1. Department of Clinical EpidemiologyAarhus University HospitalAarhusDenmark
2. Center for Clinical Health Services ResearchDepartment of Clinical MedicineAalborg UniversityAalborgDenmark
3. Centre for Statistics in MedicineNuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Sciences (NDORMS)University of OxfordOxfordUK