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

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.