Baseline characteristics of children in each of the 4 juvenile idiopathic arthritis (JIA) disease course groups. Numbers are median and (25th, 75th centiles), unless otherwise specified. Median scores for patient-reported outcomes are after imputation of missing values.
| Characteristics | Mild, n = 267 | Moderate, n = 217 | Severe Controlled, n = 55 | Severe Persistent, n = 70 | p* | All Subjects, n = 609 Missing | Subjects Data (%) ** |
|---|---|---|---|---|---|---|---|
| Age at diagnosis, yrs | 7.5 (3.2, 7.5) | 7.6 (2.8, 11.6) | 10.9 (5.5, 12.8) | 11.4 (7.3, 13.1) | 0.0001 | 8.4 (3.4, 11.9) | 7 (1.1) |
| Female, n (%) | 171 (64.0) | 154 (71.3) | 42 (76.4) | 46 (65.7) | 0.18 | 413 (67.9) | 1 (0.2) |
| JADAS3 | 4.7 (2.4, 8.2) | 9.7 (5.3, 14.8) | 20.1 (16.8, 22.8) | 12.3 (7.8, 18.8) | 0.0001 | 7.9 (3.9, 14.3) | 84 (13.8) |
| JIA category (column %, row %) | < 0.001 | 0 (0) | |||||
| Oligoarthritis | 155 (58.0, 69.5) | 59 (27.2, 26.5) | 1 (1.8, 0.4) | 8 (11.4, 3.6) | 223 (36.6, 100) | ||
| RF-negative polyarthritis | 28 (10.5, 21.7) | 57 (26.3, 44.2) | 27 (49.1, 20.9) | 17 (24.3, 13.2) | 129 (21.2, 100) | ||
| Enthesitis-related | 31 (11.6, 38.3) | 26 (12.0, 32.1) | 7 (12.7, 8.6) | 17 (24.3, 21.0) | 81 (13.3, 100) | ||
| Systemic | 12 (4.5, 25.5) | 25 (11.5, 53.2) | 4 (7.3, 8.5) | 6 (8.6, 12.8) | 47 (7.7, 100) | ||
| Psoriatic | 14 (5.2, 38.9) | 18 (8.3, 50.0) | 1 (1.8, 2.8) | 3 (4.3, 8.3) | 36 (5.9, 100) | ||
| RF-positive polyarthritis | 1 (0.4, 3.8) | 5 (2.3, 19.2) | 13 (23.6, 50.0) | 7 (10.0, 26.9) | 26 (4.3, 100) | ||
| Undifferentiated | 26 (9.7, 38.8) | 27 (12.4, 40.3) | 2 (3.6, 3.0) | 12 (17.1, 17.9) | 67 (11.0, 100) | ||
| Active joints (%) | 3 (0.5) | ||||||
| Cervical spine | 3 (1.1) | 5 (2.3) | 14 (25.4) | 7 (10.0) | < 0.001 | 29 (4.8) | |
| Wrist | 31 (11.6) | 66 (30.4) | 51 (92.7) | 30 (42.9) | < 0.001 | 178 (29.2) | |
| Finger joints | 48 (18.0) | 74 (34.1) | 53 (96.4) | 33 (47.1) | < 0.001 | 208 (34.1) | |
| Hip | 10 (3.7) | 24 (11.1) | 21 (38.2) | 14 (20.0) | < 0.001 | 69 (11.3) | |
| Ankle | 59 (22.1) | 81 (37.3) | 46 (83.6) | 32 (45.7) | < 0.001 | 218 (35.8) | |
| Monoarthritis (%) | 96 (36.0) | 40 (18.4) | 0 | 8 (11.4) | < 0.001 | 144 (23.6) | 3 (0.5) |
| Symmetric (%) | 70 (26.2) | 106 (48.8) | 55 (100) | 42 (60) | < 0.001 | 273 (44.8) | 3 (0.5) |
| Enthesitis (%) | 22 (8.2) | 15 (6.9) | 6 (10.9) | 14 (20.0) | 0.01 | 8.9 | 5 (0.8) |
| Laboratory | |||||||
