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What is childhood arthritis?

Introduction
Juvenile Idiopathic Arthritis (JIA) is an inflammation of one or more joints, that lasts for more than six weeks, and occurs in children under sixteen. JIA is an umbrella term that covers different forms of arthritis in children, and was formerly known as Juvenile Idiopathic Arthritis. In America, it is still sometimes known as Juvenile Rheumatoid Arthritis, and there is some overlap and confusion about names and classification of subgroups.

In most regions, about one in every thousand children develop some form of ongoing arthritis which is a similar incidence to cerebral palsy or cystic fibrosis. There are infective forms that occur in small populations but which are now very rare in Europe and North America.

What causes arthritis?
We still do not know what causes arthritis in childhood. There would appear to be a number of factors that seem significant, and these are being actively studied. It is extremely rare for brothers or sisters to develop arthritis, but it can happen.
There would appear to be a small inherited factor in spondylo-arthritis and psoriatic groups. There is no research evidence that the weather effects people with arthritis, although many people insist that damp cold weather aggravates their experience of arthritis. It is known that stress, which causes us to become more tense and tired, can influence symptoms and the experience of pain.

Different forms of juvenile arthritis  
In 1999 leading international clinicians agreed to a new classification. This was :

Old Name	New Name
Systemic Juvenile Idiopathic Arthritis (JCA) [rash, spiking fever and joint inflammation]	Systemic onset Juvenile idiopathic arthritis(JIA)
Pauci-articular JCA [four or less joints in first six months]	Oligoarticular JIA
Extended pauci-articular JCA [more than four joints after six months]	Extended oligo-articular JIA
Seronegative polyarticular JCA[as above, with no rheumatoid factor]	Rheumatoid factor negative polyarticular JIA
Juvenile rheumatoid arthritis [more than five joints, with rheumatoid factor]	Rheumatoid factor positive polyarticular JIA
Psoriatic JCA	Psoriatic JIA
Spondyloarthropathy JCA	Enthesitis related JIA

Children with other conditions, (for example Ehlers-Danlos Syndrome, Crohn's Disease) can experience daily consequences of disease that are very similar to children with the above conditions.
In this book, the term juvenile arthritis is used because the majority of experiences are shared by the children and families irrespective of the specific diagnosis.

Who gets arthritis in childhood?
About three quarters of children who get ongoing arthritis are girls, most often developing their symptoms when they are between 2 and 6 years. The table below shows the links between types of arthritis, ages it occurs and the main outcomes of their illness.[1]

MainType (new names)	Age when it starts	Ratio girls to boys	Prognosis
Systemic onset JIA	66% under 5 years	8 girls to every 10 boys	60% good recovery after few years. 20% ongoing cycles of remission and flare-ups. 20% develop ongoing severe arthritis
Oligoarticular JIA	Early childhood Late childhood	7 girls to every 1 boy 1 girl to every 10 boys	20% develop polyarticular JIA
Rheumatoid factor Negative polyarticular JIA	any age	8 girls to every 1 boy	90% recover after few years 10% develop severe JIA
Rheumatoid factor Positive polyarticular JIA	late childhood	6 girls to every 1 boy	less than 50% get severe JIA

It is clear from this information that in most cases it is young girls who develop arthritis and so in this book, the child will often be referred to as a girl. The information and research is equally applicable to boys. There is no research to explore differences between how girls and boys experience arthritis.

The future for your child
Once your child has arthritis, no doctor can tell you exactly how the arthritis will develop. The brief facts above only refer to studies about groups of children. There is no test that could tell you how the disease will affect your child individually nor how long it will last.

However, it is possible to say in the broadest terms that the pattern of disease your child has in the early months (which joints hurt, how many joints or other complications) usually indicates how the disease will show itself in the future. For example, if her knees, neck and hands are mainly affected in the early months, then they will be more likely to become affected each time she has a flare-up in her arthritis.

As shown in the table above, some children who have a few joints affected initially can go on to have arthritis in more joints later. In these cases the disease label should change from oligoarticular to extended oligoarticular JIA.

Summary of key points

1. In the majority of cases, children do recover from arthritis.
2. Getting good medical help early and carrying out the exercise and splinting programmes at home can mean that you prevent some long term problems and enhance the quality of life for her and the rest of the family.
3. Arthritis is unpredictable and symptoms vary from day to day (sometimes from hour to hour). Most children have periods of 'quiet disease' when most symptoms settle down. Some children will have periods almost without any symptoms, but then the disease will flare-up again. You need to continue the medication and exercises when the disease is both active and quiet. It is, therefore, so important to really make the most of the good times, as your child's laughter and achievements during these times will be positive memories and will help you and her cope with the flare-ups.
4. Keeping notes about how the child is feeling and which joints (or rashes, fevers etc) are causing any problem will help you to be accurate about how long the bad times last. When you are in them they feel like months long; actually they are only weeks long.
   Your notes will also help you see any patterns, for example when your child gets stressed (by anything), her elbow and neck may tend to start hurting more. This helps you judge how to reduce the source of stress and treat the consequences of stress promptly.