Johannesdottir, K.B., Kehlet, H., Petersen, P.B., Aasvang, E.K., Sørensen, H.B.D., Jørgensen, C.C. and Centre for Fast-track Hip and Knee Replacement Collaborative Group, O. behalf of 2021. Machine learning classifiers do not improve prediction of hospitalization > 2 days after fast-track hip and knee arthroplasty compared with a classical statistical risk model. Acta Orthopaedica. 92, (Nov. 2021). DOI:https://doi.org/10.2340/17453674.2021.843.