CLUSTER Post-Doctoral researcher Dr. Stephanie Shoop-Worrall has published an exciting paper in the Lancet Rheumatology. The full paper can be found: https://www.sciencedirect.com/science/article/pii/S2665991320302691
Not all JIA is the same: CLUSTER research identifies 6 ways that JIA changes over time.
Lay summary
What was already known?
Juvenile idiopathic arthritis (JIA) has lots of different symptoms and ways that it can affect the body. This affects how well children and young people feel. We know that a lot of the time, arthritis (joint inflammation or swelling) from JIA gets better and children and young people feel better too. But some young people have said that they still feel bad even though they have no more joint swelling. At the point of being diagnosed with JIA, we don’t know what the experience will be for each person with JIA. If we did know, we would manage individual children and young people in different ways from early on to ensure the best outcome for each of them.
Each person’s experience of JIA will be different, but it may be that groups of children and young people follow the same “pattern” of disease and symptoms over time. We wanted to see if we could identify these groups using new ‘machine learning’ methods. These methods mean that a computer looks for and can find patterns that haven’t been seen before when there is lots of complicated information to sort through.
How was the study carried out?
This study used information from the Childhood Arthritis Prospective Study (CAPS).CAPS follows children and young people from their first hospital visit for up to ten years. Using ‘machine learning’, we looked for groups that might have different patterns of JIA over the first three years following diagnosis in three different ways:
- the number of swollen joints,
- a measure of how active the disease was overall by doctors, and
- a measure of how well the child/young person feels (either reported by the young person themselves or their parents/carers).
There were 1,423 children and young people in this study. Most were female. Most had fewer than five swollen joints when they first came to the hospital. This is called oligoarthritis and is the most common type of JIA. The average age at diagnosis was seven years old.
What was discovered?
We found six groups of children and young people with different patterns of disease over time.
- Low-Remission: This group started with low numbers of swollen joints, lower disease scores, and better wellbeing scores. These improved to remission by one year. Remission is where there is no disease activity.
- Low-Low: This group started with low numbers of swollen joints, lower disease scores and better wellbeing scores. These improved, but not quite to remission, by one year.
- Low-Persistent: This group started with low numbers of swollen joints. Their joints improved but they didn’t feel better within the three years.
- High-Low: This group started with high numbers of swollen joints, higher disease scores and worse wellbeing scores. These improved to remission by one year.
- High-Low-High: This group improved at first but then got worse again after one year.
- High-Persistent: This group started with high numbers of swollen joints, higher disease scores and worse wellbeing scores. Their joints and disease scores improved to three years, but they still didn’t feel much better.
Unfortunately, we were not able to predict which person would fall into which of the six groups. We did see that older children/young adults, and those with enthesitis (which is inflammation around the tendons) were more likely to be in the Low-Persistent or High-Persistent groups. This is where their doctors reported that their joint swelling had improved, but the child or young person didn’t feel completely better. This means we could check in with these people more often to offer extra support.
Why is this important/what is the benefit to children and young people with JIA?
This study shows that JIA improves differently over time in different children and young people. These results should reassure families of children and young people with newly-diagnosed JIA that, with treatment, most will reach low disease activity or remission within the first year after being diagnosed. For some children and young people, their arthritis will “improve” and the doctors will not find any signs of JIA by looking at them but some symptoms, such as pain and fatigue, will still be there. The first step in finding which treatments could help different groups of people is to identify the groups. This study is a major step forward in working out the right treatment at the right time for each unique child and young person with JIA.
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