Background The clinical courses of monoarthritis are diverse, and predictors of the outcome of monoarthritis remain unknown.
Objectives To evaluate the clinical features and outcomes in patients with monoarthritis and to investigate predictive factors of clinical outcomes.
Methods A retrospective analysis of 171 patients of chronic monoarthritis at a single tertiary hospital between January 2001 and January 2011 was performed. Baseline characteristics, radiographic findings and the clinical course were reviewed.
Results Mean age was 42.8 years and 92 (53.8%) were female. Median follow-up duration was 21 months. Most commonly involved joints were knees (24.0%) followed by wrists (22.8%) and ankles (18.7%). A final diagnosis was established in 74 (43.3%) patients. Of these, 31 (18.1%) patients were diagnosed with rheumatoid arthritis (RA), 23 (13.5%) patients with peripheral spondyloarthritis (SpA), and 19 (11.1%) patients with Behcet`s disease (BD). Among 108 patients who were initially undiagnosed, 85 (78.7%) patients remained undiagnosed monoarthritis with relatively shorter symptom duration and required less treatment. The initially involved joint was a predictive factor for the final diagnosis; the wrist joint for RA (OR 11.58, 95% CI 4.80 to 29.93, p < 0.001), the ankle joint for SpA (OR 6.19, 95% CI 2.38 to 16.08, p < 0.001), and the knee joint for BD (OR 3.43, 95% CI 1.29 to 9.15, p = 0.014). The bony erosion at baseline was associated with progression to oligo- or polyarthritis (OR 2.88, p = 0.030) and with radiographic progression.
Conclusions In patients presenting with monoarthritis, final diagnosis is established in less than half of patients, and majority of undiagnosed patients show benign clinical course. The initially involved joint, presence of erosion at baseline are predictors for the final diagnosis and clinical outcomes.
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Disclosure of Interest None Declared