Considerations for co-enrolment in randomised controlled effectiveness trials in critical care: the SPICE-8 co-enrolment guidelines.

The Australian and New Zealand Intensive Care Society Clinical Trials Group and other investigator-led trials groups in critical care publish policies and guidelines outlining the rationale for considering co-enrolment in large, randomised controlled trials in intensive care medicine. However, none present a checklist of criteria by which a request for permission to co-enrol in an existing trial can be assessed. Consequently, such requests tend to be made and assessed on an ad hoc basis. Based on our experience in the SPICE III randomised controlled trial, we propose eight broadly applicable criteria (the SPICE-8 criteria) to be satisfied before co-enrolment should be approved. Reporting co-enrolment in trials, for regulatory purposes and in publications, is uncommon, partly because of the complexity involved in explaining a lack of a plausible coenrolment effect. We suggest that noting compliance with these criteria would simplify such reporting and enhance transparency.