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, 6 = independent), a preserved nutritional status (subjectively assessed by physicians) and without active cancer. Exclusion criteria were an ED stay >24 h, a secondary referral to the ED and refusal to participate. The primary outcome was the mortality at 6 months calculated at the individual patient level. Secondary outcomes were ICU and hospital mortality, as well as ADL scale and quality of life (as assessed by the SF-12 Health Survey) at 6 months. RESULTS: Between January 2012 and April 2015, 3036 patients were included in the trial, 1518 patients in 11 clusters allocated to intervention group and 1518 patients in 13 clusters allocated to standard care. There were 51 protocol violations. CONCLUSIONS: The ICE-CUB 2 trial was deemed feasible and ethically acceptable. The ICE-CUB 2 trial will be the first cluster-randomized trial to assess the benefits of ICU admission for selected elderly patients on long-term mortality. Trial registration Clinical trials.gov identifier: NCT01508819 ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13613-016-0161-5) contains supplementary material, which is available to authorized users.