Nephrometry scores are designed to characterize tumors and stratify the surgical complexity. It remains unclear as to which nephrometry score can accurately predict the surgical outcomes. We aimed to assess the utility of radius, exophytic/endophytic, nearness, anterior/posterior, location (RENAL), preoperative aspects and dimensions used for anatomic classifications (PADUA), and centrality index (C-index) nephrometry scores for predicting the strict Trifecta achievement from a single institution series robotic-assisted partial nephrectomy (RAPN). We retrospectively identified the prospectively maintained robotic surgery database records of 91 patients who underwent RAPN between June 2015 and September 2020 in Antalya Training and Research Hospital. The main outcome of the study was the achievement of strict Trifecta (negative surgical margin, no major urologic complications, warm ischemia time ≤25 min, and ≥85% preservation of estimated glomerular filtration rate). A multivariable analysis was performed to identify the factors of strict Trifecta success. The mean patient age was 55.82 ± 13.37 years with a median clinical tumor size of 3.5 cm (IQR 2.5–4.9). The median RENAL, PADUA, and C-index score were 7(IQR 6–8), 8(IQR 7–10), and 2.01(IQR 1.64–2.72), respectively. A strict Trifecta could be achieved in 54 patients (59.3%). Clinical tumor size (P = 0.011), RENAL risk groups (low:reference; intermediate; P = 0.040; high; P = 0.009), PADUA risk groups (low:reference; intermediate; P = 0.044; high; P = 0.001) and C-index risk groups (low:reference; high; P = 0.015) were the independent predictors of strict Trifecta attainment in the multivariate analysis. None of the nephrometry scores were a superior predictor compared to other nephrometry scores in comparative analysis. RENAL, PADUA, and C-index scores were all independent predictors of a strict Trifecta achievement. Our comprehensive comparison of the three scores identified that none of the nephrometry scores proved to be inferior to others nephrometry scores.
The incidental detection of small renal masses has increased in the present times, and the cases of renal cell carcinoma (RCC) are more frequently diagnosed due to the widespread use of imaging modalities for unrelated reasons (
The main aim of PN should be to completely remove the tumor with minimal complication and minimal decrease in renal function. In order to simplify and standardize the reporting and comparison of the outcomes of PN, Hung et al. have proposed “Trifecta”, adopted from radical prostatectomy (
The nephrometry scores are designed to characterize tumor, facilitate cohort comparisons, and stratify surgical complexity. The radius, exophytic/endophytic, nearness, anterior/posterior, location (RENAL) nephrometry score, preoperative aspects and dimensions used for an anatomic classifications (PADUA) score, and the centrality index (C-index) remain the most known and used systems (
In this study, we aimed to comparatively assess which of three nephrometry scores corralates best with strict Trifecta achievement in RAPN.
Following the approval of the Institutional Review Board (approval number = 2020-286), we reviewed the charts of the patients who underwent RAPN for a suspicious renal mass between June 2015 and September 2020 in Antalya Training and Research Hospital. The data were retrospectively noted from a prospectively maintained database. The patients with solitary kidney (n = 2), missing data (n = 4), and a follow-up time shorter than 1 year (n = 40) were excluded from the study. The first 25 cases on the learning curve of the surgeons performing RAPN were also excluded. The final group for the study included 91 patients.
Before the surgery, all the patients underwent a contrast-enhanced computed tomograph (CT) or magnetic resonance imaging (MRI). RENAL, PADUA, and C-index scores were calculated by a radiologist (AGE) and an urologist (YA) according to the protocols described for these systems (
The indication for surgery was elective in all the cases. All 91 RAPN operations were carried out by two surgeons (MS and MA) using the da Vinci XI robotic surgical system (Intuitive Surgical Inc, Sunnyvale, CA, USA). Both transperitoneal and retroperitoneal accesses were utilized. The decision for the surgical approach was taken after assessing the location of the tumor and the surgeons’s preference. The vascular pedicle was dissected and isolated with the help of vascular silicon tapes. The decision to clamp renal hilum was taken during the surgery, based on the tumor characteristics and intraoperative findings. The tumor was identified visually and cut out by a cold scissors with 2–5 mm of the parenchymal margin. The tumor bed was oversewn with 3-0 V-lock, parenchymal sutures were made using the sliding clip technique.
