Subgroup analysis of children with RF+ poly JIA compared to other categories. Data from children with RF-negative, anti-CCP positive JIA are excluded. All values are n (%) of those tested/reporting data for particular variables, except as indicated.
| RF+ poly JIA, n (%) | All other Categories, n (%) | p | |
|---|---|---|---|
| Total number | 34 | 10 | |
| Age at symptom onset, yrs, mean ± SD | 10.3 ± 3.4 | 10.2 ± 2.8 | 0.89 |
| Age at diagnosis, yrs, mean ± SD | 11.3 ± 3.3 | 11.1 ± 3.1 | 0.84 |
| Demographic features | |||
| Female | 29 (85) | 6 (60) | 0.17 |
| Hispanic ethnicity | 8 (25) | 1 (10) | 0.32 |
| African ancestry | 11 (37) | 3 (30) | 1.00 |
| Anti-CCP value, mean (range) | 185.0 (24–> 448) | 226.8 (> 60–> 250) | 0.04 |
| RF value, mean (range) | 259.4 (11–> 448) | 96.2 (0–346) | 0.004 |
| ILAR category | |||
| RF+ poly | 34 (100) | 0 | |
| RF− poly | 0 (0) | 0 | |
| Oligo extended | 0 (0) | 0 | |
| Oligo persistent | 0 (0) | 0 | |
| Undifferentiated | 0 (0) | 10 (100) | |
| Meets ACR criteria for RA | 34 (100) | 10 (100) | 1.00 |
| Number of affected joints in first 6 mos, mean, (range) | 13 (5–30) | 8 (2–25) | 0.14 |
| Treatment | |||
| Use of systemic steroids | 21 (62) | 5 (50) | 0.51 |
| Use of DMARD | 32 (94) | 10 (100) | 1.00 |
| Use of biologic | 21 (62) | 6 (60) | 1.00 |
| Elevated ESR within 3 mos of diagnosis | 24 (71) | 6 (67) | 1.00 |
| Elevated CRP within 3 mos of diagnosis | 18 (86) | 2 (33) | 0.02 |
p values in boldface are statistically significant. Most common upper limit of normal for RF = 13.9. Most common interpretation of anti-CCP values: < 20 negative; 20–39 weak positive; 40–59 moderate/strong positive; > 59 strong positive. DMARD: methotrexate (oral or subcutaneous), plaquenil, sulfasalazine. Biologics: etanercept, adalimumab, anakinra, abatacept, infliximab. ACR: American College of Rheumatology; RF: rheumatoid factor; anti-CCP: anticyclic citrullinated peptide antibodies; CRP: C-reactive protein; ESR: erythrocyte sedimentation rate; ILAR: International League of Associations for Rheumatology; RA: rheumatoid arthritis; DMARD: disease-modifying antirheumatic drug; JIA: juvenile idiopathic arthritis.