1. Department of Haematology; Aarhus University Hospital; Aarhus Denmark
2. Section for Clinical Social Medicine and Rehabilitation, Department of Public Health; Aarhus University; Aarhus Denmark
3. Department of Health Sciences, Community and Occupational Medicine; University Medical Center Groningen, University of Groningen; Groningen The Netherlands
4. Public Health and Quality Improvement; Central Denmark Region; Aarhus Denmark
5. Section for Biostatistics, Department of Public Health; Aarhus University; Aarhus Denmark
6. Department of Rheumatology; Aarhus University Hospital; Aarhus Denmark