Preoperative demographic data (gender, age, body mass index [BMI], and comorbidities), tumor characteristics (tumor side, clinical tumor size, RENAL, PADUA, and C-index scores), perioperative outcomes (surgical approach, WIT, estimated blood loss [EBL], operation time [OT], and hospitalization), and pathology features (tumor size, histological sub-types, tumor grade, pathological stage, and surgical margin status) were recorded. There were complications in the first 30 days after surgery, which were classified according to Clavien-Dindo system. OT was defined as the time from the placement of trocars to the removal of trocars.
The renal function of the group was evaluated preoperatively and 1 year after operation by serum creatinine levels and estimated glomerular filtration rate (eGFR), calculated by the modification of diet in renal disease (MDRD) formula. Preoperative creatinine levels were measured routinely for 3–7 days before the surgery. Absolute and percent change in eGFR was calculated based on the difference between the preoperative and postoperative up to 12 months.
Strict Trifecta was used for investigating the accomplishment of optimal outcomes of RAPN. The achievement of strict Trifecta was defined as the simultaneous fulfillment of the following factors: negative surgical margin, WIT≤25 min, renal function loss <15%, and no significant perioperative complications (Clavien-Dindo grade ≥3).
The statistical analysis was done using IBM SPSS Statistics for Windows, Version 23.0 (IBM Corp., Armonk, NY). The normality assumptions were controlled by the Shapiro–Wilk test. The descriptive analyses were presented using mean ± SD, median (IQR), or n (%), where appropriate. The categorical data were analyzed by Pearson chi-square and Fisher’s Exact test. Mann–Whitney U test and Student’s t test were used for the analysis of non-normally and normally distributed numerical data, respectively. The paired samples t-test was used for parametric comparison of repeated measurements. Friedman test with Bonferroni correction was used for the non-parametric comparison of parameters measured at different times. The receiver operating characteristic (ROC) curve analysis was applied to determine the optimal cut-off point of RENAL, PADUA, and C-index scores for predicting the achievement of strict Trifecta and area under the curve (AUC); sensitivity and specificity were calculated and reported with 95% confidence intervals. The optimal cut-off point of measurements was determined as the value of the maximum Youden index. Delong’s test was used for comparison of AUC values of nephrometry scores. Univariate and multivariate logistic regression analysis was used to determine the independent risk factors associated with the achievement of strict Trifecta. The variables with P < 0.1 in the univariate analyses were further tested in the multivariate model. Since RENAL, PADUA, and C-index score are highly correlated, a separate regression model was created for each variables. To determine the interobserver reliability between the urologist and radiologist for RENAL, PADUA, and C-index scores, the intraclass correlation coefficient (ICC) was calculated. Odds ratio (OR) with corresponding 95% confidence intervals (95% CIs) was reported. A P-value of less than 0.05 was considered statistically significant.
The descriptive statistics of the study group are shown in
Clinical characteristics of patients.
