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Renal Function decline in patients undergoing partial nephrectomy
Scott V. Wiener, MD1, Christian Bartels, MD1, Peter Haddock, PhD2, Ilene Staff, PhD2, Anoop Meraney, MD2.
1University of Connecticut, Farmington, CT, USA, 2Hartford Hospital, Hartford, CT, USA.
Background: Both active surveillance (AS) and partial nephrectomy (PN) are being increasingly utilized in the clinical management of patients with small renal masses (SRM). Patients selected for AS are typically older and with significant comorbid conditions compared to patients undergoing PN. However, both patient groups experience a decline in renal function at follow-up that is related to increasing age, comorbid conditions and/or surgical resection. The aim of our study was to identify individual risk factors responsible for this decline in renal function, and to compare the impact of surgical and non-surgical risk factors on worsening CKD scores in the patient populations.
Methods: We retrospectively identified all patients with a small renal mass who underwent either PN or AS between 1999 to 2015 at our clinical center. Patients were excluded if they had multiple tumors or crossed over from AS to PN. Partial nephrectomies were performed under warm or cold ischemia based on surgeon discretion. As most cases were performed utilizing warm ischemia, a statistical comparison could not be performed. Univariate and multivariate analysis compared age, BMI, Charlson Comorbidity Index (CCI), Tumor Size, CKD stage and "worsening of CKD stage" based on an increase in British CKD stage category between initial diagnosis and the most recent follow up.
Results: 52 (13.3%) and 339 (86.7%) patients underwent AS or PN, respectively. Follow up times were 1.7 (0.8-2.8) and 1.5 (0.5-3.0) years for AS and PN patients, respectively (p=0.28). While AS patients were older than their PN counterparts (p=0.004) and had higher initial CKD stage (p<0.001), there was no significant difference in CCI score between groups (p=0.195). In multivariable analyses, age and PN were associated with a worsening of CKD stage (p=0.011; 0.013). In multivariable analyses, patients aged >65, CCI score, better initial renal function (CKD 1 or 2), and PN were associated with a worsening of CKD stage (p=0.027, 0.010, 0.001, 0.029). Ischemia types [cold (n=44), warm (n=231), and no ischemia (n=64)] did not predict CKD worsening on univariate and multivariate analysis. 7 patients declined by >1 CKD stage; all underwent PN.
Conclusions: PN is a significant risk factor for a decline in renal function. Older patients with preserved renal function at baseline are at the highest risk for a post-PN decline in renal function.
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