Is there a financial disincentive to perform partial nephrectomy?

Validation of 3D volumetric-based renal function prediction calculator for nephron sparing surgery

OBJECTIVE

To evaluate a recently published volume-based renal function prediction calculator intended to be used in small renal mass surgical counseling.

METHODS

Retrospective data collection included three-dimensional calculation of renal mass and parenchyma of patients who have undergone extirpative therapy. The predicted glomerular filtration rate (GFR) was calculated using the online calculator. The predicted GFR was compared with the actual 6-month GFR. The Pearson correlation coefficient, paired t test and root-mean-square error (RMSE) are utilized for statistical analysis.

RESULTS

After institutional review board approval, three institutions provided data for analysis. After patients with renal mass size >300 cc, renal size >400 cc or preoperative CKD ≥stage 3 had been excluded, we retrospectively analyzed data from 136 patients. The median mass volume was 22.2 cc (IQR 7-49). In multiple linear regression analysis, the most significant variables predicting postoperative GFR were partial versus radical nephrectomy and preoperative GFR with an overall R² of .68 (F = 26.13, P < .001). The predicted GFR was 75.4 mL/min/1.73 m² compared to an actual GFR of 70.7 mL/min/1.73 m² (P < .001, paired t test). The predicted GFR was highly correlated with the actual postoperative GFR at 6 months (Pearson correlation, r = .65, P < .001). RMSE of the validation cohort was 16.87.

CONCLUSIONS

The predictive tool to determine renal function benefit of nephron sparing surgery compared to radical nephrectomy online calculator effectively predicts GFR and could potentially be used to help urologists and patients discuss renal function prior to extirpative renal surgery.

Parenchymal Volumetric Assessment as a Predictive Tool to Determine Renal Function Benefit of Nephron-Sparing Surgery Compared with Radical Nephrectomy

PURPOSE

To develop a preoperative prediction model using a computer-assisted volumetric assessment of potential spared parenchyma to estimate the probability of chronic kidney disease (CKD, estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m(2)) 6 months from extirpative renal surgery (nephron-sparing surgery [NSS] or radical nephrectomy [RN]).

PATIENTS AND METHODS

Retrospective analysis of patients who underwent NSS or RN at our institution from January 2000 to June 2013 with a compatible CT scan 6-month renal function follow-up was performed. Primary outcome was defined as the accuracy of 6-month postoperative eGFR compared with actual postoperative eGFR based on root mean square error (RMSE). Models were constructed using renal volumes and externally validated. A clinical tool was developed on the best model after a given surgical procedure using area under the curve (AUC).

RESULTS

We identified 130 (51 radical, 79 partial) patients with a median age of 58 years (interquartile range [IQR] 48-67) and preoperative eGFR of 82.1 (IQR 65.9-104.3); postoperative CKD (eGFR <60) developed in 42% (55/130). We performed various linear regression models to predict postoperative eGFR. The Quadratic model was the highest performing model, which relied only on preoperative GFR and the volumetric data for a RMSE of 15.3 on external validation corresponding to a clinical tool with an AUC of 0.89.

CONCLUSION

Volumetric-based assessment provides information to predict postoperative eGFR. A tool based on this equation may assist surgical counseling regarding renal functional outcomes before renal tumor surgical procedures.

Evaluation of national trends in the utilization of partial nephrectomy in relation to the publication of the American Urologic Association guidelines for the management of clinical T1 renal masses

Background

Partial nephrectomy has been underutilized in the United States. We investigated national trends in partial nephrectomy (PN) utilization before and after publication of the American Urological Association (AUA) Practice Guideline for management of the clinical T1 renal mass.

Methods

We identified adult patients who underwent radical (RN) or PN from November 2007 to October 2011 in the Nationwide Inpatient Sample (NIS). PN prevalence was calculated prior to (11/2007-10/2009) and after Guidelines publication (11/2009-10/2011) and compared the rate of change by linear regression. We also examined the nephrectomy trends in patients with chronic kidney disease (CKD). Statistical analysis included linear regression to determine point-prevalence of PN rates in CKD patients and logistic regression to identify variables associated with PN.

Results

During the study period, 30,944 patients underwent PN and 64,767 RN. The prevalence PN increased from 28.9% in the years prior to guideline release to 35.3% in the years following guideline release with an adjusted odds ratio (OR) of 1.24 (CI 1.01–1.54; p = 0.049). The rate of PN significantly increased throughout the study period (R² 0.15, p = 0.006): however, the rate of change was not increased after the guidelines. (p = 0.46). Overall rate of PN in patients with CKD did not increase over time (R² 0.0007, p = 0.99).

Conclusion

We noted a 6.4% absolute increase in PN after release of the AUA guidelines on clinical T1 renal mass was published; however, the rate of increase was not likely associated with guideline release. The rate of PN performed is increasing; however, further investigation regarding medical decision-making surrounding PN is needed.