Serum IGF-1 levels (mean and 95% CI) among subjects with increasing number of disease severity factors (CRP > 0.5 mg/dl, SvdH > 23, HAQ > 0, disease duration > 10 yrs, SJC > 1), adjusted for age and sex. IGF-1: insulin-like growth factor 1; CRP: C-reactive protein; SvdH: Sharp/van der Heijde method; HAQ: Health Assessment Questionnaire; SJC: swollen joint count.