title: Hospital Volume Does Not Influence the Safety of Percutaneous Nephrolithotomy in England: A Population-Based Cohort Study.
abstract: OBJECTIVE
  This study aims to investigate the relationship between hospital case volume and safety-related outcomes after percutaneous nephrolithotomy (PCNL) within the English National Health Service (NHS).
  
  
  METHODS
  The study used the Hospital Episode Statistics (HES) database, a routine administrative database, recording information on operations, comorbidity, and outcomes for all NHS hospital admissions in England. Records for all patients undergoing an initial PCNL between April 1, 2006 and March 31, 2012 were extracted. NHS trusts were divided into low-, medium-, and high-volume groups, according to the average annual number of PCNLs performed. We used multiple regression analyses to examine the associations between hospital volume and outcomes incorporating risk adjustment for sex, age, comorbidity, and hospital teaching status. Postoperative outcomes included: Emergency readmission, infection, and hemorrhage. Mean length of stay was also measured.
  
  
  RESULTS
  There were 7661 index elective PCNL procedures performed in 163 hospital trusts, between April 2006 and March 2012. There were 2459 patients who underwent PCNL in the 116 units performing fewer than 10 PCNL procedures per year; 2643 patients in the 37 units performing 10 to 19 procedures per year; and 2459 patients in the 9 hospitals performing more than 20 procedures per year. For low-, medium-, and high-volume trusts, there was little variation in the rates of emergency readmission (L 9.7%, M 9.3%, H 8.4%), infection (3.0%, 4.2%, 3.8%), or hemorrhage (1.3%, 1.5%, 1.5%), and there was no statistical evidence that volume was associated with adjusted outcomes. Mean length of stay was slightly shorter in the medium- (5.0 days) and high-volume (5.0) groups compared with the low-volume group (5.3). The effect remained statistically significant after adjusted for confounding.
  
  
  CONCLUSIONS
  Hospital volume was not associated with emergency readmission, infection, or hemorrhage. Length of stay appears to be shorter in higher volume units.
authors.affiliation: 1 Clinical Effectiveness Unit, Royal College of Surgeons , London, United Kingdom .
authors.forename: John M
authors.initials: JM
authors.lastname: Withington
authors.affiliation: 2 Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine , London, United Kingdom .
authors.forename: Susan C
authors.initials: SC
authors.lastname: Charman
authors.affiliation: 3 Department of Urology, Cambridge University Hospitals NHS Foundation Trust , Cambridge, United Kingdom .
authors.forename: James N
authors.initials: JN
authors.lastname: Armitage
authors.affiliation: 2 Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine , London, United Kingdom .
authors.forename: David
authors.initials: D
authors.lastname: Cromwell
authors.affiliation: 4 Department of Urology, Norfolk and Norwich University Hospital NHS Foundation Trust , Norwich, United Kingdom .
authors.forename: William D
authors.initials: WD
authors.lastname: Finch
authors.affiliation: 5 Department of Urology, Addenbrooke's Hospital, Cambridge, United Kingdom .
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: Wiseman
authors.affiliation: 4 Department of Urology, Norfolk and Norwich University Hospital NHS Foundation Trust , Norwich, United Kingdom .
authors.forename: Stuart
authors.initials: S
authors.lastname: Irving
authors.affiliation: 6 Department of Urology, Guy's and St Thomas' Hospitals NHS Trust , London, United Kingdom .
authors.forename: Jonathan
authors.initials: J
authors.lastname: Glass
authors.affiliation: 4 Department of Urology, Norfolk and Norwich University Hospital NHS Foundation Trust , Norwich, United Kingdom .
authors.forename: Neil A
authors.initials: NA
authors.lastname: Burgess
mesh_terms: D000368:Aged; D015331:Cohort Studies; D016208:Databases, Factual; D004739:England; D005260:Female; D006761:Hospitals / Q000706:statistics & numerical data; D061847:Hospitals, High-Volume / Q000592:standards / Q000706:statistics & numerical data; D061846:Hospitals, Low-Volume / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000706:statistics & numerical data*; D010359:Patient Readmission / Q000706:statistics & numerical data; D061214:Patient Safety / Q000706:statistics & numerical data*; D012044:Regression Analysis