Emergency transport and interhospital transfer in STsegment elevation myocardial infarction

1
Emergency transport and inter-hospital transfer
in ST-segment elevation myocardial infarction

• Thomas W. Concannon, MA1,
• David M. Kent MD MS2, Sharon-Lise Normand PhD3,
• Joseph P. Newhouse PhD3, Robin Ruthazer MPH2,
• John L Griffith PhD2, Joni R. Beshansky RN MPH2,
• John B. Wong, MD PhD2, Harry P. Selker MD MSPH2
• Funded by the Agency for Healthcare Research and
  Quality (RO1 HS010282 and T32 HS00060-12)
• PhD Program in Health Policy, Harvard University
• Institute for Clinical Research and Health Policy
  Studies, Tufts-New England Medical Center
• Division of Health Care Policy Research and
  Education, Harvard Medical School

2
Background
Heart attack may be caused by the formation of a
blood clot that blocks normal blood flow to heart
muscle

• ST-segment elevation myocardial infarction
  (STEMI)

3
Background

• May be treated with
• Angioplasty, involving the insertion of a
  catheter into the affected blood vessel and
  inflation of a balloon to manually clear the clot
• Thrombolytic therapy, involving the
  administration of a clot-busting drug

4
Background

• Angioplasty can only be performed in specialized
  hospital settings
• Thrombolysis can be performed in any hospital
  emergency department

5
Background Thrombolysis or Angioplasty?

• Angioplasty yields superior outcomes in average
  30-day mortality and in other clinical endpoints
• However, thrombolysis remains the standard of
  care in most settings

6
Background - Study Question

• What is the impact on mortality of targeting
  angioplasty to high benefit patients?

7
Methods - Objective

• Evaluate 3 Policy Options
• Closest Hospital Policy
• Transport to closest hospital, treat with
  locally available therapy
• Universal Angioplasty Policy
• Transport to closest angioplasty-capable
  hospital, treat with angioplasty
• Targeted Angioplasty Policy
• Transport to closest hospital, evaluate, treat
  locally or transfer for angioplasty

8
Methods - Outcomes of Interest

• Primary Outcome
• Patient 30 day mortality
• Secondary Outcome
• Hospital volume

9
Methods - Predictive Model

• Recently developed and validated predictive
  instrument
• Predicts 30-day mortality with angioplasty and
  with thrombolysis
• Easily obtainable characteristics of patients
• Incorporated onto the output of an EKG

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Methods - Predictive Model
11.3
Probability of 30-day mortality with thrombolysis
11
Methods - Predictive Model
7.3
Probability of 30-day mortality with angioplasty
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Methods - Predictive Model
149 minutes
Maximum time delay at which the benefit with
angioplasty disappears
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Methods Simulation Model

• C-PORT Patient 183
• Age 79
• Systolic blood pressure 116
• No history of diabetes
• Moderately severe heart attack
• 93 minutes from symptom onset to Emergency
  Department arrival

Location Census block 2010 Time Monday at
330 am
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Closest Hospital Policy
Methods
Treated with thrombolysis Probability of death
.095
503 am
Monday 330 am
93 minutes
15
Universal Angioplasty Policy
Methods
525 am
115 minutes
Treated with angioplasty Probability of death
.0733
Monday 330 am
16
Targeted Angioplasty Policy
Methods
531 am
28 minutes
Treated with angioplasty Probability of death
.0738
Monday 330 am
93 minutes
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Results - 30-Day Mortality
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Results - Hospital Volumes Closest Hospital Policy

Full-time
Part-time
No Angioplasty
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Results - Hospital Volumes Universal Angioplasty
Policy

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Results - Hospital Volumes Targeted Angioplasty
Policy

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Results - Summary

• A policy of targeting angioplasty to high
  benefit patients could capture much or all of the
  procedures potential benefit while avoiding
  dramatic effects on hospital volumes

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Conclusions

• Inter-patient variation in the risks and benefits
  of angioplasty may be an important factor in
  decisions about the appropriate course of
  treatment.
• More information is needed on how this variation
  affects the tradeoff between early treatment and
  specialized treatment
• Further study is needed to determine the best
  approach for allocating angioplasty