Variables | Overall | Achieving strict Trifecta | Not achieving strict Trifecta | P-Value |
---|---|---|---|---|
Number of patients | 91 | 54 | 37 | – |
Mean age, (years) | 55.82 ± 13.37 | 56.28 ± 12.83 | 55.16 ± 14.28 | 0.698 |
Gender, n (%) | ||||
Male | 64(70.3) | 38(70.4) | 26(70.3) | 0.992 |
Female | 27(29.7) | 16(29.6) | 11(29.7) | |
Mean BMI, (kg/m^{2}) | 27.13 ± 3.7 | 26.43 ± 3.51 | 28.16 ± 3.79 | |
Diabetes, n (%) | 11(12.1) | 7(13) | 4(10.8) | 0.999 |
Hypertension, n (%) | 27(29.7) | 14(25.9) | 13(35.1) | 0.345 |
Atherosclerosis, n (%) | 15(16.5) | 8(14.8) | 7(18.9) | 0.604 |
Surgical approach, n (%) | ||||
Transperitoneal | 74(81.3) | 41(75.9) | 33(89.2) | 0.111 |
Retroperitoneal | 17(18.7) | 13(24.1) | 4(10.8) | |
Tumor side, n (%) | ||||
Left | 52(57.1) | 32(59.3) | 20(54.1) | 0.622 |
Right | 39(42.9) | 22(40.7) | 17(45.9) | |
Median clinical tumor size, (IQR) (cm) | 3.5(2.5–4.9) | 3(2.3–4.2) | 4.6(3.5–5.4) | |
Hilar clamping, n (%) | ||||
Total clamp | 74(81.3) | 38(70.4) | 36(97.3) | |
Off clamp | 17(18.7) | 16(29.6) | 1(2.7) |
BMI, body mass index.
The operative findings and pathological outcomes are summarized in
Perioperative outcomes and pathological results.
Variables | Overall | Achieving strict Trifecta | Not achieving strict Trifecta | P-Value |
---|---|---|---|---|
Median WIT, (IQR) (min) | 24(16–29) | 19(0–24) | 30(28–32) | |
Median OT, (IQR) (min) | 140(120–170) | 127.5(110–150) | 155(140–180) | |
Median EBL, (IQR) (mL) | 100(60–200) | 100(50–200) | 150(100–200) | |
Median pathological tumor size, (IQR) (cm) | 3.5(2.5–5) | 2.8(2.1–4) | 4.5(3.5–5.5) | |
Tumor type, n (%) | ||||
Benign | 23(25.3) | 15(27.8) | 8(21.6) | 0.507 |
Malign | 68(74.7) | 39(72.2) | 29(78.4) | |
Benign subtype (n = 23), n (%) | ||||
Angiomyolipoma | 7(30.4) | 4(26.7) | 3(37.5) | 0.217 |
Chronic pyelonephritis | 2(8.7) | 1(6.7) | 1(12.5) | |
Benign cyst | 3(13) | 2(13.3) | 1(12.5) | |
Oncocytoma | 6(26.1) | 6(40) | 0(0) | |
Tubulointerstitial nephritis | 1(4.3) | 0(0) | 1(12.5) | |
Hydatid cyst | 2(8.7) | 1(6.7) | 1(12.5) | |
Ksantogranulomatosis | 1(4.3) | 1(6.7) | 0(0) | |
Metanephric adenoma | 1(4.3) | 0(0) | 1(12.5) | |
Malign subtype (n = 68), n (%) | ||||
Clear | 46(67.6) | 23(59) | 23(79.3) | 0.191 |
Papillary | 15(22.1) | 11(28.2) | 4(13.8) | |
Chromofobe | 7(10.3) | 5(12.8) | 2(6.9) | |
Positive surgical margin (n = 68), n (%) | 4(5.9) | 0(0) | 4(13.8) | |
Pathological stage (n = 68), n (%) | ||||
T1a | 38(55.9) | 30(76.9)^{a} | 8(27.6)^{b} | |
T1b | 26(38.2) | 9(23.1)^{a} | 17(58.6)^{b} | |
T2a | 2(2.9) | 0(0)^{a} | 2(6.9)^{a} | |
T3a | 2(2.9) | 0(0)^{a} | 2(6.9)^{a} | |
WHO/ISUP grade (n = 68), n (%) | ||||
1 | 14(20.6) | 12(30.8) | 2(6.9) | 0.051 |
2 | 42(61.8) | 21(53.8) | 21(72.4) | |
3 | 11(16.2) | 6(15.4) | 5(17.2) | |
4 | 1(1.5) | 0(0) | 1(3.4) | |
Complication, n (%) | 10(11) | 4(7.4) | 6(16.2) | 0.306 |
Complication grade (n = 10), n (%) | ||||
1 | 1(10) | 0(0) | 1(16.7) | 0.999 |
2 | 8(80) | 4(100) | 4(66.7) | |
3 | 1(10) | 0(0) | 1(16.7) | |
Hospitalization, (IQR) (days) | 3(3–3) | 3(3–3) | 3(3–3) | 0.375 |
WIT, warm ischemia time; OT, operation time; EBL, estimated blood loss; WHO/ISUP, World Health Organization/International Society of Urological Pathology.
