Matched-pair analysis of renal function in the immediate postoperative period: a comparison of living kidney donors versus patients nephrectomized for renal cell cancer

[Renal functional compensation after unilateral radical nephrectomy of renal cell carcinoma]

OBJECTIVE

To investigate factors influencing renal functional compensation(RFC) of the preserved kidney after radical nephrectomy (RN).

METHODS

A total of 286 patients treated with RN in Peking University People's Hospital were retrospectively analyzed. Preoperative body mass index (BMI), systolic blood pressure (SBP), history of smoking, history of chronic diseases and other basic information, as well as preoperative blood biochemistry, urine routine, imaging examination results were recorded. All the patients underwent ^99mtechnetium-diethylenetriamine pentaacetic acid (^99mTc-DTPA) renal scans before operation. The surgical method, pathology and blood creatinine values from 1 month to 60 months after RN were recorded. Preoperative and postoperative estimated glomerular filtration rate (eGFR) was calculated by the chronic kidney disease epidemiology collaboration (CKD-EPI) formula. Renal functional compensation was defined as percent change in eGFR of the preserved kidney after RN compared with the preoperative eGFR. Univariate and multivariate regression analyses were used to identify predictive factors of RFC.

RESULTS

Median age was 61 years and 65.4% of the patients were male. Early stage (T1 or T2) tumors were found in 83.6% of the cases. 18.5% of the patients had preoperative diabetes mellitus, 39.5% had hypertension, 19.2% had a history of smoking, and 27.6% were found to have renal cyst on the contralateral side. In the study, 226 cases underwent laparoscopic radical nephrectomy and 60 cases underwent open radical nephrectomy. Renal clear cell carcinoma was the most common pathological type, accounting for 88.5%. The median tumor maximum diameter was 4.5 cm (0.7-13.5 cm). Median renal function compensation was 27% one month after radical nephrectomy. Functional stability was then observed to 5 years. The results of univariate analysis showed that age, gender, preoperative blood uric acid, preoperative urine protein, contralateral renal cyst, and percentage of split renal function of contralateral kidney were correlated with RFC (P < 0.05). Among them, UA level and split renal function of contralateral kidney were strongly negatively correlated with RFC. The results of multivariate linear regression analysis showed age (P < 0.001), blood uric acid (P < 0.001), urine protein (P=0.002), preoperative eGFR (P < 0.001) and the split renal function of contralateral kidney (P < 0.001) were independent predictors of RFC.

CONCLUSION

The basic examinations, such as blood biochemistry, urine routine and renal scan before RN are of great significance in predicting the compen-satory ability of the preserved kidney after RN, which is supposed to be taken into consideration when making clinical decision.

Unexpected Outcomes of Renal Function after Radical Nephrectomy: Histology Relevance along with Clinical Aspects

Acute kidney injury (AKI) and chronic kidney disease (CKD) are common events after radical nephrectomy (RN). In this study we aimed to predict AKI and CKD after RN relying on specific histological aspects. We collected data from a cohort of 144 patients who underwent radical nephrectomy. A histopathological review of the healthy part of the removed kidney was performed using an established chronicity score (CS). Logistic regression analyses were performed to predict AKI after RN, while linear regression analysis was adopted for estimated glomerular filtration rate (eGFR) variation at 1 year. The outcomes of the study were to determine variables correlated with AKI onset, and with eGFR decay at 1 year. The proportion of AKI was 64%. Logistic analyses showed that baseline eGFR independently predicted AKI (odds ratio 1.04, 95%CI 1.02:1.06). Moreover, AKI (Beta −16, 95%CI −21:−11), baseline eGFR (Beta −0.42, 95%CI −0.52:−0.33), and the presence of arterial narrowing (Beta 10, 95%CI 4:15) were independently associated with eGFR decline. Our findings showed that AKI onset and eGFR decline were more likely to occur with higher baseline eGFR and lower CS, highlighting that RN in normal renal function patients represents a more traumatic event than its CKD counterpart.

Comparison of long-term kidney functions after radical nephrectomy and simple nephrectomy

Objective

To determine if there is a difference in proceeding to CKD between patients who had undergone radical nephrectomy (RN) and simple nephrectomy (SN) for different indications by comparing the short- and long-term renal function.

