ABSTRACT
An international consensus conference was convened in 1997 to agree on nomenclature. The American College of Rheumatology (ACR) classification criteria are currently the only ones with corresponding ICD-9 codes in the United States. The three most widely used criteria, the ILAR classification, the ACR, and the European League Against Rheumatism (EULAR), are compared (Table 1) (Brewer et al. 1972, European League Against Rheumatism 1977, Petty et al. 1997). The ILAR classification includes the HLA-B27-associated spondyloarthropathies and psoriatic arthritis, subtypes categorized separately by the ACR criteria and covered in a different chapter in this handbook.
