Version July 2025
INTRODUCTION —
Juvenile idiopathic arthritis (JIA) is the most common rheumatologic disease of childhood and includes a heterogeneous group of inflammatory arthritides. This topic will introduce the revised International League of Associations for Rheumatology (ILAR) classification criteria. It should be noted that these criteria are in place to promote accurate distinctions between subtypes of JIA to facilitate research and are not intended for use as diagnostic criteria [1].
The clinical manifestations and diagnosis of various types of JIA are discussed elsewhere:
●(See "Oligoarticular juvenile idiopathic arthritis".)
●(See "Polyarticular juvenile idiopathic arthritis: Clinical manifestations, diagnosis, and complications".)
●(See "Spondyloarthritis in children".)
●(See "Psoriatic juvenile idiopathic arthritis: Epidemiology, clinical manifestations, and diagnosis".)
●(See "Systemic juvenile idiopathic arthritis: Clinical manifestations and diagnosis".)
OVERVIEW —
Various classification criteria have been used over time to categorize patients with juvenile idiopathic arthritis (JIA). As with other types of classification criteria, their primary purpose is to facilitate research [1]. However, the International League of Associations for Rheumatology (ILAR) criteria are often used clinically and may help providers communicate about disease features, treatment options, and prognosis.
Starting in the mid-1990s, ILAR has met periodically to develop and refine classification criteria for JIA that are internationally accepted and applicable. ILAR's first published criteria are referred to as the Durban classification [2], while the revised set in 2001 is known as the ILAR classification criteria [3].
Prior to this, two terms to describe JIA were proposed in the mid- to late 20th century in an attempt to systematize the diverse group of juvenile arthritides:
●Juvenile rheumatoid arthritis – This categorization was favored in the United States. It notably excluded patients with spondyloarthropathy, psoriatic arthritis, and inflammatory bowel disease (IBD)-associated arthritis.
●Juvenile chronic arthritis – This categorization was favored in the United Kingdom. It included patients with spondyloarthropathy, psoriatic arthritis, and IBD-associated arthritis.
These classification schemes also differed in their definitions of chronicity [4]. The terms juvenile rheumatoid arthritis and juvenile chronic arthritis are not commonly used today but may be encountered in older studies that used this terminology.
REVISED ILAR JIA CLASSIFICATION CRITERIA —
The revised International League of Associations for Rheumatology (ILAR) criteria outline inclusion and exclusion criteria for six mutually exclusive subtypes of juvenile idiopathic arthritis (JIA) (table 1) [3].
Overview of categories and exclusion criteria — The revised ILAR criteria specify that JIA is a diagnosis of exclusion defined by the onset of arthritis before the 16th year of age in the absence of other medical causes [3]. Symptoms must also be chronic (ie, present for at least six weeks' duration) in every subtype of JIA except for systemic arthritis.
The categories of JIA under the ILAR classification are:
●Systemic arthritis (see 'Systemic arthritis' below)
●Oligoarthritis, persistent or extended (see 'Oligoarthritis, persistent or extended' below)
●Polyarthritis, rheumatoid factor (RF) positive or negative (see 'Polyarthritis, rheumatoid factor positive or negative' below)
●Psoriatic arthritis (see 'Psoriatic arthritis' below)
●Enthesitis-related arthritis (ERA) (see 'Enthesitis-related arthritis' below)
●Undifferentiated arthritis (see 'Undifferentiated arthritis' below)
These categories are mutually exclusive. Patients who meet criteria for multiple categories or who do not meet criteria for any category are classified as having undifferentiated arthritis.
To be classified as having a certain subtype of JIA, patients must meet inclusion criteria and not meet certain exclusion criteria, which vary depending on the subtype of JIA. Exclusion criteria include the following:
●A personal history of or first-degree relative affected by psoriasis. Patients meeting this criterion are excluded from all categories except for psoriatic arthritis and undifferentiated arthritis.
●A personal history of or first-degree relative affected by certain conditions (including ERA, ankylosing spondylitis, sacroiliitis with inflammatory bowel disease [IBD], reactive arthritis, and/or acute anterior uveitis). Patients meeting this criterion are excluded from all categories except for ERA and undifferentiated arthritis.