The association of nephrometry scores and risk groups with strict Trifecta achievement is given in
Overall nephrometry scores and distrubitions.
Overall | Achieving strict Trifecta | Not achieving strict Trifecta | P-Value | |
---|---|---|---|---|
Median RENAL, (IQR) | 7(6–8) | 6(5–7) | 8(7–9) | |
RENAL risk, n (%) | ||||
Low | 33(36.3) | 28(51.9)^{a} | 5(13.5)^{b} | |
Moderate | 48(52.7) | 24(44.4)^{a} | 24(64.9)^{a} | |
High | 10(11) | 2(3.7)^{a} | 8(21.6)^{b} | |
Median PADUA, (IQR) | 8(7–10) | 8(7–8) | 10(9–11) | |
PADUA risk, n (%) | ||||
Low | 26(28.6) | 24(44.4)^{a} | 2(5.4)^{b} | |
Moderate | 36(39.6) | 22(40.7)^{a} | 14(37.8)^{a} | |
High | 29(31.9) | 8(14.8)^{a} | 21(56.8)^{b} | |
Median C-index, (IQR) | 2.01(1.64–2.72) | 2.47(1.96–3.53) | 1.66(1.42–1.89) | |
C-index risk, n (%) | ||||
Low | 31(34.1) | 28(51.9) | 3(8.1) | |
High | 60(65.9) | 26(48.1) | 34(91.9) |
RENAL, Radius, exophytic/endophytic, nearness, anterior/posterior, location; PADUA, Preoperative aspects and dimensions used for an anatomic classifications; C-index, Centrality index.
The renal functional change is demonstrated in
Preoperative and postoperative renal functional outcomes.
Variables | Overall | Achieving strict Trifecta | Not achieving strict Trifecta | P-Value |
---|---|---|---|---|
Median preoperative creatinine, (IQR) (mg/dL) | 0.95(0.82–1.08) | 0.93(0.82–1.07) | 0.96(0.83–1.1) | 0.513 |
Median postoperative creatinine, (IQR) (mg/dL) | 1.1(0.92–1.31) | 1.07(0.92–1.23) | 1.12(0.97–1.38) | 0.270 |
Median first year creatinine, (IQR) (mg/dL) | 1.01(0.84–1.2) | 0.96(0.79–1.12) | 1.04(0.87–1.24) | 0.131 |
Mean preoperative eGFR, (mL/min/1.73 m^{2}) | 82.68 ± 18.79 | 83.24 ± 18.11 | 81.86 ± 19.96 | 0.734 |
Mean first year eGFR, (mL/min/1.73 m^{2}) | 78.25 ± 19.31 | 80.8 ± 18.4 | 74.54 ± 20.25 | 0.130 |
Mean eGFR difference | -4.51 ± 8.42 | -2.61 ± 7.36 | -7.27 ± 9.17 | |
Mean eGFR percent change | -5.08 ± 10.22 | -2.83 ± 9.05 | -8.35 ± 11.04 |
eGFR, estimated glomerular filtration rate.
Differences between RENAL, PADUA and C-index score risk groups in terms of strict Trifecta components.
