Oligoarticular PsA occurs in 47% of patients, presents similarly to polyarticular disease
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Oligoarticular disease occurs in 47% of patients with psoriatic arthritis and presents similarly to polyarticular disease, often affecting small joints of the hands and feet, according to data published in The Journal of Rheumatology.
The researchers additionally noted that, among patients with oligoarthritis, 39% will progress to polyarticular disease.
“In Moll and Wright’s original description of psoriatic arthritis (PsA), the authors identified oligoarticular disease, defined as ≤ 4 joints, as the most frequent pattern observed,” Dafna D. Gladman, MD, FRCPC, of the University of Toronto and Toronto Western Hospital, in Canada, and colleagues wrote. “However, the prevalence of oligoarticular disease has varied in subsequently reported series. Moreover, it has been demonstrated that the patterns do not necessarily remain stable over time.”
“In the past 2 decades, many new medications have been approved for the treatment of PsA,” they added. “Many of the randomized controlled trials required 5 tender and swollen joints, whereas others required only three tender and swollen joints and had an average of 20 tender and 15 swollen joints; in some jurisdictions, patients with oligoarticular disease (< 5 joints) are not able to receive biologic therapy. It remains unclear whether patients with oligoarticular disease differ from those with polyarticular disease and what characteristics predict progression from oligoarticular to polyarticular disease.”
To examine whether the presentations of oligoarticular and polyarticular disease differ, and to identify the potential predictors for progression from the former to the latter in PsA, Gladman and colleagues studied patient data from the University of Toronto. The analysis included patients who entered the PsA clinic between 1978 and 2018, within 12 months of diagnosis, and had at least two visits.
In all, 407 patients were identified and followed at 6- to 12-month intervals based on standard protocol, which included collecting demographic, clinical history and laboratory information, as well as detailed clinical examinations and patient questionnaires. Patients underwent radiographs at 2-year intervals. The researchers defined oligoarthritis as the presence of four or fewer inflamed joints, and progression as an increase to five or more joints. The statistical analyses included logistic and Weibull regression models, adjusted for age, disease duration and sex.
According to the researchers, 47% of the included patients presented with oligoarthritis. Although demographic features were similar between those with polyarthritis and oligoarthritis, more patients with polyarthritis presented with dactylitis and enthesitis. There was similar joint distribution between the two groups, with the most impacted areas being the small joints of the hands and feet. Patients with polyarthritis demonstrated higher Health Assessment Questionnaire and lower 36-item Short Form Health Survey (SF-36) scores.
Among the 192 patients with oligoarticular disease, 61% remained oligoarticular awhile 39% progressed to polyarthritis. A lower SF-36 mental component summary score predicted progression to polyarthritis.
“This study highlights the prevalence of oligoarthritis and the fact that a proportion of patients presenting with oligoarthritis progress to polyarthritis,” Gladman told Healio Rheumatology. “Moreover, it showed that the oligoarthritis is similar to that of polyarthritis. It also demonstrated that the most commonly affected joints are the small joints of the hands and feet, not just large joints. Therefore, it is important to assess all joints in patients with psoriatic arthritis, and oligoarthritis should be treated aggressively.”
Perspective
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Psoriatic arthritis is a challenge to diagnose, and the systems affected by PsA are many. Research that is being done to attempt to classify the patient’s disease is proving to be just as challenging. We think we know what PsA looks like and what patterns the disease will take, but as we learn more and more about PsA those patterns change over time. Thinking in terms of peripheral, axial or both and evaluating the domains involved may enable us to determine the most appropriate treatment for our patients.
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