User testing as a method for evaluating subjects' understanding of informed consent in clinical trials in multiple sclerosis.

The Patient Information Sheet (PIS) is an important aspect of the consent process in a clinical trial that provides potential participants the necessary information for deciding whether to take part in a specific study and for understanding their rights pertaining to participation. User Testing was originally developed to assess how written information about medicinal products performs with its intended users. User testing has been proposed in a small number of clinical trials and has been able to identify subjects' ability or inability to find and understand important information related to providing a valid consent to participate. A 21-item ad hoc user testing questionnaire was applied to 2 PIS used in clinical trials in MS. Sixty subjects were allocated to a group testing an observational study PIS (O-PIS) or to a group testing an intervention study PIS (I-PIS). In the O-PIS group, 19.4% of subjects located all relevant information within the text (21/21) and 3.4% of subjects in the I-PIS group. Overall, 82.1% of subjects testing the O-PIS understood the text and 53.5% of subjects testing the I-PIS understood the text. In the category 'nature and purpose of the trial', one-third of subjects did not understand the text, including the aim of the study. User testing should be considered as a valid tool in evaluating the comprehensibility of PIS in the context of clinical trials MS to assure that subjects provide a valid consent to participate.