Key findings

Key findings

The Childhood Arthritis Prospective Study (CAPS) began in 2001 and is funded by Versus Arthritis. CAPS is one of the largest studies of its type for childhood arthritis in the world and the data and samples available are an extremely valuable resource. We have published a significant number of research papers and make an important contribution to national and international conferences. See below tabs for further details.


One of the most important parts of CAPS is looking at genes and how they affect JIA. We have had various scientific research papers published to help advance this subject and we are contributing to large international collaborative studies. For example, systemic JIA is one of the rarer types of JIA and can be more severe than the others. Current treatments of this disease often involve drugs used in other types of JIA. However, we have found that systemic JIA is genetically very different to the other types of JIA and should be considered a unique condition. This should hopefully lead to new, more effective treatments for this severe form of JIA.

Another type of JIA is known to be similar to adult rheumatoid arthritis (RA). This type, called Rheumatoid Factor (RF) positive polyarticular JIA, is rare and so far only small genetic studies have been performed on it. Our research has shown that RF-positive polyarticular JIA looks genetically more similar to RA than it does to other forms of JIA. This genetic similarity may give us a greater understanding of the causes of this disease. It could also mean that potentially useful treatments developed for use in adult RA could be used for this type of JIA, as well as the development of new treatments.

There are a number of different types of JIA. A system created by the International League of Associations for Rheumatology (ILAR) has been developed to help us describe these different types of conditions that make up JIA. This system is based on clinical data but we felt that including genetic data too could improve it. We have found that, as well as RF-positive polyarticular JIA being genetically similar to RA, the two most common types of JIA (Oligoarthritis and Rheumatoid Factor (RF) negative polyarthritis) are also genetically similar to each other. This may help improve the way these diseases are classified and help us to better understand how these diseases are caused, as well as develop new treatments.


The aim for children and young people with JIA is to get better, where ideally there are no symptoms from their arthritis. This is what researchers refer to as “clinically inactive disease”. Doctors may keep changing treatments until clinically inactive disease has been reached.

Using CAPS data, we found that fewer than half of children and young people with JIA have clinically inactive disease after one year of hospital care. This means that most children and young people are likely to have signs or symptoms of disease after one year of hospital treatment.

However, there is no single test for clinically inactive disease and this could be determined in lots of different ways. We found 13 different definitions of clinically inactive disease across 17 studies from around the world. The differences between the definitions included whether a blood test was included or not and whether information from patients or parents was used or not.

One of our researchers found that children whose disease was clinically inactive according to both doctors and themselves/parents did the best over the first five years after coming to hospital with JIA. We compared their results with a group whose disease was clinically inactive according to doctors only.

Both groups did equally well in their joint movements, but the first group had better quality of life and everyday function. We found that information from both doctors and patients/parents should be used to better treat joint and non-joint symptoms in young people with JIA.


Our work on pain in JIA has shown that even when disease activity is controlled, some children continue to have high levels of pain. Identifying children at risk of continued high levels of pain could lead to early psychological and physio-based support to manage their pain.

My Pain Tracker (MPT) is an app that the research team have developed for children and young people with pain. The app ‘tracks’ pain as children use symbols, faces, words and colour within the app to describe pain on their body. The app also asks questions about what the pain might have stopped you from doing during the day.

We found that children liked using our app because they could track how their pain made them feel, how they could use different symbols to describe their pain and that they could use new technology like iPads to make tracking pain fun. The children thought that MPT made talking about pain with doctors and parents much easier and said it was ‘cool’ and ‘interesting’ to use.

We developed a pain perception questionnaire (PPQ-YP) which you may have received from us. The PPQ-YP may help in understanding young people’s beliefs about the causes and consequences of their pain, again ultimately helping better self-management of pain.


We have studied the height of children with JIA to see what might cause poor growth in these children. We looked at data from 568 patients over a 3 year period and found that patients were average height for their age and gender when they were diagnosed.

However, after 3 years, some patients were shorter than they should have been for their age and gender, with 39% having restricted growth. Despite this, patients with the lowest initial height scores were also the most likely to see an improvement after 3 years. The impact of JIA on growth is important to children and families and this study provides useful data to support clinical care.