Oligoarticular JIA (oligoarthritis): Up to 60 out of 100 children with JIA have this form.2 They may continue to have the disease as adults. This risk is higher if more joints are affected after the first 6 months.
Polyarticular JIA (polyarthritis): This type of JIA is more severe than most cases of oligoarticular JIA. That's because polyarticular JIA affects more joints, and it tends to get worse over time. About 30 out of 100 children affected by JIA have this form.2 Many children will have active disease that continues into adulthood. There are two types: rheumatoid factor-positive (RF-positive) and rheumatoid factor-negative (RF-negative).
Systemic JIA: About 10 out of 100 children affected by JIA have the systemic form.2 Many will continue to have active disease as adults. While some children have one course of this disease that lasts 2 to 4 years, others continue to have mild joint pain and flares of other symptoms. A few have ongoing destructive arthritis, often into adulthood, even with treatment.2
Enthesitis-related JIA: About 10 out of 100 children with JIA have this form. The long-term outlook for this form of JIA is less well known. Some children progress to other conditions such as adult ankylosing spondylitis. This is more common in boys who have hip arthritis.
Psoriatic JIA: This is the least common form, occurring in fewer than 10 out of 100 children with JIA. Children with psoriatic arthritis have a skin condition called psoriasis. The long-term outcome for this type of JIA isn't well known. Some children continue to have skin and joint symptoms. For a few, the ability to do daily activities can become limited.
Joint damage. This is common in the polyarticular form of JIA and can occur early. About 30 to 50 out of 100 children with JIA may have some level of disability that continues into adulthood.2 Long-term problems can be mild and have little effect on daily activities.
Some children with polyarthritis get arthritis in the neck that can cause the neck bones to fuse together.