Informed consent: how much does the patient understand?

Clin Pharmacol Ther. 1980 Apr;27(4):435-40. doi: 10.1038/clpt.1980.60.


Comprehension and recall of the information contained in the informed consent statement was tested in clinically hypertensive patients entering a controlled trial comparing hydrochlorothiazide and propranolol. The consent statement was the primary vehicle for conveying the information to the patient. The average of correct answers to a multiple-choice quiz was 71.6% at 2 hr and 61.2% at 3 mo after the consent procedure. The effectiveness of recall did not correlate with level of education. Patients exhibited greater comprehension of the action of the drugs than of their side effects. Nearly all patients indicated their belief that they would receive the best possible care. While 95% wanted to be informed about the trial, 75% stated they would have given their consent even without this information.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Clinical Trials as Topic
  • Comprehension*
  • Consent Forms*
  • Double-Blind Method
  • Educational Measurement
  • Human Experimentation
  • Humans
  • Hydrochlorothiazide / adverse effects
  • Hydrochlorothiazide / therapeutic use
  • Hypertension / drug therapy
  • Informed Consent*
  • Male
  • Mental Recall
  • Middle Aged
  • Propranolol / adverse effects
  • Propranolol / therapeutic use
  • Therapeutic Human Experimentation


  • Hydrochlorothiazide
  • Propranolol