Boter and colleagues have proposed a compromise to obtaining fully informed consent before enrolment for randomised trials that have primary outcomes based on a subjective measure, which makes blinding impossible and bias likely. This compromise aims to involve the patient and show them as much respect as possible. As with all compromises it is imperfect. From the trialists' point of view it still has several drawbacks compared with obtaining consent only for follow up.

Telling patients that there is a secret additional research question is likely to reduce the proportion of patients who agree to participate …