1 Department of General Practice, Amsterdam UMC, location Vrije Universiteit, de Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands. [email protected].
2 Amsterdam Public Health Research Institute, Amsterdam, The Netherlands. [email protected].
3 Department of Orthopaedic Surgery, Copenhagen University Hospital Hvidovre, Copenhagen, Denmark.
4 Department of Physiotherapy, Singapore General Hospital, Singapore, Singapore.
5 Duke-NUS Graduate Medical School, Medicine Academic Programme, Singapore, Singapore.