Juvenile idiopathic arthritis (JIA) is an umbrella term used to define a group of conditions occurring among children that include some form of chronic arthritis. JIA is one of the more common chronic diseases of childhood.
Criteria for JIA include onset before age 16, persistent, objective arthritis in 1 or more joints for at least 6 weeks, and exclusion of other potential causes of childhood arthritis1.
JIA is classified into 7 mutually exclusive categories: systemic, polyarthritis rheumatoid factor positive, polyarthritis rheumatoid factor negative, oligoarthritis (persistent and extended), psoriatic arthritis, enthesitis-related arthritis, and undifferentiated arthritis. Oligoarthritis (persistent and extended) and polyarthritis rheumatoid factor negative are the most prevalent of the seven types.
Because of various forms of juvenile arthritis and conflicting case definitions there are varying estimates of the number of cases of JIA. The most commonly cited number is 70,000 -100,000 cases (active and inactive) among children under age 16.1
A 2007 CDC study estimates that 294,000 US children younger than age 18 (or 1 of 250 children) have been diagnosed with arthritis or another rheumatologic condition.3 These estimates include
16,000 classified as rheumatoid arthritis and other inflammatory polyarthropathies.
There are no national studies of the incidence of juvenile arthritis.
Rates from geographically limited, short-term studies done in the United States between 1975 and 1996 yield incidence rate estimates ranging from 6.6–15 per 100,000 children, which translates into 4,800 to 11,000 new cases of childhood (younger than age 18) arthritis in the United States in 2003 and 4,300 to 9,700 in children younger than age 16.1
Overall, juvenile arthritis occurs more frequently in girls than boys. Family studies also suggest an increased risk for certain genetic make-ups.
Incidence rates vary by place. Even in one area, rates vary over time. These facts suggest an environmental component to the occurrence of juvenile arthritis.
Using codes for Arthritis and Other Rheumatic Conditions (AORC) as defined in adults, the Centers for Disease Control and Prevention’s (CDC) National Center for Health Statistics (NCHS) death data show that ~1,000 children younger than 15 years of age died from arthritis and other rheumatic conditions in the 20 years from 1979–1998 (average = 50 deaths / year).2 The juvenile AORC death rate fell 25% during the 20-year period from 1.2 per million to 0.9 per million (average = 1 death per million children per year).
The juvenile AORC death rate fell 25% during the 20-year period from 1.2 per million to 0.9 per million (average = 1 death per million children per year).2
Using a case definition (surveillance of pediatric arthritis and other rheumatologic conditions–SPARC) developed by CDC for ICD-9-CM based data systems approximately 61,800 children younger than age 17 were discharged from a hospital with at least 1 SPARC code annually. Children younger than age 6 accounted for 45% of SPARC discharges. Mean length of stay was 8.6 days.1
Depending on the specific condition, the impact on quality of life can be considerable. For example, for systemic type JIA, about 50% of cases develop short stature (<95th percentile) in adulthood. Overall, about 30% of people with JIA had significant functional limitations 10 or more years after onset.1
Lovell DJ. Juvenile Idiopathic Arthritis A. Clinical features in Primer on the Rheumatic Diseases. 13th edition, Klippel JH, Stone JH, Crofford LJ and White PH editors. Atlanta, GA: Springer: 2008.
Sacks JJ, Helmick CG, Langmaid G. Deaths from arthritis and other rheumatic conditions, United States, 1979–1998. J Rheumatol. 2004;31:1823–1828.
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 Care Res. 2007;57(8):1439–1445.