1. Academic Medical Center, University of Amsterdam; Coronel Institute of Occupational Health and Research Center for Insurance Medicine; PO Box 22700 Amsterdam Netherlands 1100 DE
2. University of British Columbia; Division of Rheumatology; Vancouver BC Canada
3. Monash University; Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine; Alfred Hospital, Commercial Rd Melbourne Victoria Australia
4. University of Helsinki; Department of Public Health; PO Box 41 Helsinki Helsingin yliopisto Finland 00014
5. Academic Medical Centre; Coronel Institute of Occupational Health; Meibergdreef 9 Amsterdam Netherlands 1105 AZ