Variables | RENAL | PADUA | C-index | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Low | Moderate | High | P | Low | Moderate | High | P | Low | High | P | |
Strict Trifecta achievement, n (%) | 28(84.8)^{a} | 24(50)^{b} | 2(20)^{b} | 24(92.3)^{a} | 22(61.1)^{b} | 8(27.6)^{c} | 28(90.3) | 26(43.3) | |||
WIT, n (%) | |||||||||||
≤25 min | 29(87.9)^{a} | 26(54.2)^{b} | 3(30)^{b} | 25(96.2)^{a} | 22(61.1)^{b} | 11(37.9)^{b} | 29(93.5) | 29(48.3) | |||
>25 min | 4(12.1)^{a} | 22(45.8)^{b} | 7(70)^{b} | 1(3.8)^{a} | 14(38.9)^{b} | 18(62.1)^{b} | 2(6.5) | 31(51.7) | |||
Surgical margin (n = 68), n (%) | |||||||||||
Negative | 26(100) | 30(88.2) | 8(100) | 0.166 | 19(100) | 24(92.3) | 21(91.3) | 0.547 | 23(100) | 41(91.1) | 0.292 |
Positive | 0(0) | 4(11.8) | 0(0) | 0(0) | 2(7.7) | 2(8.7) | 0(0) | 4(8.9) | |||
Complication (grade≥3) (n = 10), n (%) | |||||||||||
No | 3(100) | 4(80) | 2(100) | 0.999 | 3(100) | 2(66.7) | 4(100) | 0.600 | 3(100) | 6(85.7) | 0.999 |
Yes | 0(0) | 1(20) | 0(0) | 0(0) | 1(33.3) | 0(0) | 0(0) | 1(14.3) | |||
Renal function reduction, n (%) | |||||||||||
≤15% | 31(93.9) | 42(87.5) | 7(70) | 0.117 | 25(96.2)^{a} | 35(97.2)^{a} | 20(69)^{b} | 30(96.8) | 50(83.3) | 0.090 | |
>15% | 2(6.1) | 6(12.5) | 3(30) | 1(3.8)^{a} | 1(2.8)^{a} | 9(31)^{b} | 1(3.2) | 10(16.7) |
RENAL, Radius, exophytic/endophytic, nearness, anterior/posterior, location; PADUA, Preoperative aspects and dimensions used for an anatomic classifications; C-index, Centrality index; WIT, warm ischemia time.
Strict Trifecta could be achieved in 54 patients (59.3%). The most common reason for the failure of strict Trifecta was prolonged WIT. Univariate and multivariate analyses were performed to evaluate the preoperative variables predicting strict Trifecta achievement (
Univariate and multivariate analyses of factors affecting the achievement of strict Trifecta.
Variables | Univariate analysis | Multivariate analysis with RENAL risk | Multivariate analysis with PADUA risk | Multivariate analysis with C-index risk | ||||
---|---|---|---|---|---|---|---|---|
OR (%95 CI) | P | OR (%95 CI) | P | OR (%95 CI) | P | OR (%95 CI) | P | |
Age | 1.006(0.975–1.038) | 0.694 | ||||||
Female gender | 0.995(0.398–2.486) | 0.992 | ||||||
BMI | 0.875(0.776–0.988) | 0.888(0.775–1.017) | 0.086 | 0.895(0.781–1.026) | 0.111 | 0.89(0.778–1.018) | 0.089 | |
Diabetes | 1.229(0.333–4.539) | 0.757 | – | – | – | – | – | – |
Hypertension | 0.646(0.26–1.603) | 0.346 | – | – | – | – | – | – |
Atherosclerosis | 0.745(0.245–2.27) | 0.605 | – | – | – | – | – | – |
Clinical tumor size | 0.499(0.347–0.718) | 0.596(0.4–0.887) | 0.642(0.435–0.946) | 0.674(0.449–1.01) | 0.056 | |||
Preoperative GFR | 1.004(0.982–1.027) | 0.730 | – | – | – | – | – | – |
RENAL score | 0.496(0.356–0.691) | – | – | – | – | – | – | |
RENAL risk | ||||||||
Low | Reference | – | Reference | – | – | – | – | – |
Moderate | 0.179(0.059–0.54) | 0.278(0.082–0.941) | – | – | – | – | ||
High | 0.045(0.007–0.275) | 0.074(0.011–0.521) | – | – | – | – | ||
PADUA score | 0.384(0.259–0.57) | – | – | |||||
PADUA risk | ||||||||
Low | Reference | – | – | – | Reference | – | – | – |
Moderate | 0.131(0.027–0.642) | – | – | 0.181(0.034–0.958) | – | – | ||
High | 0.032(0.006–0.166) | – | – | 0.058(0.01–0.333) | – | – | ||
C-index score | 7.278(2.818–18.797) | – | – | – | – | – | – | |
C-index risk | ||||||||
Low | Reference | – | – | – | – | – | Reference | – |
High | 0.082(0.022–0.299) | – | – | – | – | 0.163(0.038–0.699) |
RENAL, Radius, exophytic/endophytic, nearness, anterior/posterior, location; PADUA, Preoperative aspects and dimensions used for an anatomic classifications; C-index, Centrality index; BMI, body mass index; eGFR, estimated glomerular filtration rate.
