1. Department of Medicine; Rehabilitation Teaching and Research Unit; Wellington School of Medicine and Health Sciences, University of Otago PO Box 7343 Wellington South Wellington New Zealand
2. Norwegian University of Science and Technology; Department of Community Medicine and General Practice, Faculty of Medicine; Medisinsk Teknisk Forskningssenter Trondheim Norway N-7489
3. Dunedin School of Medicine, University of Otago; Department of Preventive & Social Medicine; PO Box 913 Dunedin New Zealand 9054