Characteristics of children included in the study with RF and/or anti-CCP positive JIA based on ILAR classification. 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 no. | 34 | 22 | |
| Age at symptom onset, yrs, mean ± SD | 10.3 ± 3.4 | 7.7 ± 4.3 | 0.023 |
| Age at diagnosis, yrs, mean ± SD | 11.3 ± 3.3 | 8.3 ± 4.6 | 0.012 |
| Demographic features | |||
| Female sex | 29 (85) | 15 (68) | 0.13 |
| Hispanic ethnicity | 8 (25) | 1 (5) | 0.07 |
| African ancestry | 11 (37) | 7 (32) | 0.72 |
| RF value, mean (range) | 259.4 (11–1741) | 44.7 (0–369) | 0.019 |
| Anti-CCP value, mean (range) | 185.0 (0– >448) | 118.6 (0– >250) | 0.022 |
| ILAR category | |||
| RF+ poly | 34 (100) | 0 (0) | |
| RF− poly | 0 (0) | 6 (27) | |
| Oligo extended | 0 (0) | 2 (9) | |
| Oligo persistent | 0 (0) | 4 (18) | |
| Undifferentiated | 0 (0) | 10 (45) | |
| Positive ANA | 12 (38) | 11 (52) | 0.29 |
| Meets ACR criteria for RA | 34 (100) | 16 (73) | 0.002 |
| Number of affected joints in first 6 mo, mean (range) | 13 (5–30) | 10 (2–48) | 0.38 |
| Treatment | |||
| Use of systemic steroids | 21 (62) | 8 (36) | 0.06 |
| Use of DMARD | 32 (94) | 18 (82) | 0.20 |
| Use of biologic | 21 (62) | 7 (32) | 0.029 |
| Elevated ESR within 3 mos of diagnosis | 24 (71) | 13 (65) | 0.67 |
| Elevated CRP within 3 mos of diagnosis | 18 (86) | 4 (36) | 0.013 |
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; ANA: antinuclear antibody; RA: rheumatoid arthritis; DMARD: disease-modifying antirheumatic drug.