Among the seven subtypes of juvenile idiopathic arthritis (JIA), oligoarticular JIA (oJIA) and psoriatic JIA (psJIA) display a predilection for onset in early childhood. We examined whether meaningful differences in clinical phenotype justify the distinction between these conditions.
We performed a chart review to identify children with psoriatic and non-psoriatic oligoarticular-onset JIA. Clinical and demographic features of the two groups of children were compared.
Of the 390 children included in the study, 303 met the criteria for oJIA and 87 met the criteria for oligoarticular-onset psJIA. Both groups had a peak age of onset at 2-3 years, though psJIA had appreciable incidence into adolescence. Onset before 5 years of age was observed in 215 (71%) and 38 (44%) children respectively (p<0.001). Within this age category, children with psJIA demonstrated similar gender ratio and anti-nuclear antibody status to those with oJIA but exhibited a distinctive clinical pattern, with a tendency to involve the wrists and small joints of the hands and feet. Conversely, among all children presenting with oligoarthritis in early childhood, those with wrist or small joint involvement were more likely to have nail pits, psoriasis, or a family history of psoriasis than those without (p<0.05), supporting the association of this joint pattern with the psoriatic diathesis.
Even taking into account age of onset and number of joints, oJIA and psJIA remain clinically distinct, though important demographic overlap remains. These findings support separate diagnostic categories but justify further investigation into the similarities as well as differences among these children.