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. Clusters were healthcare centres with at least one emergency department (ED) and one ICU. Healthcare centres were randomly assigned either to recommend a systematic ICU admission (intervention group) or to follow standard practices regarding ICU admission (control group). Clusters were stratified by the number of ED annual visits (<44,616 or >44,616 visits), the presence or absence of a geriatric ward and the geographical area (Paris area vs other regions in France). All elderly patients (>= 75 years of age) who got to the ED were assessed for eligibility. Patients were included if they had one of the pre-established critical conditions, a preserved functional status as assessed by an ADL scale >= 4 (0 = very dependent