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Intensive care use and mortality among patients with ST elevation myocardial infarction: retrospective cohort study

BMJ 2019; 365 doi: https://doi.org/10.1136/bmj.l1927 (Published 04 June 2019) Cite this as: BMJ 2019;365:l1927
  1. Thomas S Valley, assistant professor1 2 3,
  2. Theodore J Iwashyna, professor1 2 4,
  3. Colin R Cooke, associate professor1 2 5,
  4. Shashank S Sinha, director6 7,
  5. Andrew M Ryan, associate professor2 5,
  6. Robert W Yeh, associate professor8 9,
  7. Brahmajee K Nallamothu, professor2 4 5 10
  1. 1Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
  2. 2Institute for Healthcare Policy and Innovation, University of Michigan, Ann Arbor, MI, USA
  3. 3Center for Bioethics and Social Sciences in Medicine, University of Michigan, Ann Arbor, MI, USA
  4. 4VA Center for Clinical Management Research, Ann Arbor, MI, USA
  5. 5Center for Health Outcomes and Policy, University of Michigan, Ann Arbor, MI, USA
  6. 6Cardiac Intensive Care Unit, Inova Heart and Vascular Institute, Inova Fairfax Medical Center, Falls Church, VA, USA
  7. 7Cardiovascular Critical Care Research, Inova Heart and Vascular Institute, Inova Fairfax Medical Center, Falls Church, VA, USA
  8. 8Richard and Susan Smith Center for Outcomes Research in Cardiology, Beth Israel Deaconess Medical Center, Boston, MA, USA
  9. 9Department of Medicine, Harvard Medical School, Boston, MA, USA
  10. 10Division of Cardiovascular Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
  1. Correspondence to: T Valley valleyt{at}umich.edu or @tsvalley on Twitter
  • Accepted 16 April 2019

Abstract

Objective To evaluate the effect of intensive care unit (ICU) admission on mortality among patients with ST elevation myocardial infarction (STEMI).

Design Retrospective cohort study.

Setting 1727 acute care hospitals in the United States.

Participants Medicare beneficiaries (aged 65 years or older) admitted with STEMI to either an ICU or a non-ICU unit (general/telemetry ward or intermediate care) between January 2014 and October 2015.

Main outcome measure 30 day mortality. An instrumental variable analysis was done to account for confounding, using as an instrument the additional distance that a patient with STEMI would need to travel beyond the closest hospital to arrive at a hospital in the top quarter of ICU admission rates for STEMI.

Results The analysis included 109 375 patients admitted to hospital with STEMI. Hospitals in the top quarter of ICU admission rates admitted 85% or more of STEMI patients to an ICU. Among patients who received ICU care dependent on their proximity to a hospital in the top quarter of ICU admission rates, ICU admission was associated with lower 30 day mortality than non-ICU admission (absolute decrease 6.1 (95% confidence interval −11.9 to −0.3) percentage points). In a separate analysis among patients with non-STEMI, a group for whom evidence suggests that routine ICU care does not improve outcomes, ICU admission was not associated with differences in mortality (absolute increase 1.3 (−0.9 to 3.4) percentage points).

Conclusions ICU care for STEMI is associated with improved mortality among patients who could be treated in an ICU or non-ICU unit. An urgent need exists to identify which patients with STEMI benefit from ICU admission and what about ICU care is beneficial.

Footnotes

  • Contributors: TSV and BKN were responsible for study concept and design. TSV obtained funding. TSV and CRC acquired the data, and all authors were involved in analysis and interpretation of data. TSV and BKN drafted the manuscript, and all authors revised it critically for important intellectual content. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. TSV is the guarantor.

  • Funding: This work was supported by NIH K23 HL140165 (TSV), K12 HL138039 (TJI), and R01 HL137816 (CRC). The funding organizations had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organization for the submitted work other than that described above; no financial relationships with any organizations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: The Institutional Review Board for the University of Michigan approved the study and provided a waiver of consent (HUM00053488).

  • Data sharing: The statistical code for the analyses is included in the supplementary materials. Additional code can be obtained from the corresponding author on request. Medicare data are not publicly available but can be obtained through the Center for Medicare and Medicaid Services.

  • Transparency: The lead author affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

  • Disclaimer: This manuscript does not necessarily represent the views of the US Government or the Department of Veterans Affairs.

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