●Arthritis starting after six years of age in a male patient who is positive for human leukocyte antigen B27 (HLA-B27). Patients meeting this criterion are excluded from all categories except for ERA and undifferentiated arthritis.
●Positive testing for RF (defined as having a positive immunoglobulin M RF test on at least two occasions checked at least three months apart within the first six months of disease). Patients meeting this criterion are excluded from all categories except for polyarthritis and undifferentiated arthritis.
Systemic arthritis — Systemic arthritis (systemic JIA) is defined as the presence of arthritis in one or more joints and fever of at least two weeks' duration (with at least three days of a quotidian pattern), plus one or more of the following features:
●Evanescent erythematous rash
●Generalized lymphadenopathy
●Hepatomegaly and/or splenomegaly
●Serositis
A patient with systemic arthritis should not meet any of the exclusion criteria outlined above. Likewise, patients should not have another etiology of their fever and arthritis (eg, infection, polyarteritis nodosa). (See 'Overview of categories and exclusion criteria' above.)
More information on systemic JIA is provided separately:
●(See "Systemic juvenile idiopathic arthritis: Clinical manifestations and diagnosis".)
●(See "Systemic juvenile idiopathic arthritis: Complications".)
●(See "Systemic juvenile idiopathic arthritis: Treatment and prognosis".)
Oligoarthritis, persistent or extended — Oligoarthritis (oligoarticular JIA) is defined as arthritis affecting one to four joints during the first six months of disease. Patients with a persistent course continue to have one to four affected joints, while those with an extended course develop more extensive arthritis affecting five or more joints. Children with oligoarticular JIA should not meet any of the exclusion criteria outlined above. (See 'Overview of categories and exclusion criteria' above.)
Patients with oligoarticular JIA and a positive antinuclear antibody (ANA) represent the highest-risk group for the development of anterior uveitis. However, ANA positivity is not factored into the classification of JIA, and uveitis can occur in any subtype. (See "Juvenile idiopathic arthritis: Immunizations and complications", section on 'Chronic anterior uveitis'.)
More information on oligoarticular JIA is provided separately. (See "Oligoarticular juvenile idiopathic arthritis".)
Polyarthritis, rheumatoid factor positive or negative — Patients are categorized as having polyarthritis (polyarticular JIA) if they have five or more joints affected during the first six months of their disease. These patients are further subdivided by RF positivity, which is defined as having a positive immunoglobulin M RF test on at least two occasions (checked at least three months apart but within the first six months of disease). RF positivity tends to occur more frequently in adolescents and may portend a more chronic course of arthritis, resembling adult-onset rheumatoid arthritis. Children should not meet exclusion criteria outlined above with the exception of the criterion about RF positivity. (See 'Overview of categories and exclusion criteria' above.)
More information on polyarticular JIA is provided separately. (See "Polyarticular juvenile idiopathic arthritis: Clinical manifestations, diagnosis, and complications" and "Polyarticular juvenile idiopathic arthritis: Treatment and prognosis".)
Psoriatic arthritis — Psoriatic arthritis (psoriatic JIA) defines the group of patients who present with arthritis and psoriasis simultaneously or arthritis plus at least two of the following:
●Dactylitis
●Nail pitting or onycholysis
●Psoriasis in a first-degree relative
Children should not meet exclusion criteria outlined above with the exception of the criterion about psoriasis. (See 'Overview of categories and exclusion criteria' above.)
More information on psoriatic JIA is provided separately. (See "Psoriatic juvenile idiopathic arthritis: Epidemiology, clinical manifestations, and diagnosis" and "Psoriatic juvenile idiopathic arthritis: Management and prognosis".)
Enthesitis-related arthritis — Classification of ERA rests on the presentation of arthritis and enthesitis, or arthritis or enthesitis plus at least two of the following:
●The presence of or history of sacroiliac joint tenderness and/or inflammatory back pain
●HLA-B27 positivity
●Onset of arthritis in a male over six years of age
●Acute anterior uveitis
●History in a first-degree relative of ankylosing spondylitis, ERA, sacroiliitis with IBD, reactive arthritis, or acute anterior uveitis
Children should not meet exclusion criteria outlined above with the exception of the criteria related to HLA-B27 positivity and personal or family history of conditions related to ERA. (See 'Overview of categories and exclusion criteria' above.)
