1. University Medical Center Groningen, University of Groningen; Department of Health Sciences, Community and Occupational Medicine; A. Deusinglaan 1 Groningen Netherlands 9713 AV
2. Academic Medical Center; People and Work Outpatient Clinic; Amsterdam Netherlands
3. PsychoVitaal; Amstelveen Netherlands
4. Academic Medical Centre, University of Amsterdam; Coronel Institute of Occupational Health; PO Box 22700 Amsterdam Netherlands 1100 DE
5. Guy's and St Thomas NHS Foundation Trust; London UK
6. Deutsche Krankenhausgesellschaft (German Hospital Society); Berlin Germany
7. Finnish Institute of Occupational Health; Cochrane Occupational Safety and Health Review Group; PO Box 310 Kuopio Finland 70101