Affiliation: | 1.Institution of Public Health and Clinical Medicine/Rheumatology, University Hospital, Umeå, 901 85, Sweden;2.Department of Rheumatology, Sunderby Hospital, Luleå, 971 80, Sweden;3.Department of Rheumatology, Sundsvall Hospital, Sundsvall, 851 86, Sweden;4.Department of Rheumatology, Östersund Hospital, Kyrkgatan, Östersund, 831 83, Sweden;5.Institution of Statistics, Umeå University, Umeå, 90187, Sweden |