Childhood arthritis

Arthritis of various forms can start in childhood.

These forms can represent both a childhood onset of the types of arthritis seen in adults such as rheumatoid arthritis or ankylosing spondylitis, or may represent forms only seen in childhood.

These different forms vary in whether they are short lived, resolving (with or without treatment) in a few months or are persistent.

They also vary in the number of joints they involve and whether they have effects outside the joints, of particular concerns are forms that cause inflammation of the eyes.

Data from UK is scarce so estimates are also based on data from the US and Norway.

Thus data on the number of children with arthritis can be considered in a number of ways including:

• The number who newly develop any form of arthritis
• The number of children with an ongoing problem with arthritis

 

The number who newly develop all forms of arthritis

Based on new attendances to specialist paediatric rheumatologists in the UK 10/100,000 children develop inflammatory arthritis¹.

This figure will be an underestimate of the true number as many children, especially with milder forms, who live some distance from where the relatively few paediatric rheumatology services are based, will be missed.

Thus at least 1,000 children under 16 years of age develop inflammatory arthritis in the UK each year.

There are several other musculoskeletal conditions that also affect children that lead to their need to be seen by a specialist paediatric rheumatologist and inflammatory arthritis accounts for between 1 in 3 to 1 in 4 of all such new attendances.

How many children develop arthritis?

	Incidence/100,000	UK estimate
Inflammatory arthritis	10	1,150
All rheumatic disorders	32-42	3,700-4,800

Source¹

Given concerns about these figures underestimating the true figures it is appropriate to use data from other countries with similar (genetically) populations. Recent data from Norway² estimated the total annual incidence of all arthritis was 71/100,000 children.

They also found that the incidence was higher (107/100,000) in those under 8 years than in older children (34/100,000). In many of these children the arthritis was very short lived and occurred in the context of an infection so a more useful figure is the number who went on to have a persisting problem whether or not there was a preceding infection.

How many children develop arthritis?

	Total/100,000	Girls	Boys
All new cases of arthritis	71	5	86
Persisting new cases of arthritis	23	26	22

Source²

Projecting to the UK population would mean over 3,250 girls and 4,800 boys aged less than 16 years develop any form of arthritis each year. Of these around 1,500 girls and 1,200 boys would develop an inflammatory arthritis each year that does not settle spontaneously.

 

The number of children with an ongoing problem of arthritis

Childhood arthritis is rare and there are no detailed surveys available which provide accurate data on the numbers who, at any point in time, have an ongoing problem.

Data to address this comes from hospital specialist clinics on the basis that if there is a continuing problem then the child would attend hospital.

An estimated 294,000 children under age 18 in the US have some form of arthritis or rheumatic condition³.

This represents approximately 1 in every 250 children in the US. If this was applied to the UK population there would be approximately 52,500 under 18 years of age with an on-going problem.

Based on the data above about 1 in 3 to 4, i.e. between 13,000 and 17,500 children have a continuing problem with arthritis.

 

References

1. Symmons DP, Jones M, Osborne J, Sills J, Southwood TR, Woo P. Pediatric rheumatology in the United Kingdom: data from the British Pediatric Rheumatology Group National Diagnostic Register. J Rheumatol 1996; 23(11):1975-80.
2. Riise OR, Handeland KS, Cvancarova M, Wathne KO, Nakstad B, Abrahamsen TG et al. Incidence and characteristics of arthritis in Norwegian children: a population-based study. Pediatrics 2008; 121(2):e299-e306.
3. Sacks JJ, Helmick CG, Luo YH, Ilowite NT, Bowyer S. Prevalence of and annual ambulatory health care visits for pediatric arthritis and other rheumatologic conditions in the United States in 2001-2004. Arthritis Rheum 2007; 57(8):1439-45.