title: Intensive care units with low versus high volume of myocardial infarction: clinical outcomes, resource utilization, and quality metrics.
abstract: BACKGROUND
  The volume-outcome relationship associated with intensive care unit (ICU) experience with managing acute myocardial infarction (AMI) remains inadequately understood.
  
  
  RESULTS
  Within a multicenter clinical ICU database, we identified patients with a primary ICU admission diagnosis of AMI between 2008 and 2010 to evaluate whether annual AMI volume of an individual ICU is associated with mortality, length-of-stay, or quality indicators. Patients were categorized into those treated in ICUs with low-annual-AMI volume (≤50th percentile, <2 AMI patients/month, n=569 patients) versus high-annual-AMI volume (≥90th percentile, ≥8 AMI patients/month, n=17 553 patients). Poisson regression and generalized estimating equation with negative binomial regression were used to calculate the relative risk (95% CI) for mortality and length-of-stay, respectively, associated with admission to a low-AMI-volume ICU. When compared with high-AMI-volume, patients admitted to low-AMI-volume ICUs had substantially more medical comorbidities, higher in-hospital mortality (11% versus 4%, P<0.001), longer hospitalizations (6.9±7.0 versus 5.0±5.0 days, P<0.001), and fewer evidence-based therapies for AMI (reperfusion therapy, antiplatelets, β-blockers, and statins). However, after adjustment for baseline patient characteristics, low-AMI-volume ICU was no longer an independent predictor of in-hospital mortality (relative risk 1.17 [0.87 to 1.56]) or hospital length-of-stay (relative risk 1.01 [0.94 to 1.08]). Similar findings were noted in secondary analyses of ICU mortality and ICU length-of-stay.
  
  
  CONCLUSIONS
  Admission to an ICU with lower annual AMI volume is associated with higher in-hospital mortality, longer hospitalization, and lower use of evidence-based therapies for AMI. However, the relationship between low-AMI-volume and outcomes is no longer present after accounting for the higher-risk medical comorbidities and clinical characteristics of patients admitted to these ICUs.
authors.affiliation: Mercy Heart and Vascular, Washington, MO (J.M.S.) Saint Louis University, St Louis, MO (J.M.S., A.N.).
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Stolker
authors.affiliation: Philips Healthcare, Baltimore, MD (O.B.) University of Maryland School of Pharmacy, Baltimore, MD (O.B., C.S.F., V.D.H.).
authors.forename: Omar
authors.initials: O
authors.lastname: Badawi
authors.affiliation: Saint Luke's Mid America Heart and Vascular Institute, Kansas City, MO (J.A.S., K.F.K., P.S.C.).
authors.forename: John A
authors.initials: JA
authors.lastname: Spertus
authors.affiliation: Saint Louis University, St Louis, MO (J.M.S., A.N.).
authors.forename: Ammar
authors.initials: A
authors.lastname: Nasir
authors.affiliation: Saint Luke's Mid America Heart and Vascular Institute, Kansas City, MO (J.A.S., K.F.K., P.S.C.).
authors.forename: Kevin F
authors.initials: KF
authors.lastname: Kennedy
authors.affiliation: IMPAQ International, Columbia, MD (I.H.H.).
authors.forename: Ilene H
authors.initials: IH
authors.lastname: Harris
authors.affiliation: University of Maryland School of Pharmacy, Baltimore, MD (O.B., C.S.F., V.D.H.).
authors.forename: Christine S
authors.initials: CS
authors.lastname: Franey
authors.affiliation: University of Maryland School of Pharmacy, Baltimore, MD (O.B., C.S.F., V.D.H.).
authors.forename: Van Doren
authors.initials: VD
authors.lastname: Hsu
authors.affiliation: Midwest Pulmonary Consultants, Kansas City, MO (G.R.R., G.H.H., V.M.L.).
authors.forename: Gary R
authors.initials: GR
authors.lastname: Ripple
authors.affiliation: Midwest Pulmonary Consultants, Kansas City, MO (G.R.R., G.H.H., V.M.L.).
authors.forename: Gregory H
authors.initials: GH
authors.lastname: Howell
authors.affiliation: Midwest Pulmonary Consultants, Kansas City, MO (G.R.R., G.H.H., V.M.L.).
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Lem
authors.affiliation: Saint Luke's Mid America Heart and Vascular Institute, Kansas City, MO (J.A.S., K.F.K., P.S.C.).
authors.forename: Paul S
authors.initials: PS
authors.lastname: Chan
mesh_terms: D000368:Aged; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units / Q000592:standards* / Q000706:statistics & numerical data; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality / Q000628:therapy*; D017410:Practice Guidelines as Topic; D011787:Quality of Health Care / Q000592:standards / Q000706:statistics & numerical data; D012306:Risk; D016896:Treatment Outcome
keywords: acute myocardial infarction; intensive care unit; outcomes research; quality of care; volume‐outcome relationship