Leveraging Machine Learning to Identify Subgroups of Misclassified Patients in the Emergency Department: Multicenter Proof-of-Concept Study - Sage Wyatt; Dagfinn Lunde Markussen; Mounir Haizoune; Anders Strand Vestbø; Yeneabeba Tilahun Sima; Maria Ilene Sandboe; Marcus Landschulze; Hauke Bartsch; Christopher Martin Sauer (Journal of Medical Internet Research)