A Novel Metric for Hospital Quality in Kidney Cancer Surgery: A Veterans Affairs National Health System Validation of Concept.

INTRODUCTION: We aimed to develop and validate a Compound Quality Score (CQS) as a metric for hospital-level quality of surgical care in kidney cancer at the Veterans Affairs National Health System. METHODS: A retrospective review of 8,965 patients with kidney cancer treated at Veterans Affairs (2005-2015) was performed. Two previously validated process quality indicators (QIs) were explored: the proportion of patients with 1) T1a tumors undergoing partial nephrectomy and 2) T1-T2 tumors undergoing minimally invasive radical nephrectomy. Demographics/comorbidity/tumor characteristics/treatment year were used for case mix adjustments at hospital level. The predicted versus observed ratio of cases was calculated per hospital to generate QI scores using indirect standardization and multivariable regression models. CQS represents the sum of both scores. A total of 96 hospitals were grouped by CQS, and short-term patient-level outcomes were regressed on CQS levels to assess for length of stay (LOS), 30-day complications/readmission, 90-day mortality and total cost of surgical admission. RESULTS: CQS identified 25/33/38 hospitals with higher/lower/average performance, respectively. High performance hospitals had higher nephrectomy volumes (p <0.01). Total CQS independently associated with LOS (ß=-0.04, p <0.01, predicted LOS 0.84 days shorter for CQS=2 versus CQS=-2), 30-day surgical complications (OR=0.88, p <0.01) or 30-day medical complications (OR=0.93, p <0.01) and total cost of surgical admission (ß =-0.014, p <0.01, predicted 12% lower cost for CQS=2 versus CQS=-2). No association was found between CQS and 30-day readmissions or 90-day mortality (all p >0.05), although low event rates were observed (8.9% and 1.7%, respectively). CONCLUSIONS: Variability in quality of surgical care at hospital level can be captured with the CQS among patients with kidney cancer. CQS is associated with relevant short-term perioperative outcomes and surgical cost. QIs should be used to identify, audit and implement quality improvement strategies across health systems.

New Baseline Renal Function after Radical or Partial Nephrectomy: A Simple and Accurate Predictive Model.

PURPOSE: Preoperative estimation of new baseline glomerular filtration rate after partial nephrectomy or radical nephrectomy for renal cell carcinoma has important clinical implications. However, current predictive models are either complex or lack external validity. We aimed to develop and validate a simple equation to estimate postoperative new baseline glomerular filtration rate. MATERIALS AND METHODS: For development and internal validation of the equation, a cohort of 7,860 patients with renal cell carcinoma undergoing partial nephrectomy/radical nephrectomy (2005-2015) at the Veterans Affairs National Health System was analyzed. Based on preliminary analysis of 94,327 first-year postoperative glomerular filtration rate measurements, new baseline glomerular filtration rate was defined as the final glomerular filtration rate within 3 to 12 months after surgery. Multivariable linear regression analyses were applied to develop the equation using two-thirds of the renal cell carcinoma Veterans Administration cohort. The simplest model with the highest coefficient of determination (R2) was selected and tested. This model was then internally validated in the remaining third of the renal cell carcinoma Veterans Administration cohort. Correlation/bias/accuracy/precision of equation were examined. For external validation, a similar cohort of 3,012 patients with renal cell carcinoma from an outside tertiary care center (renal cell carcinoma-Cleveland Clinic) was independently analyzed. RESULTS: New baseline glomerular filtration rate (in ml/minute/1.73 m2) can be estimated with the following simplified equation: new baseline glomerular filtration rate = 35 + preoperative glomerular filtration rate (× 0.65) - 18 (if radical nephrectomy) - age (× 0.25) + 3 (if tumor size >7 cm) - 2 (if diabetes). Correlation/bias/accuracy/precision were 0.82/0.00/83/-7.5-8.4 and 0.82/-0.52/82/-8.6-8.0 in the internal/external validation cohorts, respectively. Additionally, the area under the curve (95% confidence interval) to discriminate postoperative new baseline glomerular filtration rate ≥45 ml/minute/1.73 m2 from receiver operating characteristic analyses were 0.90 (0.88, 0.91) and 0.90 (0.89, 0.91) in the internal/external validation cohorts, respectively. CONCLUSIONS: Our study provides a validated equation to accurately predict postoperative new baseline glomerular filtration rate in patients being considered for radical nephrectomy or partial nephrectomy that can be easily implemented in daily clinical practice.

Partial Nephrectomy for Patients with Severe Chronic Kidney Disease-Is It Worthwhile?

