As many as two-thirds of critically ill patients who consented to take part in a clinical trial do not remember the purpose and risks of the research shortly after. A small study published today in the journal Critical Care, reveals that most Intensive Care Unit (ICU) patients who gave their informed consent to take part in a clinical trial remembered having participated in the trial ten days later. But two-thirds of the patients did not remember the purpose and risks of the trial, although they had been given information about them before the trial started.

Catherine Chenaud and colleagues from the University Hospital of Geneva, Switzerland, studied 44 ICU patients who had been selected for a clinical trial on inflammatory responses. The patients were given a 20-minute presentation about the study, its purpose and its risks and were given a leaflet to read, before agreeing to participate in the trial. They were then interviewed ten days later.

Chenaud et al.' s results show that 35/44 patients remembered having taken part in the trial, but that only 20/44 patients remembered the purpose of the study and only 21/44 patients remembered the study risks. Furthermore, only 14/44 patients remembered both the purpose of the trial and its associated risks. The 14 patients who remembered all aspects of the trial did not differ from other patients, except that they had read the leaflet or had asked at least one question during the presentation, before signing the consent form.

The authors conclude that obtaining informed consent from patients should be a process which is revisited many times, rather than one event at the start of the trial, and that patients should be given information repeatedly during the course of a trial.