medwireNews: An analysis of data from three juvenile idiopathic arthritis (JIA) registries shows “relatively similar” rates of comorbidities among JIA patients, say researchers who believe the finding highlights the potential for the registries to be used for synchronized analyses and harmonized collaborations.
“For JIA, the burden of comorbidities is largely unknown,” explain Lianne Kearsley-Fleet (The University of Manchester, UK) and co-investigators in Rheumatology.
They therefore analyzed data from 8066 children and young people (median age at registration 11–14 years) with JIA included in the UK JIA Biologics registries BCRD or BSPAR-ETN, the German Biologic registries BiKeR or JuMBO, and the multinational Pharmachild registry (covering 31 countries), which were initiated in 2010, 2001–2007, and 2011, respectively.
The researchers focused on uveitis, macrophage activation syndrome (MAS), varicella, and history of tuberculosis, finding that at registration, when patients had a median disease duration of 1–3 years, the rates of ever uveitis were similar among patients in the UK, German, and international registries, at 16.0%, 13.0%, and 19.0%, respectively, as were the rates of ever tuberculosis, at 0.6%, 0.0%, and 1.5%, respectively.
On the other hand, a lower prevalence of MAS was observed in the German registries, at 3.9% compared with 24.0% and 14.0% in the UK and international cohorts, respectively.
Varicella rates also differed among cohorts, with only 11% of patients in the German registries ever having had the infection versus a respective 32% and 49% of patients in the UK and international registries.
Kearsley-Fleet et al believe that “varicella vaccination in populations impacted comparability of varicella infections,” with over half (56%) of the German participants being vaccinated compared with 16% of those in the UK registries and 13% of those in the international registry.
The findings were similar at the most recent follow-up, which occurred at a median of 5, 14, and 6 years from JIA diagnosis in the UK, German, and international registries, respectively, with once again similar rates of ever uveitis (19.0, 15.0, and 19.0%, respectively) and ever tuberculosis (0.6, 0.1, and 1.8%) across the cohorts.
And lower rates in the German versus UK and international registries of ever MAS (6.0 vs 15.0 and 17.0%, respectively) and ever varicella (15.0 vs 37.0 and 50.0%).
The study authors also examined the relationships between methotrexate and biologic therapy and the comorbidities. Of note, in the UK and international registries the incidence of uveitis was higher with methotrexate than biologics, at 2.1 versus 0.75 and 0.22 versus 0.14 cases per 100 person–years, respectively, likely because uveitis is most common within the first 2 years of diagnosis when methotrexate is the first-choice therapy, say the researchers.
By contrast, higher rates of uveitis in the German cohort were associated with biologic rather than methotrexate use, “perhaps explained because uveitis occurs most frequently in oligoarthritis patients, and those on [methotrexate] were not enrolled in BiKeR,” say Kearsley-Fleet and colleagues.
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