A nephrolithometric nomogram to predict treatment success of percutaneous nephrolithotomy.

PURPOSE: Imaging is routinely done preoperatively and postoperatively to assess patients treated with percutaneous nephrolithotomy. We developed a nomogram for percutaneous nephrolithotomy success. MATERIALS AND METHODS: From November 2007 to December 2009 the CROES (Clinical Research Office of the Endourological Society) collected data on consecutive patients at 96 centers globally. Patients were evaluated for stone-free status using plain x-ray of the kidneys, ureters and bladder. Treatment success was defined as no visible stones or residual fragments less than 4 mm. Multivariate regression was used to model the relationship between preoperative descriptors and the stone-free rate. Variables included case load, prior treatment, body mass index, staghorn stones, renal anomalies, and stone burden, location and count. Bootstrapping techniques were used to validate the model. Adjusted chi-square statistic values were used to rank the prognostic value of variables. A nomogram was developed using significant predictors from the model. We assessed the predictive accuracy of the nomogram using the ROC curve AUC. The nomogram was calibrated. RESULTS: Stone burden was the best predictor of the stone-free rate (chi-square = 30.27, p <0.001). Other factors associated with the stone-free rate were case volume (chi-square = 35.75, p <0.001), prior stone treatment (chi-square = 14.55, p <0.012), staghorn stone (adjusted chi-square = 4.73, p <0.029), stone location (chi-square = 14.74, p <0.001) and stone count (chi-square = 4.78, p <0.004). A nephrolithometric nomogram was developed with predictive accuracy (AUC 0.76). CONCLUSIONS: The percutaneous nephrolithotomy stone-free rate can be predicted using preclinical data and radiological information. We present a nephrolithometric nomogram for percutaneous nephrolithotomy.

Risks and Benefits of Postoperative Double-J Stent Placement After Ureteroscopy: Results from the Clinical Research Office of Endourological Society Ureteroscopy Global Study.

PURPOSE: Double-J stent placement after stone removal by ureteroscopy (URS) is common and recommended in many cases but debatable in others. In this study, the risks and benefits of postoperative Double-J stent placement in URS stone treatment procedures undertaken in current clinical practice are examined. MATERIALS AND METHODS: The Clinical Research Office of Endourological Society (CROES) URS is a prospective, observational, international multicenter study, in which patients are candidates for URS as primary treatment or after failure of prior treatment for ureteral and renal stones. Baseline, intraoperative, and postoperative data were collected. Predictors and outcomes of postoperative stent placement were analyzed by inverse probability-weighted regression adjustment of the relationship between a Double-J stent placement and outcomes (complications, readmission [including retreatment], and length of hospital stay). RESULTS: Significant predictors of postoperative Double-J stent placement in URS treatment of ureteral stones were intraoperative complications, impacted stones, operation time, stone burden, age, presence of a solitary kidney, and stone-free rate. In renal stone treatment, the predictors identified included operation time, age, preoperative stent placement, anticoagulant use, presence of a solitary kidney, and intraoperative complications. In both ureteral and renal stone treatment groups, postoperative placement of a Double-J stent resulted in significantly fewer postoperative complications (p < 0.001) compared with patients who did not receive a stent. CONCLUSIONS: Patient- and procedure-related variables were identified, which may enable an individualized approach to postoperative stenting, resulting in improved clinical outcomes in urologic stone treatment by URS.

Impact of case volumes on the outcomes of percutaneous nephrolithotomy.

