title: Impact of case volumes on the outcomes of percutaneous nephrolithotomy.
abstract: 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.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Urology, AMC University Hospital, Amsterdam, The Netherlands.
authors.forename: Dedan
authors.initials: D
authors.lastname: Opondo
authors.forename: Ahmet
authors.initials: A
authors.lastname: Tefekli
authors.forename: Tarik
authors.initials: T
authors.lastname: Esen
authors.forename: Gaston
authors.initials: G
authors.lastname: Labate
authors.forename: Kandasami
authors.initials: K
authors.lastname: Sangam
authors.forename: Antonello
authors.initials: A
authors.lastname: De Lisa
authors.forename: Hemendra
authors.initials: H
authors.lastname: Shah
authors.forename: Jean
authors.initials: J
authors.lastname: de la Rosette
mesh_terms: D005260:Female; D061847:Hospitals, High-Volume; D061846:Hospitals, Low-Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000706:statistics & numerical data*; D017063:Outcome Assessment, Health Care; D011446:Prospective Studies