AUA 2020: The Healthier the Patient, the Longer the Ischemia: Surgical Implications for Partial Nephrectomy in the RECORd2 Project

(UroToday.com) Ischemia time during partial nephrectomy is one of the greatest determinants of acute kidney injury. But whether this association is affected by the preoperative risk of acute kidney injury has never been investigated. At the 2020 American Urological Association (AUA) Virtual Meeting, Carlo Andrea Bravi, MD, and colleagues presented results of their study assessing the interaction between the preoperative risk of acute kidney injury and ischemia time on the probability of acute kidney injury during partial nephrectomy.

For this study, data for 944 patients treated with on-clamp partial nephrectomy for cT1 renal masses between 2013 and 2016 were extracted from the RECORd2 prospective multicenter database. Acute kidney injury was defined according to the RIFLE criteria, and the authors estimated the preoperative risk of acute kidney injury according to age, baseline estimated glomerular function rate (eGFR), clinical stage, PADUA score, and surgical approach. The coefficients from the multivariable model were used to build a nomogram for the prediction of acute kidney injury. Classification and regression tree (CART) analysis identified patients at “high” and “low” risk of acute kidney injury. Finally, the authors plotted the probability of acute kidney injury over ischemia time stratified by preoperative risk of acute kidney injury.

Overall, the median (interquartile range) age at surgery was 64 (54, 72) years, the median preoperative eGFR was 87 (73, 101) mL/min/1.73 m2, and the median warm ischemia time was 15 (12, 20) minutes. A total of 235 (25%) patients experienced acute kidney injury after surgery. At multivariable analysis, age (OR 1.03, 95% CI 1.02-1.05; p<0.0001), preoperative eGFR (OR 1.02, 95% CI 1.01-1.03; p=0.003), clinical T1b stage (OR 1.88, 95% CI 1.35-2.62; p=0.0002) and higher PADUA score (OR 1.20, 95% CI 1.05-1.37; p=0.007) were associated with increased risk of acute kidney injury. Conversely, laparoscopic (OR 0.47, 95% CI 0.26-0.84; p=0.011) and robotic (OR 0.39, 95% CI 0.25-0.60; p<0.0001) surgery had lower probability of acute kidney injury compared to open surgery.

According to the first split at CART analysis, patients were categorized as “high” and “low” risk of acute kidney injury have a probability greater or smaller than 40%. For low-risk patients, the probability of acute kidney injury in case of less than 10 versus more than 20 minutes of ischemia was 13% and 28%, respectively (absolute risk increase: 15%). By contrast, the risk of acute kidney injury for high-risk patients who had less than 10 versus more than 20 minutes of ischemia was 31% and 77% respectively (absolute risk increase: 45%). The risk of acute kidney injury over ischemia time during partial nephrectomy stratified by high and low-risk patients is as follows:

IschemiaTime_AUA2020.png

Dr. Bravi concluded his presentation assessing the impact of ischemia at the time of partial nephrectomy with the following take-home messages:

  • In patients treated with partial nephrectomy functional harm related to ischemia is highly dependent on baseline risk of acute kidney injury
  • Appropriate surgical planning should include the assessment of the individual risk of functional damage

Presented by: Carlo Andrea Bravi, MD, San Raffaele Hospital, Milan, Italy

Written by: Zachary Klaassen, MD, MSc – Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, Agusta, GA, USA, Twitter: @zklaassen_md, at the 2020 American Urological Association (AUA) Annual Meeting, Virtual Experience #AUA20, June 27-28, 2020

Related Content: 
Read: EAU 2018: Surgical Nomogram for Predicting the Likelihood of Postoperative Surgical Complications in Patients Treated with Partial Nephrectomy - The RECORd 2 Project 

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