*Article* **Robust Association between Acute Kidney Injury after Radical Nephrectomy and Long-Term Renal Function**

**Won Ho Kim 1,\*, Kyung Won Shin 1, Sang-Hwan Ji 1, Young-Eun Jang 1, Ji-Hyun Lee 1, Chang Wook Jeong 2, Cheol Kwak <sup>2</sup> and Young-Jin Lim <sup>1</sup>**


Received: 9 January 2020; Accepted: 24 February 2020; Published: 25 February 2020

**Abstract:** The association between acute kidney injury (AKI) and long-term renal function after radical nephrectomy has not been evaluated fully. We reviewed 558 cases of radical nephrectomy. Postoperative AKI was defined by the Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine criteria. Values of estimated glomerular filtration rate (eGFR) were collected up to 36 months (median 35 months) after surgery. The primary outcome was new-onset chronic kidney disease (CKD) stage 3a or higher or all-cause mortality within three years after nephrectomy. The functional change ratio (FCR) of eGFR was defined as the ratio of the most recent GFR (24–36 months after surgery) to the new baseline during 3–12 months. A multivariable Cox proportional hazard regression analysis for new-onset CKD and a multivariable linear regression analysis for FCR were performed to evaluate the association between AKI and long-term renal outcomes. A correlation analysis was performed with the serum creatinine ratio and used to determine AKI and FCR. AKI occurred in 43.2% (*n* = 241/558) and our primary outcome developed in 40.5% (*n* = 226/558) of patients. The incidence of new-onset CKD was significantly higher in patients with AKI than those without at all follow-up time points after surgery. The Cox regression analysis showed a graded association between AKI and our primary outcome (AKI stage 1: Hazard ratio 1.71, 95% confidence interval 1.25–2.32; AKI stage 2 or 3: Hazard ratio 2.72, 95% confidence interval 1.78–4.10). The linear regression analysis for FCR showed that AKI was significantly associated with FCR (β = −0.168 ± 0.322, *p* = 0.011). There was a significant negative correlation between the serum creatinine ratio and FCR. In conclusion, our analysis demonstrated a robust and graded association between AKI after radical nephrectomy and long-term renal functional deterioration.

**Keywords:** acute kidney injury; radical nephrectomy; chronic kidney disease; functional change ratio
