FRI0541 TEN-YEAR OUTCOME OF DIFFERENT SUBTYPES OF UNDIFFERENTIATED INFLAMMATORY ARTHRITIS
Authors: E. Luchikhina, D. Karateev, A. Novikov, G. Lukina, E. Aleksandrova, N. Demidova
Journal: Annals of the Rheumatic Diseases (2020)

Background: A group of patients with recent onset of arthritis always presents a certain difficulty for the practitioner due to its marked heterogeneity. This especially concerns the patients with undifferentiated inflammatory arthritis (UIA). Objectives: To characterize the long-term nosological outcome of clinical and immunological subtypes of early UIA. Methods: A cohort study of patients with recent onset of arthritis with a duration of not more than 12 months (n = 761, 82.8% females, 55.2% RF +) was initiated in 2003. All patients were referred to rheumatologist from GP with suspicion on inflammatory arthritis. Inclusion criteria: age 18 years or more, at least 1 swollen joint at 1 st visit and/or positive squeeze test or morning stiffness for at least 30 minutes. 243 patients were initially classified as having UIA: 46 (18,9%) males, 197 (81,1%) females, age (median, quartiles)- 44 [29;53] years, duration of symptoms- 3 [2;5] months, swollen joints count (66/68)- 2 [1;4], tender joints count 3 [2;6], 85 (35%) rheumatoid factor (RF)+, 63 (25,9%) anti-CCP+. Patients with UIA were followed up for at least 10 years. Results: 28 (11,5%) of patients were lost to follow up. Long-term observation was conducted in 215 patients. 22 (10,2%) of them developed persistent spontaneous (without use of DMARDs) remission. Other patients were finally classified as having: rheumatoid arthritis (RA) 138 (64,2%) and non-RA (25,6%). The spectrum of diagnoses in non-RA group included: ankylosing spondylitis, osteoarthritis, gout, psoriatic arthritis, polymyalgia rheumatica, systemic lupus, mixed connective tissue disease, sarcoidosis, paraneoplastic syndromes. The following characteristics at baseline positively correlated with the development of RA: arthritis of 3 or more joints (p=0,011), arthritis of hand (p=0,005), high ESR (p&lt;0,001), high CRP (p=0,003), PF-positivity (p&lt;0,001), anti-CCP-positivity (p&lt;0,001), older age of onset (p=0,019), higher levels of RF IgM (p=0,027) and anti-CCP (p&lt;0,001). Development of persistent spontaneous remission negatively correlated with polyarthritis (p=0,033), PF-positivity (p=0,034), anti-CCP-positivity (p=0,001). Positive seroconversion was observed: of RF in 10 (4,7%) patients, 8 developed RA, of anti-CCP – in 3 (1,4%) patients, all developed RA. Table. Outcome of different subtypes of patients with UA after 10 years of follow up (n=215). Subtypes of UA Outcome P (Pearson chi-squared test) Non-RA (n=55) RA (n=138) Spontaneous remission (n=22) Mono- and oligo arthritis (n=140) 40 (28,6%) 81 (57,9%) 19 (13,6%) 0,016 Polyarthritis (n=75) 15 (20%) 57 (76%) 3 (4%) RF-negative AND anti-CCP-negative (n=90) 34 (37,8%) 41 (45,6%) 15 (16,7%) &lt;0,001 RF+ OR anti-CCP+ OR low levels (&lt;3 ULN) (n=92) 20 (21,7%) 65 (70,7%) 7 (7,6%) High RF+ AND High anti-CCP+ (n=33) 1 (3%) 32 (97%) 0 Conclusion: Seronegative oligoarticular disease and highly seropositive disease are different subtypes of UIA. Combination of seronegativity and oligoarticular disease (n=52) associated with relatively rare development of RA (36,2%) and high proportion of spontaneous remission (22,4%). Patients who were highly positive (&gt;3 ULN) for both RF and anti-CCP developed RA in 97% of cases and never remitted spontaneously. Disclosure of Interests: Elena Luchikhina Consultant of: Abbvie, Biocad, Sanofi, Celgene, Speakers bureau: Abbvie, Roche, Pfizer, Biocad, MSD, Sanofi, Johnson &amp; Johnson, Glaxo, UCB, Celgene, Novartis, Dmitry Karateev Consultant of: Abbvie, Pfizer, Biocad, Sanofi, Novartis, Lilly, Speakers bureau: Abbvie, Roche, Pfizer, Biocad, MSD, Sanofi, Johnson &amp; Johnson, Glaxo, UCB, Celgene, Novartis, Lilly, Bayer, Alexander Novikov: None declared, Galina Lukina Speakers bureau: Novartis, Pfizer, UCB, Abbvie, Biocad, MSD, Roche, Elena Aleksandrova: None declared, Natalia Demidova: None declared