Patient factors predict complications after partial nephrectomy: validation and calibration of the Preoperative Risk Evaluation for Partial Nephrectomy (PREP) score.

OBJECTIVES: To develop and validate the Preoperative Risk Evaluation for Partial Nephrectomy (PREP) score to predict the probability of major postoperative complications after partial nephrectomy (PN) based on patient comorbidities. PATIENTS AND METHODS: The Premier Healthcare Database was used to identify patients who had undergone elective PN. Through review of International Classification of Diseases ninth revision codes, we identified patient comorbidities and major surgical complications (Clavien-Dindo Grade III-V). Multivariable logistic regression was used to identify predictors of major complications. We used half of the set as the training cohort to develop our risk score and the other half as a validation cohort. RESULTS: From 2003 to 2015, 25 451 PNs were performed. The overall rate of major complications was 4.9%. The final risk score consisted of 10 predictors: age, sex, congestive heart failure, coronary artery disease, chronic obstructive pulmonary disease, chronic kidney disease, diabetes, hypertension, obesity, and smoking. In the training cohort, the area under the receiver operating characteristic curve (AUC) was 0.75 (95% confidence interval [CI] 0.73-0.78), while the AUC for the validation cohort was 0.73 (95% CI 0.70-0.75). The predicted probabilities of major complication in the low- (≤10 points), intermediate- (11-20 points), high- (21-30 points), and very high-risk (>30 points) categories were 3% (95% CI 2.6-3.2), 8% (95% CI 7.2-9.2), 24% (95% CI 20.5-27.8), and 41% (95% CI 34.5-47.8), respectively. CONCLUSIONS: We developed and validated the PREP score to predict the risk of complications after PN based on patient characteristics. Calculation of the PREP score can help providers select treatment options for patients with a cT1a renal mass and enhance the informed consent process for patients planning to undergo PN.

Determinants of urolithiasis before and after parathyroidectomy in patients with primary hyperparathyroidism.

OBJECTIVE: To assess the determinants of urolithiasis in patients with primary hyperparathyroidism (PHPT) before and after parathyroidectomy (PTX). METHODS: Institutional Research Ethics approval was obtained. A retrospective review was performed for patients presenting with PHPT to the stone, surgical oncology, and otolaryngology clinics at 2 tertiary-care centers from January 2006 to November 2011. Demographic, clinical, and surgical data were collected together with 24-hour urine collections before and after PTX. RESULTS: Of 332 patients undergoing PTX, 255 (68.2% female patients) had PHPT. Mean age was 60.3 years (range, 18-91). Before PTX, renal calcification was detected in 51 (20%) patients, nephrolithiasis in 48 (18.8%), and nephrocalcinosis in 3 (1.2%) patients. Compared with PHPT patients without stones, PHPT patients with stones were significantly younger (56.4 vs 61.3 years, P=.02), less likely to be female (54.9% vs 71.9%, P=.03), and had significantly lower levels of vitamin D (19.7 vs 23.5 ng/mL, P=.03). Nine patients (3.5%) developed stones after PTX and were found to have significantly higher post-PTX total serum calcium levels when compared with those without stones. Although hypercalciuria was detected in 62% of pre-PTX stone formers, none of those who tested had post-PTX hypercalciuria (P<.001). On multivariate regression analysis, post-PTX stone formation was associated with male gender (adjusted odds ratio [95% confidence interval]: 6.8 [5.3-7.2], P=.01) and post-PTX hypercalcemia (adjusted odds ratio [95% confidence interval]: 1.48 [1.33-2.12], P=.02). CONCLUSION: Pre-PTX urolithiasis was associated with younger age, male gender, and lower levels of vitamin D, whereas post-PTX urolithiasis was independently predicted by male gender and hypercalcemia.