Clinical research intervention studies of comprehension of informed consent in non-psychiatric adult populations were eligible for inclusion.
The studies included patients in oncology/chemotherapy/cancer trials, perinatal trials, influenza or HIV vaccine trials, patients with acute myocardial infarction, diabetes, asthma, chronic conditions, anaesthesia patients and healthy volunteers. Studies compared standard informed consent with simplified written consent documents, multimedia approaches (such as educational video) and the use of a consent educator. The tools used to define and measure comprehension varied widely. Measurement tools included semi-structured or open-ended interviews, questionnaires, focus group transcripts, self-report and surveys.
The authors stated neither how the papers were selected for the review nor how many reviewers performed the selection.