PURPOSE: Partial nephrectomy is prioritized over radical nephrectomy in patients with chronic kidney disease whenever feasible. However, we hypothesized that some patients with severe chronic kidney disease might rapidly progress to end stage renal disease, in which case the morbidity that can be associated with partial nephrectomy would not be justified. MATERIALS AND METHODS: A retrospective review of all 62 patients with stage IV chronic kidney disease undergoing partial nephrectomy at our institution (1999-2015) was performed. We analyzed preoperative/intraoperative factors and postoperative outcomes. Survival-analyses evaluated factors associated with time-to-progression to end stage renal disease the primary end point. RESULTS: Median age was 67 years, 71% of patients were male, and 84% Caucasian. Comorbidities included hypertension (94%), cardiovascular disease (53%) and diabetes (32%). Median preoperative estimated glomerular filtration rate was 23 ml/minute/1.73 m2 and 73% had an open approach. Benign pathology was found in 10 (16%) patients; only 23 (37%) and 7 (11%) patients had tumor grade 3/4 or pT3a disease, respectively. Unfavorable outcomes occurred in 15 patients (24%) defined as either 90-day mortality (3%), postoperative complication Clavien IIIb or greater (14%), or positive surgical margin (12%). Median time to progression to end stage renal disease was only 27 months (58 months for preoperative glomerular filtration rate greater than 25 ml/minute/1.73 m2 versus only 14 months when preoperative glomerular filtration rate was less than 20 ml/minute/1.73 m2). On multivariable analysis African American race (HR 2.55 [1.10-5.95]), preoperative estimated glomerular filtration rate 20 to 25 ml/minute/1.73 m2 or less than 20 ml/minute/1.73 m2 (HR 2.59 [1.16-5.84] and 5.03 [2.03-12.4], respectively) and minimally invasive approach (HR 2.05 [1.01-4.19]) were independently associated with progression to end stage renal disease. CONCLUSIONS: Our data suggest that some patients with stage IV chronic kidney disease undergoing partial nephrectomy have substantial comorbidities and nonaggressive pathology, and are at risk for unfavorable perioperative outcomes and rapid-progression to end stage renal disease. Renal mass biopsy should be strongly considered to improve patient-selection. Alternate strategies (active surveillance or radical nephrectomy) may be more appropriate, particularly when partial nephrectomy is high complexity or when the patient is African American, or preoperative glomerular filtration rate is less than 25 ml/minute/1.73 m2.

Compensatory Changes in Parenchymal Mass and Function after Radical Nephrectomy.

PURPOSE: Loss of renal function remains a major limitation of radical nephrectomy. The extent of renal functional compensation by the preserved kidney after radical nephrectomy has not been adequately studied in this elderly population with comorbidities. MATERIALS AND METHODS: A total of 273 patients treated with radical nephrectomy without end stage renal disease with available preoperative nuclear renal scans were included in the analysis. Renal functional compensation was defined as percent change in estimated glomerular filtration rate of the preserved kidney after radical nephrectomy. Estimated glomerular filtration rate was calculated by the Chronic Kidney Disease-Epidemiology Collaboration formula up to 5 years postoperatively. Preoperative/postoperative parenchymal volumes of the preserved kidney were measured from cross-sectional imaging. Multiple regression was used to identify predictive factors for renal functional compensation. RESULTS: Median age was 67 years and 67% of the patients were male. Overall 70% had hypertension, 26% diabetes and 37% preexisting chronic kidney disease. Locally advanced (T3a or greater) tumors were found in 53% of cases. Renal functional compensation was observed at 2 weeks (median 10%) and increased during the first 3 months (median 26%) after radical nephrectomy. Functional stability was then observed to 5 years. Renal parenchymal volume increased a median of 10% at 3 to 12 months but in addition, the functional efficiency per unit of parenchymal volume also increased 8% (estimated glomerular filtration rate units/cm3 of parenchyma was 0.236 postoperatively vs 0.208 preoperatively, p=0.004). Age (-0.85, p <0.01), global preoperative estimated glomerular filtration rate (-0.28, p <0.01) and split renal function of the removed kidney (0.61, p <0.01) were independent predictors of renal functional compensation. CONCLUSIONS: Percent renal functional compensation after radical nephrectomy is greater in younger patients, when preoperative estimated glomerular filtration rate is lower and when the removed kidney has more robust function. Increases in measurable parenchymal mass and functional efficiency contribute substantially to renal functional compensation.

Split renal function in patients with renal masses: utility of parenchymal volume analysis vs nuclear renal scans.

