THU0674 CLINICAL PRESENTATION AND MANAGEMENT OF MONO- AND BILATERAL KNEE ARTHRITIS: RESULTS FROM THE LEIDEN EARLY ARTHRITIS CLINIC COHORT
Authors: Johanna M. Maassen, Xanthe Matthijssen, Sytske Anne Bergstra, Cornelia Allaart
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Patients presenting with arthritis in one or both knees propose a challenge regarding diagnosis, prognosis and treatment decisions. <h3>Objectives</h3> To characterize the patients with knee arthritis who presented to the Leiden Early Arthritis Clinic (EAC) and to evaluate the disease course and initial treatment decisions. <h3>Methods</h3> All patients with arthritis confined to the knee(s) were selected from all patients included in the EAC between 1993 and 2015. The EAC captures patients with arthritis and symptom duration &lt; 2 years, excluding arthritis diagnosed at presentation as definite infectious, gouty or osteoarthritic. EAC follow up is at 2 weeks, 3 months and thereafter yearly. Medical files were revised for information on treatment and clinical outcomes. Baseline characteristics were summarized, treatment and outcome was evaluated over time up to 12 months. Patients were stratified over 3 groups: 1. Early remission (at 3 months no clinical synovitis and no flare in the first year); 2. Persistent gonarthritis at 3 months (improving or stable up to 12 months, without progression); 3. Progression to oligo-/polyarthritis ≤ 12 months. Between-group differences were analysed using χ<sup>2</sup>, Fischer exact tests, two-way ANOVA or Kruskal Wallis tests. <h3>Results</h3> Of the 206 patients identified, 174 (85%) had mono- and 32 (15%) bilateral gonarthritis. Early remission was observed in 67/206 patients (32.5%, group 1), gonarthritis persisted in 109/206 patients (52.9%, group 2) and progression to oligo-/polyarthritis occurred in 30/206 patients (14.6%, group 3) within the first 12 months. At 12 months, 32/109 (29.4%) patients in group 2 still had gonarthritis, 40/109 (36.7%) were in remission, and 37/109 (33.9%) patients had been lost to follow-up (11 patients were in remission and 26 patients still had (residual) gonarthritis at the last available visit). RF and ACPA positivity and high ESR at baseline were predictive for progression (group 3), but did not differ between patients in groups 1 and 2. There was a trend for longer symptom duration at presentation in group 3 (76.5 days, IQR 25.5-175.5, p=0.040 vs. group 1) (table 1). The initial treatment consisted of NSAIDs (in 125/206 patients, 60.7%), an intra-articular corticosteroid injection (IAC) (39/206, 18.9%) or other (29/206, 14.1%) including prednisone, csDMARDs, anti-gout medication and antibiotics (AB). In 13/206 (6.3%) patients symptoms remitted without any treatment. No differences in initial treatment were observed between groups 1, 2 and 3. During the first year, in 62/206 patients (30.1%) treatment remained limited to NSAIDs, most often in group 1 (p &lt;0.01). IACs were (also) administered to 93/206 (45.1%), mainly in group 2 and 3 (p &lt;0.01). Three patients (1.5%) underwent Yttrium radiosynovectomy, all in group 2. CsDMARDs were (also) prescribed in 28/206 patients (13.6%) and 2/206 patients (&lt;1%) subsequently received a bDMARD. Prednisone was prescribed in 11/206 patients (5.4%). DMARD therapy was prescribed most frequently in group 3 (p&lt;0.01) as was prednisone (p=0.20). ABs were prescribed in 23/206 patients (11.2%), when a diagnosis of Borreliosis or other bacterial arthritis was made or suspected, and 6/206 patients (3.0%) received with colchicine and/or allopurinol (NS between the groups) (table 2). <h3>Conclusion</h3> Of 206 consecutive patients with undifferentiated arthritis limited to the knee(s) the majority was in remission after 12 months. Progression to arthritis in other joints was relatively rare. Routinely acquired baseline characteristics could not completely predict the disease course at presentation and initial treatment choices suggest that physicians could not either. To timely start appropriate treatment, apart from effective treatment options, more research is needed to identify disease characteristics that predict chronicity or progression and identify patients that could profit from early more effective therapy. <h3>Disclosure of Interests</h3> Johanna M. Maassen: None declared, Xanthe Matthijssen: None declared, Sytske Anne Bergstra Grant/research support from: Bristol-Myers Squibb provided funding for the completion of this study and the development of the abstract., Cornelia Allaart: None declared