Comparison of international league of associations for rheumatology and pediatric rheumatology international trials organization classification criteria for juvenile idiopathic arthritis: insights from an African multicenter cohort.

The International League of Associations for Rheumatology (ILAR) classification criteria for juvenile idiopathic arthritis (JIA) are currently widely used in clinical practice. However, new criteria have recently been proposed by the Pediatric Rheumatology International Trials Organization (PRINTO) and are still under validation. The objective of this study is to compare the ILAR and PRINTO classifications when applied to an African multicenter cohort. We included patients under 18 years of age diagnosed with JIA according to ILAR criteria from the Pediatric African League Against Rheumatism (PAFLAR) registry. Subtypes were reassigned based on PRINTO criteria. Overlaps were assessed using Circos plots and chi-square tests. Overrepresented pairs were defined as those with Z scores ≥ 1.96. Cohen's Kappa was used to assess agreement. A total of 316 patients were included (sex ratio H/F = 0.69; mean age 8.8 ± 4.4 years). ILAR undifferentiated arthritis and PRINTO other JIA accounted for 11.7% and 63% of cases, respectively. Significant overlap was observed between the following ILAR and PRINTO subtypes: rheumatoid factor (RF)-positive polyarthritis/RF-positive JIA (Z = + 14.7), systemic arthritis/systemic JIA (Z = + 13.1), enthesitis-related arthritis (ERA)/enthesitis-spondylitis-related arthritis (Z = + 8.6), oligoarthritis/early-onset antinuclear antibody (ANA)-positive JIA (Z = + 3.7), RF-negative polyarthritis/other JIA (Z = + 2.5), and oligoarthritis/other JIA (Z = + 2.1). The agreement was almost perfect for systemic JIA (κ = 0.864) and RF-positive JIA (κ = 0.885).

conclusionThe PRINTO classification did not reduce the number of unclassifiable cases. Nearly two-thirds of our patients were classified as PRINTO "other JIA". However, it may allow better delineation of homogeneous subgroups, such as early-onset ANA-positive and RF-positive JIA. WHAT IS KNOWN: • The ILAR classification criteria are the most widely used system for categorizing JIA, but it has some limitations, notably the existence of heterogeneous and unclassifiable subgroups. • The PRINTO group proposed new classification criteria to overcome ILAR shortcomings and align pediatric forms of arthritis with adult ones. WHAT IS NEW: • The PRINTO classification did not reduce the number of unclassifiable JIA patients. Two-thirds of the patients remained unclassified using PRINTO criteria. • African JIA patients had a higher frequency of the ERA subtype, common hip involvement, and lower detection of cutaneous rash.