OBJECTIVES: To evaluate the utility of parenchymal volume analysis (PVA) for estimation of split renal function (SRF) in patients with renal masses. SRF is important for deciding about partial vs radical nephrectomy (PN/RN) and assessing risk for developing severe chronic kidney disease after surgery. For renal donors PVA is routinely used to estimate SRF, but the utility of PVA for the more complex renal mass population remains undefined. PATIENTS AND METHODS: All patients (n = 374) with renal tumours and a normal contralateral kidney managed with PN (2010-2018), with preoperative/postoperative nuclear renal scans (NRS) and cross-sectional imaging were analysed. Parenchymal volumes were measured by free-hand scripting or software analysis. Concordance between ipsilateral estimated glomerular filtration rate (eGFR) values based on SRF from NRS vs PVA were evaluated by Pearson correlation and Bland-Altman plots. Parallel analysis of all 155 patients managed with RN at our centre (2006-2016) with preoperative NRS and imaging was also performed. RESULTS: For PN, the median age and tumour size were 62 years and 3.4 cm, respectively. The median preoperative ipsilateral parenchymal volume and eGFR were 181 cm3 and 36.9 mL/min/1.73 m2 , respectively. Parenchymal volumes estimated by free-hand scripting vs software analyses correlated strongly (r = 0.98, P < 0.001). Preoperative ipsilateral eGFR based on SRF from PVA vs NRS also correlated strongly (r = 0.94, P < 0.001). Ipsilateral eGFR saved after PN correlated strongly with parenchymal volume preserved (all r >0.60); however, the correlation was much stronger when ipsilateral eGFRs were based on SRF from PVA rather than NRS (z-statistic = 3.15, P = 0.002). For RN patients, preoperative eGFR in the contralateral kidney based on SRF from PVA vs NRS also correlated strongly (r = 0.87, P < 0.001). CONCLUSION: PVA has utility for estimation of SRF in patients with renal masses, even though this population is older and more comorbid than renal donors and the tumour can complicate the analysis. PVA can be obtained by software analysis from preoperative cross-sectional imaging and thus readily incorporated into routine clinical practice.

Functional Comparison of Renal Tumor Enucleation Versus Standard Partial Nephrectomy.

BACKGROUND: Tumor enucleation (TE) optimizes parenchymal preservation and could yield better function than standard partial nephrectomy (SPN), although data on this are conflicting. OBJECTIVE: To compare functional outcomes for TE and SPN strategies. DESIGN, SETTING, AND PARTICIPANTS: Patients managed with partial nephrectomy (PN) with necessary data for analysis of preservation of ipsilateral parenchymal mass (IPM) and global glomerular filtration rate (GFR) from two centers were included. All studies were required <2 mo before and 3-12 mo after surgery. Patients with a solitary kidney or multifocal tumors were excluded. INTERVENTION: Partial nephrectomy. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Vascularized IPM was estimated from contrast-enhanced CT scans preoperatively and postoperatively. Serum creatinine-based estimates of global GFR were also obtained in the same timeframes. Univariable and multivariable linear regression evaluated factors associated with new-baseline global GFR. RESULTS/LIMITATIONS: Analysis included 71 TE and 373 SPN cases. The median preoperative global GFR was comparable for TE and SPN (75 vs 78ml/min/1.73m2; p=0.6). The median tumor size was 3.0cm for TE and 3.3cm for SPN (p=0.03). The median RENAL score was 7 in both cohorts. For TE, warm ischemia and zero ischemia were used in 51% and 49% of cases, respectively. For SPN, warm ischemia and cold ischemia were used in 72% and 28% of patients, respectively. Capsular closure was performed in 46% of TE and 100% of SPN cases (p<0.001). Positive margins were found in 8.5% of TE and 4.8% of SPN patients (p=0.2). The median vascularized IPM preserved was 95% (interquartile range [IQR] 91-100%) for TE and 84% (IQR 76-92%) for SPN (p<0.001). The median global GFR preserved was 101%(IQR 93-111%) and 89% (IQR 81-96%) for TE and SPN, respectively (p<0.001). On multivariable analysis, resection strategy, preoperative GFR, and vascularized IPM preserved were all significantly associated (p<0.001) with new-baseline global GFR. Limitations include the retrospective design and the lack of resection outcome data. CONCLUSIONS: Our analysis suggests that TE has potential for maximum IPM preservation compared to SPN and may provide optimized functional recovery. Further investigation will be required to evaluate the clinical significance of these findings. PATIENT SUMMARY: Tumor enucleation for kidney cancer involves dissection along the tumor capsule and optimally preserves normal kidney tissue, which may lead to better functional recovery. The importance of this approach in various clinical settings will require further investigation.