BACKGROUND: Previous studies have demonstrated relationships between case volumes and outcomes in surgery. Little is known about the impact of case volumes on the outcomes of percutaneous nephrolithotomy (PCNL). OBJECTIVE: To investigate the influence of case volumes on the efficacy and safety outcomes of PCNL. DESIGN, SETTING, AND PARTICIPANTS: From November 2007 to December 2009, prospective data were collected by the Clinical Research Office of the Endourological Society from consecutive patients over a 1-yr period in 96 centers globally. Data of 3933 patients in the Global PCNL study database were included in this study. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Patients were divided into low- and high-volume groups based on the median annual case volume of their respective treatment center. Preoperative characteristics and outcomes were compared between the two groups. Case volume was treated as a continuous variable. The relationship between case volume and stone-free (SF) rate, complication rate, and duration of hospital stay was explored using multivariate regression analysis. RESULTS AND LIMITATIONS: SF rates were higher in high-volume centers (82.5% vs 75.1%; p value <0.001). Complication rates were lower in high-volume centers (15.9% vs 21.7%; p value 0.002), whereas the mean (standard deviation [SD]) duration of stay was shorter in high-volume centers (3.4 [2.6] vs 4.9 [3.7] d; p value <0.001). SF rate increased with case volume, whereas complication rate and duration of stay diminished with increasing case volumes after adjusting for stone burden, urine culture status, American Society of Anesthesiologists score, and the presence of staghorn stones. The highest SF rates were observed in centers with >120 cases per year. CONCLUSIONS: Centers that perform high numbers of PCNLs per year achieve better results. Both the efficacy and safety outcomes of PCNL improve with the number of surgeries performed in a given center per year.

Prospective comparison of outcomes of percutaneous nephrolithotomy in elderly patients versus younger patients.

PURPOSE: The purpose of the study was to prospectively compare operative and postoperative characteristics and outcomes in elderly patients undergoing percutaneous nephrolithotomy (PCNL) compared with younger patients. PATIENTS AND METHODS: Prospectively collected data from the Clinical Research Office of the Endourological Society (CROES) Global PCNL Study database were used. Elderly patients were defined as those aged 70 years and above, while younger patients were those between 18 and 70 years of age. Matched and unmatched group comparisons were performed based on imaging modality used for assessing stone-free status. Patient characteristics, operative data, and postoperative outcomes were compared. RESULTS: The median age of the elderly group vs the young group was 74 years (range 70-93 years) vs 49 years. In the unmatched analysis, staghorn stones were seen at higher rates in the elderly group (27.8% vs 21.8%, P=0.014); however, the mean stone size was not significantly different (465.0 vs 422.8, P=0.063). The length of hospitalization was significantly longer in the elderly group compared with the young group in the unmatched analysis (5 days vs 4.1 days, P<0.001). The same difference was not apparent in the matched analysis (5.0 days vs 4.4 days, P=0.288). Overall complication rates were not significantly different in the unmatched analysis. In the matched analysis, however, a statistically significant higher rate of overall complications was seen. Stone-free rates were similar among all groups. CONCLUSION: PCNL in elderly patients over the age of 70 years produces results comparable to those seen in younger patients. With only a slightly higher-be it statistically significant-complication rate, the stone-free rate in older patients was the same as in the younger group.

The percutaneous nephrolithotomy global study: classification of complications.

PURPOSE: This study evaluated postoperative complications of percutaneous nephrolithotomy (PCNL) and the influence of selected factors on the risk of complications using the Clinical Research Office of the Endourological Society (CROES) PCNL Global Study database. PATIENTS AND METHODS: The CROES PCNL Global Study collected prospective data for consecutive patients who were treated with PCNL at centers around the world for 1 year. Complications were evaluated by the modified Clavien classification system. RESULTS: Of 5724 patients with Clavien scores, 1175 (20.5%) patients experienced one or more complications. The most frequent complications were fever and bleeding. Urinary leakage, hydrothorax, hematuria, urinary tract infection, pelvic perforation, and urinary fistula also occurred in ≥20 patients in each group. The majority of complications (n=634, 54.0%) were classified as Clavien grade I. Two patients died in the postoperative period. The largest absolute increases in mean Clavien score were associated with American Society of Anesthesiologists (ASA) physical status classification IV (0.75) or III (0.34), anticoagulant medication use (0.29), positive microbiologic culture from urine (0.24), and the presence of concurrent cardiovascular disease (0.15). Multivariate regression analysis revealed that operative time and ASA score were significant predictors of higher mean Clavien scores. CONCLUSION: The majority of complications after PCNL are minor. Longer operative time and higher ASA scores are associated with the risk of more severe postoperative complications in PCNL.