Myocardial infarction: low admission hospitals had increased mortality rates.

Clinical bottom line (level 1b)

  1. Patients who had a myocardial infarction at home were at an increased risk of 30 day mortality if they were admitted to a hospital which has a low volume (<0.8 patients/week) of infarct admissions.
  2. A sixth of patients who had a myocardial infarction at home were dead at 30 days.
Thiemann et al: New England Journal of Medicine 1999; 340 (21): 1640-1648
Expires March 2003

The study

Retrospective cohort study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: acute care hospitals, USA

98898 patients (aged mean 76 years, 53% male) acute myocardial infarction admitted from home with a verified infarction present on admission

Excluded if
  • <65 years
  • duplicate admissions
  • interhospital transfers
  • admissions from nursing and retirements homes
  • infarctions occurred after admission
  • referred from physicians' offices and free-standing clinics
  • coma on arrival
  • preexisting dementia
  • terminal illness
  • from five states with intentional under sampling unrelated to other projects



    • Factors studied:
  • Age, race, symptom duration, previous history of CCF, CABG, MI, COPD, DM, PVD, stroke , cigarette smoking, blood pressure, respiratory rate, S3 on admission, CPR <48h previous to admission, levels of albumin, urea and creatinine, ST elevation, conduction abnormalities, mobility status, thrombolytic therapy, area of residence (rural, metropolitan or urban) geographic region, speciality of attending physician and access to invasive procedures
  • hospital volume (per decrease of 5.5 patients/week)
  • no angiography available compared with angiography and CABG on site




    • Multivariate analysis was used to adjust for confounding factors. There was no collinearity in the factors (Spearman correlations <0.5)

    100% followed for 30 days
    Outcomes studied:
  • death

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    death 30 days 15109/98898 15.3%
    (15.1% to 15.5%)

    prognostic factor for
    death     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    hospital volume (per decrease of 5.5 patients/week) 30 days 1.10
    (1.05 to 1.16)     		60
    (38 to 120)
    no angiography available compared with angiography and CABG on site 30 days 1.02
    (0.96 to 1.08)     		-300
    (-75 to 150)

    Comments

    1. The availability of access to invasive procedures did not affect survival rates in this observational study.

    Citation

    1. Thiemann DR, Coresh J, Oetgen WJ, et al: The association between hospital volume and survival after acute myocardial infarction in elderly patients. New England Journal of Medicine 1999; 340 (21): 1640-1648
    Contributor: Clare Wotton and Bob Phillips, January 2000
    Reviewer: Daniel Sontheimer

    Clinical Question.
    Patient myocardial infarction
    Intervention or Exposure hospital with high volume of patients
    Comparison hospital with low volume
    Outcome death