title: Effect of procedure volume on outcomes after iliac artery angioplasty and stenting.
abstract: BACKGROUND
  Service reorganization to concentrate complex vascular services in hospitals with high caseload volume aims to reduce mortality and complication rates. The present study assessed the relationship between caseload volume and outcome for iliac artery angioplasty and stenting in England using a routinely available national data set (Hospital Episode Statistics, HES).
  
  
  METHODS
  Routine administrative data for iliac artery angioplasty and stent procedures performed in England between 2007 and 2011 were analysed. Associations between centre volume and outcomes (death, complications and duration of hospital stay) were tested and compared for two methods of stratification (quartiles and quintiles) and two statistical tests (odds ratios and the Cochran-Armitage test for trend). Multivariable analysis was also performed.
  
  
  RESULTS
  There were 23,308 episodes of care recorded in HES with Office of Population Censuses and Surveys Classification of Surgical Operations and Procedures, fourth revision, codes L54.1 or L54.4 corresponding to iliac artery intervention. There was a gradual increase year by year in number of procedures performed. Univariable and multivariable analysis showed no association between centre volume and either death or complications (multivariable odds ratio, OR 1.00, 95 per cent confidence interval 1.00 to 1.00) for elective and non-elective procedures. Age was associated with higher mortality and complication rates in elective procedures, and with mortality in non-elective procedures. The risk of death after elective iliac angioplasty or stenting was significantly higher in women (multivariable OR 4.98, 2.09 to 13.26).
  
  
  CONCLUSIONS
  There was no association between the outcomes of endovascular iliac artery intervention and centre volume, but outcomes were significantly worse with increasing age and female sex.
authors.affiliation: Sheffield Vascular Institute, Northern General Hospital, Sheffield, UK. s.goode@sheffield.ac.uk
authors.forename: S D
authors.initials: SD
authors.lastname: Goode
authors.forename: K
authors.initials: K
authors.lastname: Keltie
authors.forename: J
authors.initials: J
authors.lastname: Burn
authors.forename: H
authors.initials: H
authors.lastname: Patrick
authors.forename: T J
authors.initials: TJ
authors.lastname: Cleveland
authors.forename: B
authors.initials: B
authors.lastname: Campbell
authors.forename: P
authors.initials: P
authors.lastname: Gaines
authors.forename: A J
authors.initials: AJ
authors.lastname: Sims
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017130:Angioplasty / Q000009:adverse effects / Q000706:statistics & numerical data*; D017558:Elective Surgical Procedures / Q000706:statistics & numerical data; D004638:Emergency Treatment / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007083:Iliac Artery / Q000601:surgery*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D058729:Peripheral Arterial Disease / Q000601:surgery*; D015607:Stents / Q000009:adverse effects / Q000706:statistics & numerical data*; D016896:Treatment Outcome; D016526:Workload / Q000706:statistics & numerical data*; D055815:Young Adult