| ANA-positive | 136 (50.9) | 97 (44.7) | 24 (43.6) | 30 (42.9) | 0.392 | 287 (47.1) | 57 (9.4) |
| B27-positive | 25 (9.4) | 21 (9.7) | 6 (10.9) | 12 (17.1) | 0.285 | 64 (10.5) | 372 (61) |
| RF-positive *** | 6 (2.2) | 15 (6.9) | 14 (25.4) | 10 (14.3) | < 0.001 | 45 (7.4) | 87 (14.3) |
| Hemoglobin, g/l | 122 (114, 130) | 120 (111, 128) | 120 (114, 131) | 120 (114, 131) | 0.168 | 29 (4.8) | |
| Sedimentation rate, mm/h | 20 (9, 34) | 23 (11, 40) | 20 (9, 49) | 21 (9, 41) | 0.212 | 20 (9, 38) | 57 (9.4) |
| Patient/parent report | 84 (13.8) | ||||||
| Pain, cm | 1.6 (0.5, 3.0) | 3.3 (1.6, 5.7) | 4.0 (2.1, 6.7) | 4.9 (2.7, 6.7) | 0.0001 | 2.7 (0.7, 5.5) | |
| Quality of My Life Score Questionnaire | 8.8 (7.5, 9.7) | 7.4 (5, 8.9) | 7.3 (4.5, 8.6) | 4.5 (3.2, 5.9) | 0.0001 | 8 (5.2, 9.5) | |
| Parent global, cm | 0.8 (0.1, 1.8) | 2.3 (1.0, 4.4) | 3.0 (1.3, 5.5) | 3.8 (2.0, 5.4) | 0.0001 | 1.6 (0.4, 4) | |
| JAQQ score | 2.2 (1.6, 2.8) | 3.1 (2.2, 4.1) | 4.1 (3.0, 5.0) | 3.7 (2.7, 4.7) | 0.0001 | 2.7 (1.9, 3.9) | |
| CHAQ score | 0.2 (0, 0.5) | 0.5 (0.2, 1.0) | 1.0 (0.3, 1.4) | 0.8 (0.2, 1.4) | 0.0001 | 0.4 (0.1, 0.9) | |
| Physician report | 3 (0.5) | ||||||
| PGA, cm | 1.8 (0.8, 3.4) | 3.0 (1.7, 5.4) | 6.7 (5.6, 7.9) | 4.0 (1.6, 6.2) | 0.0001 | 2.8 (1.1, 5.3) | |
| Active-joint count | 1 (1, 2) | 3 (1, 6) | 27 (20, 36) | 5 (1, 13) | 0.0001 | 2 (1, 6) | |
| Limited-joint count | 1 (0, 2) | 2 (0, 4) | 10 (3, 19) | 2 (0, 5) | 0.0001 | 1 (0, 3) |
↵* Probability that the difference observed across the 4 clusters is due to chance alone calculated with chi-square test for proportions and with Kruskal-Wallis test for medians. For JIA categories, a single chi-square test with 7 levels/categories was used.
↵** No. and proportion of subjects with missing data at enrollment. Laboratory testing was done only when clinically indicated and some laboratory tests may have been done at later visits.
↵*** A positive test for rheumatoid factor (RF). This is different from RF-positive polyarthritis, because that JIA category requires involvement of 5 or more joints and 2 positive tests for RF at least 3 months apart. JADAS3: 3-variable Juvenile Arthritis Disease Activity Score (the sum of physician’s global assessment, parent’s global assessment, and up to 10 active joints); ANA: antinuclear antibodies; B27: HLA-B27 was present; JAQQ: Juvenile Arthritis Quality of Life Questionnaire; CHAQ: Childhood Health Assessment Questionnaire; PGA: physician’s global assessment of disease activity.