Consent is a confounding factor in a prospective observational study of critically ill elderly patients - Flaatten, Hans; Guidet, Bertrand; Jung, Christian; Boumendil, Ariane; Leaver, Susannah; Szczeklik, Wojciech; Artigas, Antonio; Andersen, Finn; Moreno, Rui; Walther, Sten; Oeyen, Sandra; Schefold, Joerg C.; et al. (2022)