Materials and Methods

We retrospectively analyzed the records of all patients who underwent nephrectomy (either for malign or benign indications) in our clinic between January 2007 and September 2017. The patients were divided into 2 groups according the type of surgery: 1) Radical nephrectomy Group, 2) Simple Nephrectomy Group. Renal function was evaluated with Glomerular Filtration Rate (GFR) calculated using the MDRD formula.

Results

A total of 276 patients were included in the study. There were 202 patients in RN Group and 74 patients in SN Group. The mean age of the patients in RN Group and SN Group were age 59,2 ± 11,5 and 49,9 ± 15,1 years, respectively (p = 0.001). GFR levels of patients in RN Group versus SN Group were as follows: Preoperative period: 84.9 vs. 81 mL/min/1.73 m²; postoperative 1st day: 60.5 vs. 84.4 mL/min/1.73 m², postoperative 1st month 58.9 vs. 76 mL/min/1.73 m², postoperative 1st year: 59.5 vs. 74.1 mL/min/1.73 m²; at last control 60.3 and 76.1 mL/min/1.73 m². While preoperative GFR was found to be similar in two groups (p = 0.26), postoperative GFR values were found to be significantly lower in Group RN (p < 0.001). In comparison of the decrease in GFR in two groups at last follow-up, significantly higher decrease was observed in RN Group, 29% vs. 6%, (p < 0.05).

Conclusion

The decrease in GFR exists more common and intensive after RN compared to SN. In long-term, compensation mechanisms that develop after sudden nephron loss like radical nephrectomy deteriorates kidney function more than gradual nephron loss as in benign etiologies which indicates simple nephrectomy.

Predictive model of 1-year postoperative renal function after living donor nephrectomy

OBJECTIVE

Kidney transplantation from a living donor nephrectomy (LDN) is the best treatment for end-stage renal disease, but decrease in donor renal function is often revealed. The aim of this study was to evaluate the association between preoperative factors and postoperative estimated glomerular filtration rate (eGFR) and test a predictive model to estimate postoperative eGFR, 1 year after LDN.

PATIENTS AND METHODS

We reviewed 226 records of consecutive patients who underwent laparoscopic live donor nephrectomy between 2006 and 2014 in a single tertiary center. Of these, complete data on 202 patients were analyzed. A training (2/3 of the whole population) and a validation set (1/3) were randomized. A multivariate regression model was used to identify predictors and a formula to estimate of 1-year postoperative eGFR in the training set, using the CKD-EPI formula. Then, the formula was subjected to internal validation using the validation set using receiver operating characteristic (ROC) curves.

RESULTS

Two hundred and two LLDN were evaluated with a mean preoperative eGFR of 94.1 ± 15.5 ml/min/1.73 m² and postoperative eGFR of 64.6 ± 14.5 ml/min/1.73 m² (p < 0.0001). In multivariable analysis, age and preoperative eGFR were independent predictors of postoperative eGFR in the training set. A formula to estimate postoperative eGFR was generated with Pearson r = 0.70 in the training cohort and 0.65 in the validation cohort (both p < 0.0001). Area under the ROC curve of the formula was 0.89 in the training cohort and 0.83 in the validation cohort (both p < 0.0001).

CONCLUSIONS

Preoperative eGFR and age are predictors of postoperative eGFR after LDN. The internally validated predictive model of postoperative eGFR developed could be an accurate tool to improve the selection of LDN candidates.

