Informed consent during the clinical emergency of acute myocardial infarction (HERO-2 consent substudy): a prospective observational study

Lancet. 2003 Mar 15;361(9361):918-22. doi: 10.1016/s0140-6736(03)12773-0.


Background: Anxiety, fear, pain, and treatment with morphine might compromise the ability of patients to comprehend information about, and give informed consent for, participation in clinical trials. We aimed to assess whether patients with acute myocardial infarction could understand written and verbal information and whether they were competent to give autonomous informed consent to participate in a clinical trial.

Methods: We prospectively studied 399 patients with acute myocardial infarction in 16 hospitals in New Zealand and Australia who were eligible for participation in the Hirulog and Early Reperfusion or Occlusion (HERO)-2 trial. We assessed readability of patient information sheets, patients' educational status, their views of the consent process, comprehension of verbal and written information, and competence to give consent.

Findings: The patient information sheet needed a year 13 (age 18) educational level for comprehension, although only 75 of 345 patients (22%) had been educated beyond secondary school. Only 63 of 346 (18%) read the patient information sheet before giving or refusing consent to participate. Patients who gave consent were more likely to report good or partial comprehension of the information provided than were those who refused consent (272 [89%] vs 14 [70%], respectively; p=0.009). In an assessment of competence to make an autonomous decision, 75 of 145 (52%) were ranked at the lowest grade and 26 (18%) were not competent to consent.

Interpretation: Although the consent process for HERO-2 met regulatory requirements for clinical trials, it was inappropriate for the needs of most patients. The patients' comprehension of the information provided and their competence to autonomously give consent was less than optimum.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Antithrombins / therapeutic use
  • Australia
  • Educational Status
  • Female
  • Humans
  • Informed Consent*
  • Male
  • Mental Competency / classification*
  • Middle Aged
  • Myocardial Infarction / drug therapy
  • Myocardial Infarction / psychology*
  • New Zealand
  • Prospective Studies
  • Randomized Controlled Trials as Topic


  • Antithrombins