1. Clinical & Rehabilitation Sciences Research Group, Faculty of Health Sciences, The University of Sydney, PO Box 170, Lidcombe, NSW 1825, Australia
2. The George Institute for Global Health, PO Box M201, Missenden Rd, NSW 2050, Australia
3. Department of Rehabilitation Sciences, University of Leuven, Tervuursevest 101, B-3001 Heverlee, Belgium