1 Department of Cardiothoracic Anesthesiology, Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark, frederik.holmgaard@regionh.dk Section of Biostatistics, University of Copenhagen, Copenhagen, Denmark, Center for Statistical Science, Peking University, Beijing, China Department of Cardiothoracic Anesthesiology, Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.