The ability of the nephrometry scores to predict strict Trifecta outcomes was evaluated by ROC curve analysis (
Receiver operating characteristic analysis for RENAL, PADUA, and C-index score to predict the achievement of strict Trifecta.
All three nephrometry scores demonstrated good concordance between the two observers (
Concordance between urologist’s and radiologist’s score using intraclass correlation coefficient.
ICC | 95%CI | |
---|---|---|
Radius | 0.892 | 0.841–0.928 |
Exophytic/endophytic | 0.866 | 0.802–0.910 |
Nearness | 0.730 | 0.617–0.813 |
Location | 0.759 | 0.656–0.835 |
RENAL score | 0.832 | 0.756–0.886 |
Polar location | 0.822 | 0.742–0.879 |
Exophytic rate | 0.876 | 0.817–0.916 |
Renal rim | 0.825 | 0.746–0.881 |
Renal sinus | 0.656 | 0.521–0.759 |
UCS | 0.772 | 0.674–0.844 |
Tumor size | 0.911 | 0.867–0.940 |
PADUA score | 0.888 | 0.834–0.924 |
0.896 | 0.847–0.930 |
RENAL, Radius, exophytic/endophytic, nearness, anterior/posterior, location; PADUA, Preoperative aspects and dimensions used for an anatomic classifications; C-index; UCS, urinary collecting system.
In this study, the ability to predict strict Trifecta for RENAL, PADUA, and C-index scores were evaluated. We observed a good reproducibility of three nephrometry scores among the observers. RENAL, PADUA, and C-index scores were all independent predictor of a strict Trifecta achievement. Our comprehensive comparison of the three scores identified that none of the nephrometry scores proved to be inferior to the others.
The objective of PN is to achieve a satisfactory oncological outcome and minimize complications while preserving renal function to the extend possible. Accordingly, Hung et al. (
The Trifecta achievement rate in previous studies has ranged between 31.6% and 87.8% (
Nephrometry scores have been developed to describe tumor complexity and to standardize the reports of PN. An ideal nephrometry score should have some value in estimating surgical outcomes, and result in consistent scores between observers. In this study, we evaluated the RENAL, PADUA, and C-index scores which are most known and used ones. The correlation between urologist and radiologist seems to be sufficient to recommend the use of RENAL, PADUA, and C-index scores. Likewise, good concordance amongst readers was found in a study on interobserver variability of the RENAL, PADUA, and C-index for robotic and laparoscopic PN patients (
The predictors of Trifecta has been evaluated by several studies. In a Japanese multicenter study, tumor diameter, EBL and hilar location of the tumor were the independent predictors of Trifecta (
The present study has several limitations. Firstly, our database is prospectively recorded, and the analysis is carried out is retrospective. Secondly, the study involved a limited number of patients within a single center. Finally, RAPNs were performed by 2 surgeons. However, both surgeons have extensive experience with open, laparoscopic, and robotic PNs. Additionally, as we want to minimize the effects of the surgeons’ learning curve of RAPN, we excluded the first 25 patients for both surgeons.
Based on the results of this study, we suggest using RENAL, PADUA, and C-index scores to predict strict Trifecta outcomes preoperatively, with reproducible interobserver agreement. These scoring systems should undergo an external validation in prospective study with larger study group to predict the Trifecta success.
Nothing to declare from all authors.