Excised Parenchymal Mass During Partial Nephrectomy: Functional Implications.

OBJECTIVE: To evaluate whether excised parenchymal mass (EPM) during partial nephrectomy (PN) correlates with functional decline and can serve as a surrogate for functional outcomes. MATERIALS AND METHODS: All 215 patients managed with PN for unifocal renal mass with necessary studies to determine EPM and percent glomerular filtration rate (GFR) and parenchymal mass preserved (both global and specific to the operated kidney) were analyzed. EPM was estimated from the pathologic specimen by subtracting the tumor mass from the specimen mass, with both calculated using the elliptical formula. Vascularized parenchymal mass preserved was measured from computed tomography scans obtained <2 months prior and 3-12 months after surgery. All functional analyses were required to be within the same time frames, and patients with a contralateral kidney were also required to have nuclear renal scans. RESULTS: The median tumor size was 3.5 cm and the median R.E.N.A.L. was 7. Warm and cold ischemia were utilized in 123 and 92 patients, respectively (median ischemia time = 23 minutes). The median global GFR preserved was 89%, the median total parenchymal mass preserved was 93%, and the median estimated EPM was 16 cm3. Whereas percent parenchymal mass preserved correlated strongly with global and ipsilateral GFR preserved (both P < .001), EPM failed to correlate with functional outcomes on both univariable and multivariable analyses. CONCLUSION: Our data suggest that parenchymal mass preserved with standard PN by experienced surgeons associates strongly with function preserved, whereas EPM fails to correlate with functional outcomes. Further study of the functional impact of EPM in other circumstances will be required, such as enucleation or PN performed by less-experienced surgeons.

Acute Ipsilateral Renal Dysfunction after Partial Nephrectomy in Patients with a Contralateral Kidney: Spectrum Score to Unmask Ischemic Injury.

BACKGROUND: Acute ischemic injury in the operated kidney after partial nephrectomy (PN) is often masked by a functional contralateral kidney; however, there is no practical method to assess this and its prognostic significance has not been defined. OBJECTIVE: We propose a spectrum score to reflect the degree of ischemic insult in the ipsilateral kidney and study its relationship to subsequent functional recovery. DESIGN, SETTING, AND PARTICIPANTS: From 2007 to 2014, 243 patients with a functional contralateral kidney underwent PN with necessary studies for detailed analysis of function and parenchymal mass before and after surgery in the ipsilateral kidney. Based on split function and percent parenchymal mass preserved in the ipsilateral kidney, we determined: serum creatinine (SCr)ideal-peak: expected peak SCr presuming no ischemic injury; and SCrworstcase-peak: expected peak SCr presuming temporary complete nonfunction of the ipsilateral kidney. The acute ipsilateral renal dysfunction spectrum score was defined: (observed peak SCr - SCrideal-peak)/(SCrworstcase-peak - SCrideal-peak). Subsequent functional recovery was defined: (percent function preserved)/(percent mass saved). INTERVENTION: PN. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Factors associated with spectrum score and relationship between spectrum score and subsequent functional recovery were evaluated by linear regression. RESULTS AND LIMITATIONS: Median duration of warm ischemia (n=152) was 21min (interquartile range [IQR] = 15-27) and hypothermia (n=91) 26min (IQR=23-30). Median parenchymal mass preservation was 83% (IQR=74-91%). Warm ischemia and longer ischemia duration associated with higher spectrum score (both p<0.05). Increased spectrum score (<25%, 25-50%, 50-75%, and >75% quartiles) had decreased functional recovery (98%, 94%, 90%, and 89%, respectively, p<0.001). However, this trend was not observed in the hypothermia cohort. On multivariable analysis spectrum score and ischemia type significantly associated with functional recovery (both p<0.01), while age and comorbidities failed to associate (p=0.3-0.7). CONCLUSIONS: Acute ipsilateral renal dysfunction spectrum score unmasks the degree of ischemic insult in the operated kidney after PN and associates with functional recovery. While increased spectrum score associates with suboptimal recovery, even patients with a high spectrum score reached 89-90% recovery. PATIENT SUMMARY: Acute functional decline after partial nephrectomy is difficult to evaluate in patients with two kidneys, but a proposed spectrum score can be used to evaluate this. Increased spectrum score reflects increased ischemia and may impact the functional recovery of the kidney.