Objective: To evaluate the association between renal tumour scoring systems and open partial nephrectomy ischemia time.
Methods: A historical cohort of open partial nephrectomy patients at The Ottawa Hospital between 2002 and 2009 was reviewed. Preoperative patient characteristics (age, gender, preoperative renal function, diabetes, hypertension, smoking history, heart disease) and ischemia time were abstracted from medical records. Preoperative computed tomography (CT) images were reviewed and tumours were characterized using three scoring systems: (1) R.E.N.A.L. nephrometry score (radius, exophytic/endophytic properties, nearness of tumour to the collecting system or sinus in millimetres, anterior/posterior, location relative to polar lines); (2) preoperative aspects and dimensions used for anatomic (PADUA) classification; and (3) Centrality index (C index). Patients without preoperative CT and patients treated with laparoscopic partial nephrectomy were excluded.
Results: During the study period, 78 patients met the inclusion criteria. Median R.E.N.A.L. score was 7 (interquartile range [IQR] 5-8), median PADUA score was 8 (IQR 7-10), and mean C index was 3.9 (standard deviation [SD] 2.1). Mean ischemia time was 23.4 (SD 10.8) minutes. Five individual tumour characteristics (diameter, nearness to collecting system, anterior/posterior location, medial/lateral location, and collecting system involvement) were strongly associated with ischemia time (p < 0.05). Increased R.E.N.A.L. score (1.5 minutes per unit 95%CI 0.08, 2.9, p = 0.04) and PADUA score (2.0 minutes per unit 95%CI 0.5, 3.5, p = 0.009) were significantly associated with ischemia time. An increasing C index score was also associated with ischemia time (-1.1 minutes per unit 95%CI -2.2, 0.04, p = 0.06), but the association was not statistically significant.
Conclusion: Renal tumour characteristics are associated with ischemia time. The proposed scoring systems are useful descriptors of surgical complexity and should be used when describing partial nephrectomy patients. Prospective evaluation and refinement of scoring systems are required to create an optimized model prior to widespread application.