53.8) for the very high risk group (all p<0.001). These prognostic risk categories can be used to design postoperative follow-up schedules. A multidisciplinary approach can be considered for patients at high and very high risk of eGFR decline. PATIENT SUMMARY: We propose a new stratification system to identify individuals at high risk of a decline in renal function after robotic partial nephrectomy.