Unstable angina: determining patient's risk helps to predict need for intensive care.

Clinical bottom line (level 1a)

  1. A sixth of patients with acute chest pain who are in a high risk group will have a first major event (requiring admission to intensive care) within 72 hours.
  2. A twelfth of patients in a moderate risk group will have a first major event within 72 hours.
  3. A twenty-fifth of patients in a low risk group will have a first major event within 72 hours.
  4. Less than 1% of patients in a very low risk group will have a first major event within 72 hours.
Goldman et al: New England Journal of Medicine 1996; 334: 1498-1504
Expires March 2003

The study

Inception cohort study with objective outcomes, adjusted for confounding factors, validated in an independent set of patients.

Setting: one hospital emergency department, USA

4676 patients (aged over 60y in 44% cases, 49% male) primary symptom of chest pain unexplained by obvious local trauma or abnormalities on the chest radiograph

Excluded if
  • cardiac arrest
  • left against medical advice
  • insufficiently explicit interpretation of ECG




Data was validated using the chi-square test for association and the Mantel-Haenszel stratified test. The area under the receiver-operating-characteristic curve (measure of overall discrimination) was calculated and compared for various predictive models.

100% followed for 72 hours
Outcomes studied:
  • rate of first major event in high risk group (defined as those thought on a clinical basis to require intensive care)
  • rate of first major event with moderate risk
  • rate of first major event with low risk
  • rate of first major event with very low risk

  • Patients were assigned to one of four groups according to the risk of an event within 24 hours, from very low (0.3%) to high (16%). Five factors were used to assign patients to a risk group:
    • electrocardiographic evidence of an ST elevation or Q waves, not known to be old, in two or more leads
    • ST segment or T wave changes, not known to be old, indicative of myocardial ischaemia
    • pain worse than prior angina or the same as the pain associated with a prior myocardial infarction
    • systolic blood pressure <110 mmHg
    • rales above the bases bilaterally
    Patients were classified as:
    • high risk: suspected MI on ECG or suspected ischaemia on ECG plus two or more risk factors
    • moderate risk: suspected ischaemia on ECG and no or one risk factor
    • low risk: just one risk factor (no MI or ischaemia)
    • very low risk: no risk factor

The evidence

outcome time to outcome number of patients/total number %
(95% CI)
rate of first major event in high risk group 72 hours 51/317 16.1%
(12.0% to 20.1%)
rate of first major event with moderate risk 72 hours 66/845 7.81%
(6.00% to 9.62%)
rate of first major event with low risk 72 hours 36/918 3.92%
(2.67% to 5.18%)
rate of first major event with very low risk 72 hours 15/2596 0.58%
(0.29% to 0.87%)

Comments

  1. This study reinforces the utility of inexpensive "low technology" measures, namely--history, physical exam, and ECG to provide important prognostic data in patients being evaluated for chest pain.
  2. The derivation group of 10,682 patients were enrolled from seven emergency departments.

Citation

  1. Goldman L, Cook F, Johnson PA, et al: Prediction of the need for intensive care in patients who come to emergency departments with acute chest pain. New England Journal of Medicine 1996; 334: 1498-1504
Contributor: Clare Wotton and Bob Phillips, January 2000
Reviewer: Arnold Baas

Clinical Question.
Patient acute chest pain
Intervention or Exposure high risk, clinical and ECG factors
Comparison low risk
Outcome major event