Affiliation: | (1) Oslo Sanitetsforenings Rheumatism Hospital, Oslo, Norway;(2) Department of Rheumatology, Betanien Hospital, Skien, Oslo, Norway;(3) Institute of Occupational Health, Central Hospital, Kristiansand, Oslo, Norway;(4) Department of Pharmacology, Institute of Medical Biology, University of Tromsø, Tromsø, Norway |