Cystatin-C is associated with partial recovery of kidney function and progression to chronic kidney disease in living kidney donors: Observational study

Donor nephrectomy in living-donor kidney transplantation may result in hyperfiltration injury in remnant kidney; however, its clinical implication in partial recovery of kidney function (PRKF) in remnant kidney and chronic kidney disease (CKD) progression remains unclear. Thus, we investigated the effect of PRKF on CKD development in the residual kidney and the utility of cystatin-C (Cys-C) in evaluating renal function in living-donor kidney transplantation donors.The electronic medical records and laboratory results of 1648 kidney transplant (KT) donors and 13,834 healthy nondonors between January 2006 and November 2014 were reviewed. The predictors of PRKF and CKD diagnosed by Kidney Disease: Improving Global Outcomes (KDIGO) criteria were evaluated by multivariate analysis. CKD risk was compared between KT donors and healthy nondonors using Cox proportional hazard regression analysis following propensity score matching (PSM).The incidence of PRKF for KT donors was 49.3% (813). CKD incidence was 24.8% (408) in KT donors and 2.0% (277) in healthy nondonors. The predictors of PRKF were, male sex (odds ratio [OR], 17.32; 95% confidence interval [CI] 9.16-32.77), age (OR, 1.02; 95% CI, 1.00-1.04; P < 0.001), Cys-C concentration (OR, 1.02; 95% CI, 1.00-1.04; P = 0.02), and preoperative albumin level (OR, 0.49; 95% CI, 0.27-0.89; P = 0.02). The predictors of CKD were age (hazards ratio [HR], 1.04; 95% CI, 1.02-1.05; P < 0.001), Cys-C concentration (HR, 1.024; 95% CI, 1.012-1.037; P < 0.001), and PRKF (HR, 1.41; 95% CI, 1.04-1.92; P = 0.03). After PSM, the risk of progression to CKD was higher in KT donors than in healthy nondonors (HR, 58.4; 95% CI, 34.2-99.8; P < 0.001).Donor nephrectomy is associated with PRKF and progression to CKD. Cys-C is a useful early marker for detecting PRKF and CKD.

Comparison of preoperative adaptive enlargement of the contralateral normal kidney in patients nephrectomized for benign non-functioning kidney versus renal cell carcinoma

OBJECTIVES

To investigate the potential effects of preoperative volumetric compensation of the contralateral normal kidney on renal function after simple nephrectomy or radical nephrectomy.

METHODS

A total of 306 patients (80 simple nephrectomy patients and 226 radical nephrectomy patients) with 1:3 propensity score matching were included between October 1996 and December 2013. Preoperative three-dimensional kidney volume was estimated from computed tomography images using a specialized volumetric program. Glomerular filtration rate assessed using the Chronic Kidney Disease Epidemiology Collaboration equations was checked preoperatively, 1 week, 3 months and 1 year after nephrectomy.

RESULTS

Preoperative mean Chronic Kidney Disease Epidemiology Collaboration glomerular filtration rate was 76.5 mL/min/1.73 m(2) in the simple nephrectomy group and 89.2 mL/min/1.73 m(2) in the radical nephrectomy group. In simple nephrectomy patients, mean Chronic Kidney Disease Epidemiology Collaboration glomerular filtration rate showed a stable pattern up to 3 months (75.5 mL/min/1.73 m(2) at 7 days and 76.2 mL/min/1.73 m(2) at 3 months), and decreased slightly to 72.6 mL/min/1.73 m(2) at 1 year. However, in radical nephrectomy patients, mean Chronic Kidney Disease Epidemiology Collaboration glomerular filtration rate decreased immediately to 63.4 mL/min/1.73 m(2) at 7 days after surgery, and then increased gradually to 64.6 mL/min/1.73 m(2) at 3 months and 65.9 mL/min/1.73 m(2) at 1 year. Preoperative mean contralateral normal kidney volume was 225.7 mL in the simple nephrectomy group and 180.1 mL in the radical nephrectomy group (P < 0.001). The contralateral normal kidney volume to total normal kidney volume ratio was 0.74 in the simple nephrectomy group and 0.51 in the radical nephrectomy group (P < 0.001).

CONCLUSIONS

Preoperative volumetric compensation of the contralateral normal kidney is important to maintain postoperative renal function in patients undergoing nephrectomy.

Living Donor Hepatectomy: Is it Safe?

