CRP and juvenile idiopathic arthritis: JIA, juvenile idiopathic arthritis; RF: rheumatoid factor; CRP: C-reactive protein; ESR: erythrocyte sedimentation rate; CHAQ: Childhood Health Assessment Questionnaire; ETN: etanercept; MTX: methotrexate; LEF: leflunomide; DMARDs: disease-modifying antirheumatic drugs.