Designing and conducting a cluster-randomized trial of ICU admission for the elderly patients: the ICE-CUB 2 study.

Background: The benefit of ICU admission for elderly patients remains controversial. This report highlights the methodology, the feasibility of and the ethical and logistical constraints in designing and conducting a cluster-randomized trial of intensive care unit (ICU) admission for critically ill elderly patients.

Methods: We designed an interventional open-label cluster-randomized controlled trial in 24 centres in France.