Chapter 15 - POLYARTHRITIS

Chronic childhood arthritis affecting more than four joints during the first 6 months of disease is defined as polyarthritis.1,2 In the classification of the International League of Associations for Rheumatology (ILAR),2 polyarthritis is further categorized as rheumatoid factor (RF) negative if tests for RF are negative, and RF positive if RF is detected on two occasions at least three months apart (Table 15–1). Consequently, this chapter considers RFnegative and RF-positive polyarthritis juvenile idiopathic arthritis (JIA) subsets separately, as distinctive clinical entities.