Clinically, patients in this category are often classified as having spondyloarthritis. More information on ERA is provided separately. (See "Spondyloarthritis in children".)
Undifferentiated arthritis — A patient is considered to have undifferentiated arthritis if they do not meet any of the above criteria or if they fulfill criteria for two or more categories.
APPLICABILITY AND LIMITATIONS OF THE ILAR CRITERIA —
The initial and revised International League of Associations for Rheumatology (ILAR) criteria have been validated in multiple international studies [5-7]. In one German study of 97 patients with juvenile idiopathic arthritis (JIA), 88 percent were able to be classified according to the Durban classification [5]. Similarly, a cohort of Spanish patients was studied, and 85 percent were classifiable under Durban criteria [6].
The main limitations of the ILAR criteria relate to the exclusion criteria. Challenges include the following:
●In both of the validation studies above, the most common cause for difficulty of classification was family history of psoriasis without other features of psoriatic arthritis [5,6]. There may be distinct subgroups of patients who are classified as having psoriatic JIA, including patients with early-onset disease who are antinuclear antibody (ANA) positive and patients who have features that are most suggestive of spondyloarthritis [8].
●A study from the United States identified misclassification of patients with rheumatoid factor (RF) negative, anticitrullinated C-peptide (CCP) positive polyarthritis who otherwise clinically most closely resemble RF-positive polyarthritis patients [9].
●Finally, it can be challenging to apply ILAR criteria to pediatric patients with axial spondyloarthropathy [10,11].
OVERLAP WITH THE CLASSIFICATION OF ADULT ARTHRITIS —
Some subtypes of juvenile idiopathic arthritis (JIA) appear to be unique to children; as an example, antinuclear antibody (ANA)-positive oligoarticular JIA complicated by uveitis does not have a clear counterpart in adults [12,13]. However, in clinical practice, many of the International League of Associations for Rheumatology (ILAR) JIA categories do have correlates in adult rheumatology, as summarized in the figure (figure 1) [13-15].
In a study that applied both pediatric and adult classification criteria for inflammatory arthritis to 130 patients with JIA who were transitioning to adult care, most patients with JIA met the respective adult classification criteria, with the exceptions of those with oligoarticular JIA and rheumatoid factor (RF)-negative polyarticular JIA [16]. Likewise, a study of 426 patients with JIA found that 79 percent met classification criteria for some type of adult arthritis; the percentage of patients who did not meet adult classification criteria was highest for those with oligoarticular JIA (59 percent for persistent oligoarticular JIA, 35 percent for extended), RF-negative JIA (24 percent), and undifferentiated arthritis (17 percent) [17]. The overlap in clinical presentations is somewhat expected given that choosing a cutoff of age 16 to differentiate pediatric and adult arthritis was explicitly arbitrary when it was first done in the 1950s and reflected a division in the medical system, not one in patient presentations or underlying pathophysiology [18,19].
Understanding these similarities and differences is important in clinical care, especially when caring for adult patients with JIA and identifying potential common pathways for treatment. There are ongoing efforts to further delineate overlapping and distinctive features between pediatric and adult arthritis in hopes of furthering advances in care [14]. (See 'Future directions' below.)
FUTURE DIRECTIONS —
The goal of further refining classification criteria is to define homogeneous groups of patients with biologically distinct illnesses in hopes of identifying distinct underlying pathophysiology and subsequent treatment approaches.
The Pediatric Rheumatology International Trial Organization (PRINTO) has initiated a study utilizing Delphi consensus and nominal group technique to identify new criteria for juvenile idiopathic arthritis (JIA) by expert consensus [14]. Proposed categories include:
●Systemic JIA
●Rheumatoid factor (RF)-positive JIA
●Enthesitis/spondylitis-related JIA
●Early-onset antinuclear antibody (ANA)-positive JIA
●Other JIA (not meeting criteria for any of the preceding four categories)
●Unclassified JIA (meeting criteria for more than one of the preceding categories)
Notably, under these proposed criteria, patients may be diagnosed with JIA if symptom onset occurs before the age of 18 years.
