Consent is a confounding factor in a prospective observational study of critically ill elderly patients - Flaatten, Hans (Haukeland University Hospital (Bergen, Noruega)) ; Guidet, Bertrand (Sorbonne Université) ; Jung, Christian (University Hospital of Düsseldorf (Alemanya)) ; Boumendil, Ariane (Hôpital Saint-Antoine) ; Leaver, Susannah (Research Lead Critical Care Directorate St George's Hospital) ; Szczeklik, Wojciech (Jagiellonian University Medical College) ; Artigas Raventós, Antoni (Consorci Sanitari Parc Taulí (Sabadell)) ; Andersen, Finn H (Ålesund Hospital) ; Moreno, Rui (Centro Hospitalar Universitário de Lisboa Central) ; Walther, Sten (Linkoping University Hospital) ; Oeyen, Sandra (Universitair Ziekenhuis Gent) ; Schefold, Joerg C. (University of Bern) ; Marsh, Brian (Mater Misericordiae University Hospital (Dublín, Irlanda)) ; Joannidis, Michael (Medical University Innsbruck) ; Elhadi, Muhammed (University of Tripili) ; Nalapko, Yuriy (European Wellness International) ; Fjølner, Jesper (Viborg Regional Hospital) ; De Lange, Dylan W (University Utrecht) ; Universitat Autònoma de Barcelona