Despite the increasing number of treatments, children with juvenile idiopathic arthritis (JIA) still experience disease activity most of the time, real-world data from Sweden suggest.
The findings highlight the need to find new treatments for this young patient population, the scientists said.
The study, “Outcome in juvenile idiopathic arthritis: a population-based study from Sweden,” was published in the journal Arthritis Research & Therapy.
JIA is the most common rheumatic disease in children. It is often characterized by persistence (at least six weeks) of joint inflammation before age 16, and can induce joint dysfunction if left untreated.
Long-term outcomes of JIA patients have improved in the last three decades, thanks to the availability of better therapies and improved diagnostic approaches.
Researchers from Sweden’s Lund University evaluated the long-term course of JIA in 251 children younger than 16 from Skåne, the southernmost county of Sweden. Participants were diagnosed between 2002 and 2010.
Almost half of the children (44.7%) had oligoarthritis, while 20.7% had polyarticular JIA, 16.3% had undifferentiated JIA, 8.8% had enthesitis-related arthritis (ERA), 6.8% juvenile psoriatic arthritis, and 2.8% had systemic JIA.
The mean annual incidence rate of JIA was 12.8 per 100,000 children under 16 years, being more prevalent among females than males (17.5 versus 8.3 cases per 100,000 per year).
Most affected girls were diagnosed by age 2. The peak of JIA incidence in boys was at age 12. The median time between symptom onset and diagnosis was five months. This was longest in children with juvenile psoriatic arthritis, as diagnosis took as long as 14 months.
Over a median of eight years, almost all patients (98%) took non-steroid anti-inflammatory drugs (NSAIDs) at some point, most commonly methotrexate (60.6%). Local, intra-articular steroid injections were also common (78.9%). Tumor necrosis factor (TNF)-alpha inhibitors were used either alone by 23.9% of the children or in combination (83.3%).
Yet, while 40% of the follow-up years were with inactive disease — defined as no signs of arthritis or uveitis (inflammation of the eye) — 54.8% of the time they had active JIA due to arthritis with or without uveitis and 5.2% were active because of uveitis only.
Those with sJIA had the highest percentage of years with inactive disease (64%), followed by children with persistent oligoarthritis (46.5%) and undifferentiated JIA (43.5%).
Thirty children (10.8%) had uveitis. Ten had acute uveitis, 20 chronic uveitis, and three children had both.
Clinical records also showed that 23 children (9.2%) underwent corrective orthopedic surgery of the joints, eight of whom had multiple procedures. Still, only 11 children (4.4%) had undergone large orthopedic surgery, such as joint regeneration or alignment.
The need for orthopedic surgery was more common among patients with rheumatoid factor (RF)-positive polyarticular JIA (23.5%). RF is an antibody whose levels are generally higher in people with rheumatoid arthritis.
Overall, “[t]he need for orthopedic surgery and the presence of uveitis are diminished compared to studies with patients diagnosed more than 20 years ago,” the researchers stated.
“Children with JIA, however, still experience disease activity more than 50% of the time,” they added. “In conclusion, we still have long-term challenges in the care for children with JIA, in spite of state-of-the-art treatment.”