It is unclear whether the PRINTO categories offer significant advantages when compared with those of the International League of Associations for Rheumatology (ILAR) classification system. In a comparison of the PRINTO and ILAR classifications in a North American cohort of 1228 patients with JIA, many more patients were unclassifiable using the PRINTO categories (63 versus 12 percent, respectively) [20]. A study in the United Kingdom similarly found that while there was strong overlap between the PRINTO enthesitis/spondylitis-related JIA and ILAR enthesitis-related JIA categories, the majority of JIA patients could not classified using the PRINTO criteria [21]. Moreover, the alignment with the classification of adult arthritis and proposed clinicobiologic subtypes of JIA [22] were not any better with PRINTO versus ILAR classification schemes.
In addition to refining JIA categories through expert consensus, there are ongoing efforts to refine our understanding of the biologic basis for subtypes of JIA through advanced research in genetics and immunology. Advances in computational biology over the last decade have allowed researchers to develop biologically distinct groupings of patients who share immunologic and clinical features with a higher degree of concordance compared with conventional criteria [22]. As an example, in an inception cohort of 150 patients with newly diagnosed JIA, principal component analysis was used to prospectively group clusters of patients based on clinical features and inflammatory biomarkers; they found that the newly identified clusters spanned the current JIA subtypes and revealed pathobiologic similarities that are not reflected by current classification [23]. Other efforts examining arthritis across the age span have suggested that there may be human leukocyte antigen (HLA) and non-HLA susceptibility loci common to JIA and adult arthritis [24-27].
SOCIETY GUIDELINE LINKS —
Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Juvenile idiopathic arthritis".)
INFORMATION FOR PATIENTS —
UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Juvenile idiopathic arthritis (The Basics)")
SUMMARY
●Overview – The classification of juvenile idiopathic arthritis (JIA) is challenging given the heterogeneity of the disease. Classification criteria are intended for use in the research setting. However, the International League of Associations for Rheumatology (ILAR) criteria are often used clinically and may have utility in helping providers communicate about disease features, treatment options, and prognosis. (See 'Introduction' above and 'Overview' above.)
●ILAR classification categories for JIA – The ILAR classification criteria define JIA as arthritis occurring before 16 years of age in the absence of other medical causes, with persistent clinical symptoms for at least six weeks. It is a diagnosis of exclusion. (See 'Revised ILAR JIA classification criteria' above.)
The mutually exclusive categories of JIA under the ILAR classification are (table 1):
•Systemic arthritis (see 'Systemic arthritis' above)
•Oligoarthritis, persistent or extended (see 'Oligoarthritis, persistent or extended' above)
•Polyarthritis, rheumatoid factor (RF) positive or negative (see 'Polyarthritis, rheumatoid factor positive or negative' above)
•Psoriatic arthritis (see 'Psoriatic arthritis' above)
•Enthesitis-related arthritis (ERA) (see 'Enthesitis-related arthritis' above)
•Undifferentiated arthritis (see 'Undifferentiated arthritis' above)
●Applicability and limitations of ILAR classification criteria – The ILAR criteria have been validated in multiple international studies. They can be challenging to apply to pediatric patients with axial spondyloarthropathy and may also misclassify some patients, including those with a family history of psoriasis without clinical features suggestive of psoriatic JIA and those with rheumatoid factor (RF)-negative, anticitrullinated C-peptide (CCP)-positive polyarthritis. (See 'Applicability and limitations of the ILAR criteria' above.)
●Overlap with the classification of adult arthritis – Some presentations of JIA appear to be unique to children, while others have correlates in adult rheumatology (figure 1). Understanding these similarities and differences is important in clinical care, especially when caring for adult patients with JIA and identifying potential common pathways for treatment. (See 'Overlap with the classification of adult arthritis' above.)
●Future directions – The goal of further refining classification criteria is to define homogeneous groups of patients with biologically distinct illnesses. The ILAR criteria are considered the standard and other proposed systems still require further validation, including the Pediatric Rheumatology International Trial Organization (PRINTO) categories for JIA. (See 'Future directions' above.)
ACKNOWLEDGMENT —
The editorial staff at UpToDate acknowledge Thomas JA Lehman, MD and Sarah Ringold, MD, MS, who contributed to earlier versions of this topic review.
