title: Relation between hospital intra-aortic balloon counterpulsation volume and mortality in acute myocardial infarction complicated by cardiogenic shock.
abstract: BACKGROUND
  Increasing evidence suggests an inverse relationship between outcome and the total number of invasive cardiac procedures performed at a given hospital. The purpose of the present study was to determine if a similar relationship exists between the number of intra-aortic balloon counterpulsation (IABP) procedures performed at a given hospital per year and the in-hospital mortality rate of patients with acute myocardial infarction complicated by cardiogenic shock.
  
  
  RESULTS
  We analyzed data of 12 730 patients at 750 hospitals enrolled in the National Registry of Myocardial Infarction 2 from 1994 to 1998. The hospitals were divided into tertiles (low-, intermediate-, and high-IABP volume hospitals) according to the number of IABPs performed at the given hospital per year. The median number of IABPs performed per hospital per year was 3.4, 12.7, and 37.4 IABPs at low-, intermediate-, and high-volume hospitals, respectively. Of those patients who underwent IABP, there were only minor differences in baseline patient characteristics between the 3 groups. Crude mortality rate decreased with increasing IABP volume: 65.4%, lowest volume tertile; 54.1%, intermediate volume tertile; and 50.6%, highest volume tertile (P for trend <0.001). This mortality difference represented 150 fewer deaths per 1000 patients treated at the high IABP hospitals. In the multivariate analysis, high hospital IABP volume for patients with acute myocardial infarction was associated with lower mortality (OR=0.71, 95% CI=0.56 to 0.90), independent of baseline patient characteristics, hospital factors, treatment, and procedures such as PTCA.
  
  
  CONCLUSIONS
  Among the myocardial infarction patients with cardiogenic shock who underwent IABP placement, mortality rate was significantly lower at high-IABP volume hospitals compared with low-IABP volume hospitals.
authors.affiliation: Division of Cardiology, Kaiser Permanente Medical Group, Inc, Richmond, CA 94801-3195, USA.
authors.forename: Edmond W
authors.initials: EW
authors.lastname: Chen
authors.forename: John G
authors.initials: JG
authors.lastname: Canto
authors.forename: Lori S
authors.initials: LS
authors.lastname: Parsons
authors.forename: Eric D
authors.initials: ED
authors.lastname: Peterson
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Littrell
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Every
authors.forename: C Michael
authors.initials: CM
authors.lastname: Gibson
authors.forename: Judith S
authors.initials: JS
authors.lastname: Hochman
authors.forename: E Magnus
authors.initials: EM
authors.lastname: Ohman
authors.forename: Morris
authors.initials: M
authors.lastname: Cheeks
authors.forename: Hal V
authors.initials: HV
authors.lastname: Barron
mesh_terms: D000208:Acute Disease; D000368:Aged; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007423:Intra-Aortic Balloon Pumping / Q000706:statistics & numerical data*; D008297:Male; D009203:Myocardial Infarction / Q000401:mortality* / Q000503:physiopathology; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D012042:Registries / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012770:Shock, Cardiogenic / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy; D014481:United States / Q000453:epidemiology