1. University of Lübeck; Nursing Research Group, Institute of Social Medicine and Epidemiology; Ratzeburger Allee 160 Lübeck Germany D-23538
2. Fondazione I.R.C.C.S. - Neurological Institute Carlo Besta; Neuroepidemiology Unit; Via Celoria 11 Milan Italy 20133
3. University Medical Center; Institute of Neuroimmunology and Multiple Sclerosis; Martinistr 52 Hamburg Germany 20246
4. Royal Melbourne Hospital, Royal Park Campus; Department of Rehabilitation Medicine; Poplar Road Parkville Melbourne Victoria Australia 3052