Two-thirds of children diagnosed with juvenile idiopathic arthritis are classified later as having a different form of arthritis as adults, with 72% of them requiring disease-modifying medication and 13% forced into retirement, according to a cross-sectional analysis of a registry database.

But among patients with inactive disease, more than one-third are off medication, and the majority have either no or very mild disabilities, reported Filipa Oliveira-Ramos, MD, of Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, Lisbon, and her colleagues ( RMD Open 2016;2:e000304. doi: 10.1136/rmdopen-2016-000304 ).

“This study shows that JIA [juvenile idiopathic arthritis] represents a group of very different diseases that evolve differently in adulthood,” the investigators wrote. “We found that most patients with JIA who are followed in adult rheumatology clinics fulfilled classification criteria for adult rheumatic diseases, [and] maintain active disease and functional impairment at long-term follow-up.”

The team used data from the Rheumatic Diseases Portuguese Register database to discern how rheumatic disease classifications evolve as people with JIA grow into adulthood. The analysis comprised 426 patients and examined fulfillment of adult classification criteria, function as assessed by the Health Assessment Questionnaire (HAQ), clinical disease characteristics as assessed by the Juvenile Arthritis Damage Index–articular (JADI-A) and Juvenile Arthritis Damage Index–extra-articular (JADI-E), and disease activity.

The patients were a mean of 34 years old at the time of the last visit entered into the database. The patients’ mean disease duration was 22.5 years, including 80% with at least 10 years and 24% with more than 30 years.

All had been diagnosed with JIA, at a mean age of about 10 years. Disease categories were persistent oligoarthritis (19%), extended oligoarthritis (14%), rheumatoid factor–positive polyarthritis (17%), rheumatoid factor–negative polyarthritis (18%), systemic disease (10%), enthesitis-related arthritis (19%), psoriatic arthritis (3%), and undifferentiated arthritis (1%).

A total of 72% of patients were still employed, although 13% had retired because of disease-related disability. Most (67%) still had active disease, and 72% were taking a disease-modifying antirheumatic drug.

JIA had evolved into numerous new diagnoses, the team observed. Most patients with systemic-onset JIA (92%) were classified as having adult Still’s disease – more than half (58%) with persistent systemic features and about 42% with predominately polyarticular involvement.

The majority of patients with RF-positive polyarthritis (96%) and of those with RF-negative polyarthritis as children (57%) fulfilled the adult criteria for rheumatoid arthritis.

Patients who had persistent oligoarthritis as children were, as adults, most likely be classified with spondyloarthritis (35%), although 59% remained unclassifiable.

Most of the patients with extended oligoarthritis as children were later classified as having either rheumatoid arthritis (39%) or spondyloarthritis (26%). Most patients with juvenile enthesitis-related arthritis were also reclassified as having spondyloarthritis (95%).

All of those with childhood psoriatic arthritis retained that classification as adults.

A smaller portion of patients (21%) were unclassified as adults, the investigators said. Most of these patients had RF-negative polyarticular or oligoarticular classifications as children.

In a series of multivariate analyses, the team found a number of significant associations with adult outcomes. After adjustment for International League of Associations for Rheumatology (ILAR) category, inactive adult disease was associated with shorter disease duration, less delay in diagnosis, a lower HAQ score, and less exposure to corticosteroids. A higher HAQ score was associated with a longer disease duration and exposure to biologics, while a lower HAQ was associated with the persistence of systemic disease features.

Higher JADI-A scores were associated with disability-related retirement, longer disease duration, and past or current use of biologics.

Another series of multivariate models assessed outcomes associated with inactive disease. Patients who were older at disease onset were more likely to have inactive disease as adults. A positive test for anticitrullinated protein antibodies decreased the likelihood of disease inactivity by 93%.

Finally, the investigators evaluated associations with function and clinical characteristics. Younger age at disease onset was associated with higher HAQ and JADI scores in adulthood. Patients with RF-positive polyarthritis and systemic-onset JIA were more likely to have worse JADI-A and JADI-E scores, compared with patients who had persistent oligoarthritis. Corticosteroid exposure was also predictive of worse extra-articular scores on the JADI.

“Understanding the way these juvenile diseases progress could add useful information for the ongoing discussion of a new classification capable of better unifying the language between pediatric and adult care,” the authors concluded.

None of the authors had financial disclosures.

On Twitter @alz_gal


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