C index is associated with both short-term and long-term renal functional outcome after partial nephrectomy

ObjectivesPartial nephrectomy is the standard treatment for the small renal mass. C index, one of the nephrometric systems, was found to be associated with short-term renal functional outcome after laparoscopic partial nephrectomy. We conducted this study to externally validate the application of C index as a prognostic factor of long-term renal functional outcome after open partial nephrectomy (OPN) for small renal mass.Materials and MethodsThe medical records of 65 consecutive patients undergoing OPN from June 2004 to November 2011 were reviewed. C index was calculated on preoperative computed tomography or magnetic resonance images. The estimated glomerular filtration rate was calculated using the modification of diet in renal disease 2 equation. Short-term and long-term renal functional outcomes were assessed by the nadir estimated glomerular filtration rate within postoperative 1 week and 1 to 2 years. The correlation between C index, perioperative parameters, and renal functional outcomes were examined.ResultsThe median C index in our cohort was 2.2. C index was associated with operative time, cold ischemia time, estimated blood loss, and length of hospital stay (p = 0.03, 0.001, 0.001, and 0.02, respectively). On logistic linear regression analysis, C index (p = 0.01) and operative time (p < 0.001) were associated with the short-term percent decrease of the estimated glomerular filtration rate, whereas C index (p = 0.03) was associated with the long-term percent decrease of the estimated glomerular filtration rate. Under the criteria of C index ≤ 2.5, the sensitivity/specificity were 83.3%/53.8% and 80%/52% in predicting chronic kidney disease stage 3 or greater in the short-term and long-term follow-up, respectively. Moreover, the mean long-term percent decrease of the estimated glomerular filtration rate in patients with C index ≤ 2.5 was much higher compared with that of patients with C index > 2.5 (18.1% vs. 0%, p = 0.001).ConclusionC index could serve as an indicator for both short-term and long-term renal functional decrease after OPN. For patients with C index ≤ 2.5, a comprehensive analysis of vascular anatomy and planning for dissection are crucial in preoperative assessment, and every effort should be exerted to minimize renal parenchymal damage during surgery.