Key findings for clinicians

The Childhood Arthritis Prospective Study (CAPS) began in 2001 and is a longitudinal inception cohort study funded by Versus Arthritis. CAPS remains one of the largest inception cohorts for childhood arthritis in the world and the data and samples available represent an extremely valuable resource.  We continue to publish a significant number of papers and abstracts and make an important contribution to national and international conferences.  See below tabs for further details.

Genetic studies

Our genetic studies continue to add to the body of evidence suggesting that each subtype of JIA shares similar genetic architecture to a specific adult counterpart.

RF positive polyarticular JIA has often been considered the juvenile equivalent of adult RA due to similar clinical characteristics. One of our recent studies supports this as we have shown that RF positive polyarticular JIA looks genetically more similar to adult Rheumatoid Arthritis (RA) than to other forms of JIA. This adds to a previous study focusing specifically on the HLA region in which we showed that RF positive polyarticular JIA shares similar HLA associations to adult RA. In addition, in this study we reported that the two most common types of JIA (Oligoarthritis and Rheumatoid Factor (RF) negative polyarthritis) are not only genetically similar to each other but also share similar associations to those seen in RF negative adult RA.

These findings have implications for understanding disease mechanisms, novel therapies and shared clinical trials.

The findings from our systemic JIA (sJIA) genetics studies adds to a growing body of evidence that sJIA stands apart from other JIA subtypes, not just in terms of its clinical features but also in its underlying genetic architecture.  This provides important evidence that sJIA should be considered a unique disease with its own specific disease mechanisms and as such should be managed and treated differently. Further increasing our understanding of the genetics of sJIA may help us to understand the pathways involved in this disease and lead to more targeted treatment and potentially identify new therapeutic targets.

We have previously conducted the largest GWAS of MTX response in JIA to date and identified some potential genetic predictors of response. If these can be validated then they may become useful biomarkers to help doctors to identify those children who are unlikely to respond to MTX and therefore should be treated with alternative therapies.

More recently, we have shown that variations in the IL1RN gene can influence response to IL-RA therapy in sJIA patients. This may be useful as we move towards a personalised medicine-based approach to treatment for JIA patients.

Ultimately these genetic studies will enable us to have a greater understanding of the causes of this condition. Our results support the idea that genetic profiling might enhance our ability to classify and understand disease mechanism within the different forms of JIA which in turn may lead to more targeted therapeutic approaches and development of novel therapies.

Clinical studies

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. However, there is no single test for clinically inactive disease and lots of different criteria could be used to determine whether the disease has reached this state. We found 13 different definitions of clinically inactive disease across 17 studies from around the world. This is only important if they don’t agree with each other about which child or young person has reached clinically inactive disease.

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 should not expect to have no signs or symptoms of disease after one year of hospital treatment.

The differences between the definitions of clinically inactive disease included whether a blood test for ESR was included or not and whether patient/parent input was used or not. We found that a blood test for ESR may not be useful when looking for clinically inactive disease, although blood tests can still be useful for other reasons, such as monitoring for treatment side effects. However, we found that different children and young people were identified as having reached clinically inactive disease depending on whether patient/parent input was used or not. Around 2 in 5 young people reached clinically inactive disease when both doctor and patient/parent input was used. Fewer, around 1 in 4, reached clinically inactive disease when only doctor input was used.

In the next study, we looked at what happened to these children and young people in the long-term. Five years after coming to hospital, joint movement was better for those who had few signs and symptoms of disease and even better for everyone that had reached any definition of clinically inactive disease at one year. However, those who had clinically inactive disease using both doctor and patient/parent input did the best in terms of their quality of life and their ability to do everyday tasks. This means that information from both doctors and patient/parents is important for understanding and treating JIA.

Pain studies

We have continued our work on pain in JIA and have shown that even when disease activity is controlled a proportion of children continue to have high levels of pain. Identification of children at risk of continued high levels of pain might help target them for early psychological and physio-based support to manage their pain. We have developed a pain perception questionnaire which 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 are continuing to develop our app to measure pain (My Pain Tracker) and the associated visualisations that will be necessary to transfer this to clinical use.

We have undertaken some qualitative work which has shown that the assessment of pain by health care professionals (HCPs) in patients with JIA may be limited by knowledge, skills and attitudinal factors. HCPs’ beliefs about pain in JIA alongside limited time in clinic often mean that pain is a low priority for them. However, pain is often a high priority for patients and therefore there is a need to change opinions on pain management by professionals managing children and young people with JIA.

Other studies

We have highlighted some of the challenges involved when studying a condition that starts in childhood such as JIA. Many of the questionnaires used are initially completed by parents but after the age of 11 are completed by the young person themselves. In CAPS, adolescents aged 11 to 17 years self-completed the A-CHAQ and HAQ (two versions of a questionnaire that measures function) and parents simultaneously completed the P-CHAQ (parent version of same questionnaire) at baseline and one year. We found that whilst there is relatively high agreement, data from the two groupings are not completely interchangeable. This could have an impact on studies looking at function over the lifespan of the disease.