Background Recent-onset inflammatory arthritis (IA) may represent a broad range of diseases. Few studies have examined the full spectrum of diagnostic outcomes in an unselected cohort of recent-onset IA patients.
Objectives To describe the disease spectrum and 2-year outcome of recent onset IA in a large multicenter study in Norway.
Methods Data from the Norwegian Very Early Arthritis Clinic (NOR-VEAC), a 2-year longitudinal observational study of 1118 patients (age 18–75 yrs) with inflammatory arthritis of ≤16 weeks duration, were used. Exclusion criteria were arthritis due to crystal deposits, trauma, osteoarthritis and septic arthritis. Herein we included all patients with follow-up information. Descriptive methods were applied to describe the whole range of diagnostic outcomes (clinical diagnoses made by the treating rheumatologist), as well as disease persistency (defined as disease modifying anti-rheumatic drug (DMARD) use and/or persistent joint swelling) vs resolution of disease for each clinical diagnosis. Patients with temporary DMARD use were classified as no-DMARD users if they were observed for ≥1 year after DMARD cessation. If a patient dropped out of the study before 2 years, the last outcome information was used in a last observation carried forward approach.
Results 1077 patients (96.3%) were included in the current analyses, of these 64.9% had 2-year follow-up data. Duration of joint swelling before inclusion [median (25–75 perc.)] was 34 (13–66) days, mean (SD) age 46.1 (14.8) years, 54.7% were females, 16.9% anti-CCP positive, and 21.9% anti-CCP and/or RF positive. Presentation as mono-, oligo- (2–4 swollen joints), and polyarthritis (≥5 swollen joints) had approximately the same frequency, 32.5, 35.7 and 31.8%, respectively.
After 2 years 33.0% used DMARDs, and a further 9.3% had joint swelling without DMARD use. The arthritis resolved in the remaining 57.6%. The final clinical diagnoses and their respective outcomes are shown in Figure 1. The most common final diagnoses were undifferentiated arthritis (UA) (39.9%), rheumatoid arthritis (RA) (22.7%), reactive arthritis (17.1%), psoriatic arthritis (6.0%) and sarcoid arthropathy/Löfgren's syndrome (6.2%). A final diagnosis of sarcoid arthropathy, reactive arthritis and UA carried the best prognoses, with resolution of arthritis without DMARDs in 91.0, 85.9 and 73.7%, respectively. Patients presenting with polyarthritis developed persistent disease more often than patients with oligo- or monoarthritis (67.6%, 34.9 and 26.0%, respectively) (p<0.001).
Conclusions Among 1077 patients with IA of ≤16 weeks duration, UA was the most common diagnosis after 2 years, 22.7% were diagnosed with RA and 6.0% with psoriatic arthritis. The arthritis resolved without DMARDs in the majority of the patients. This is, as far as we know, the first study to describe the whole range of diagnostic outcomes in an unselected cohort of recent-onset arthritis, as well as the persistency of disease according to each diagnosis.
Disclosure of Interest E. S. Norli: None declared, G. Hetland Brinkmann: None declared, T. K. Kvien Consultant for: Tore K Kvien has received fees for speaking and/or consulting from AbbVie, Biogen, BMS, Boehringer Ingelheim, Celltrion, Eli Lilly, Epirus, Janssen, Merck-Serono, MSD, Mundipharma, Novartis, Oktal, Orion Pharma, Hospira/Pfizer, Roche, Sandoz and UCB, O. Bjørneboe: None declared, A. Julsrud Haugen: None declared, H. Nygaard: None declared, C. Thunem: None declared, E. Lie: None declared, M. Mjaavatten: None declared