Objectives: Undifferentiated arthritis (UA) is an inflammatory oligo/polyarthritis where no definite diagnosis can be reached. Patients with UA may progress towards a chronic inflammatory disease, however, in some cases arthritis may completely resolve. To date, a universally accepted diagnostic and therapeutic algorithm for UA is not available.
Methods: We retrospectively studied 192 patients with UA followed by us over the last 10 years in the early arthritis clinic of our institution.
Results: A total of 192 patients, 91 men (47.4%) and 101 women (52.6%), with mean age 57.9±17.8 years, were included in the study. Eighty-four patients (43.7%) presented with acute/subacute mono-/pauci-arthritis, 56 patients (29.2%) with chronic mono-/pauci arthritis, 42 patients (21.9%) with acute polyarthritis and 10 (5.2%) with chronic polyarthritis. From the total of 192 patients, 102 are currently followed. Current diagnosis at the time of this report included: rheumatoid arthritis in 18 (17.6%) patients, self-limiting arthritis in 35 (34.4%), undifferentiated/unclassified arthritis in 45 (44.1%), spondyloarthropathy in 3 (2.9%), and crystal-induced arthritis in one (1%). The time between the initial evaluation and the definitive diagnosis of RA ranged between 6 and 15 months. Seropositivity (RF and/or ACPA) and disease duration were strong predictors of developing RA in our cohort.
Conclusions: Our data indicate that seropositive patients with chronic symptoms carry an increased risk of developing RA, and that these patients may be candidates for a more aggressive treatment.