Table 1.

Core variables currently endorsed by the ACR for the assessment of patients with JIA, and current proposed definitions for disease improvement, flare, inactive disease, and disease remission.

ACR core variables¹²	physician global assessment of disease activity parent/patient assessment of overall well-being functional ability (often assessed with the CHAQ) number of joints with active arthritis number of joints with limited range of motion ESR (or CRP)
Definition of improvement	At least 30% improvement from baseline in 3 of any 6 variables in the core set, with no more than 1 of the remaining variables worsening by > 30%.
Definition of flare	Worsening of at least 3 of the 6 ACR core measures by at least 30% without concomitant improvement of more than 1 core measure by 30% or more.
Definition of clinical inactive disease¹³	No joints with active arthritis.
	No fever, rash, serositis, splenomegaly, or generalized lymphadenopathy attributable to JIA.
	No active uveitis as defined by the Standardization of Uveitis Nomenclature Working Group.
	ESR or CRP level within normal limits in the laboratory where tested or, if elevated, not attributable to JIA.
	Physician global assessment of disease activity score of best possible on the scale used.
	Duration of morning stiffness of 15 min or less.
Definition of clinical remission	Remission on medication: a minimum of 6 continuous mos of inactive disease while receiving medication.
Definition of clinical remission	Remission off medication: 12 mos of inactive disease while not receiving any antiarthritis or antiuveitis medication.

ACR: American College of Rheumatology; JIA: juvenile idiopathic arthritis; CHAQ: Child Health Assessment Questionnaire; ESR: erythrocyte sedimentation rate; CRP: C-reactive protein.