Living donor hepatectomy (LDH) is high risk to a healthy donor and remains controversial. Living donor nephrectomy (LDN), conversely, is a common practice. The objective is to examine the outcomes of LDH and compare this risk profile to LDN. The Nationwide Inpatient Sample was queried for hepatectomies and nephrectomies from 1998 to 2011. LDH or LDN were identified by donor ICD-9 codes. Outcomes included in-hospital mortality and complications. Bivariate analysis compared nondonor hepatectomy or nondonor nephrectomy (NDN). Multivariate analyses adjusted for baseline organ disease, malignancy, or benign lesions. There were 430 LDH and 9211 nondonor hepatectomy. In-hospital mortality was 0 and 6 per cent, respectively ( P < 0.001); complications 4 and 33 per cent ( P < 0.001). LDH had fewer complications [odds ratio (OR) 0.15 (0.08–0.26)]. There were 15,631 LDN and 117,966 NDN. Mortality rates were 0.8 per cent LDN and 1.8 per cent NDN ( P < 0.001). Complications were 1 and 21 per cent ( P < 0.001). LDN had fewer complications [OR 0.06 (0.05–0.08)] and better survival [OR 0.32 (0.18–0.58)]. Complication rates were higher in LDH than LDN (4% vs 1%, P < 0.001), but survival was similar (0% vs 0.8% mortality, P = 0.06). In conclusion, morbidity and mortality rates of LDH are significantly lower than hepatectomy for other disease. This study suggests that the risk profile of LDH is comparable with the widely accepted LDN.

Survival and Functional Stability in Chronic Kidney Disease Due to Surgical Removal of Nephrons: Importance of the New Baseline Glomerular Filtration Rate

BACKGROUND

Chronic kidney disease (CKD) can be associated with a higher risk of progression to end-stage renal disease and mortality, but the etiology of nephron loss may modify this. Previous studies suggested that CKD primarily due to surgical removal of nephrons (CKD-S) may be more stable and associated with better survival than CKD due to medical causes (CKD-M).

OBJECTIVE

We addressed limitations of our previous work with comprehensive control for confounding factors, differentiation of non-renal cancer-related mortality, and longer follow-up for more discriminatory assessment of the impact of CKD-S.

DESIGN, SETTING, AND PARTICIPANTS

From 1999 to 2008, 4299 patients underwent surgery for renal cancer at a single institution. The median follow-up was 9.4 yr (7.3-11.0). The new baseline glomerular filtration rate (GFR) was defined as the highest GFR between the nadir and 42 d after surgery. Three cohorts were retrospectively evaluated: no CKD (new baseline GFR >60 ml/min/1.73 m(2)); CKD-S (new baseline GFR<60 but preoperative >60 ml/min/1.73 m(2)); and CKD-M/S (new baseline and preoperative GFR both <60 ml/min/1.73 m(2)). Cohort status was permanently set at 42 d after surgery.

INTERVENTION

Renal surgery.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Decline in renal function (50% reduction in GFR or dialysis), all-cause mortality, and non-renal cancer mortality were examined using a multivariable Cox proportional hazards model.

RESULTS AND LIMITATIONS

CKD-M/S had a higher incidence of relevant comorbidities and the new baseline GFR was lower. On multivariable analysis (controlling for age, gender, race, diabetes, hypertension, and cardiac disease), CKD-M/S had higher rates of progressive decline in renal function, all-cause mortality, and non-renal cancer mortality when compared to CKD-S and no CKD (hazard ratio [HR] 1.69-2.33, all p<0.05). All-cause mortality was modestly higher for CKD-S than for no CKD (HR 1.19, p=0.030), but renal stability and non-renal cancer mortality were similar for these groups. New baseline GFR of <45 ml/min/1.73 m(2) significantly predicted adverse outcomes. The main limitation is the retrospective design.

CONCLUSIONS

CKD-S is more stable than CKD-M/S and has better survival, approximating that for no CKD. However, if the new baseline GFR is <45 ml/min/1.73 m(2), the risks of functional decline and mortality increase. These findings may influence counseling for patients with localized renal cell carcinoma and higher oncologic potential when a normal contralateral kidney is present.

PATIENT SUMMARY

Survival is better for surgically induced chronic kidney disease (CKD) than for medically induced CKD, particularly if the postoperative glomerular filtration rate is ≥45 ml/min/1.73 m(2). Patients with preexisting CKD are at risk of a significant decline in kidney function after surgery, and kidney-preserving treatment should be strongly considered in such cases.