Table 1.
Characteristics of the study population as a whole (n=851) and stratified by pain trajectory
| Variable | Available data, n (% missing) |
All patients | Consistently low pain, n=453 (50.2%) |
Improved pain, n=254 (31.9%) |
Consistently high pain, n=144 (17.9%) |
| Baseline | |||||
| Age, years* | 847 (0.5) | 7.6 (3.6–11.8) | 6.3 (2.9–10.9)†‡ | 8.6 (3.7–12.3)†§ | 10.8 (6.5–13.2)‡§ |
| Age at onset, years* | 843 (0.9) | 6.6 (2.7–10.8) | 5.6 (2.4–9.9)†‡ | 7.0 (3.0–11.1)†§ | 9.3 (4.5–11.8)‡§ |
| Gender n (%¶) | 851 (0.0) | ||||
| Female | 562 (66.0) | 288 (63.6)** | 184 (72.4)** | 90 (62.5)** | |
| Male | 289 (34.0) | 165 (36.4) | 70 (27.6) | 54 (37.5) | |
| Disease duration, months* | 839 (1.4) | 5.3 (2.7–10.7) | 4.7 (2.3–8.5)†‡ | 5.8 (2.8–12.8) †§ | 6.9 (3.7–17.6)‡§ |
| Disease duration from referral, weeks* | 793 (6.8) | 4 (1.3–7.7) | 4 (1.4–7.7) | 3.4 (1–7.1) | 4.6 (1.3–8.1) |
| PGA, cm* | 600 (29.5) | 3 (1.8, 5.4) | 2.6 (1.4, 4.8)†‡ | 3.5 (2, 5.7)† | 3.3 (2.1, 5.8)‡ |
| AJC* | 780 (8.3) | 2 (1–6) | 2 (1, 5)†‡ | 3 (1, 8)† | 3 (1, 8)‡ |
| PGE, cm* | 834 (2.0) | 2.1 (0.5, 5) | 0.8 (0.1, 2.4)†‡ | 4.6 (2.2, 6.2)† | 4.1 (2, 6.35)‡ |
| Pain, cm* | 851 (0.0) | 3 (0.8, 5.7) | 1 (0.2, 2.5)†‡ | 6 (4.5, 7.4)†§ | 5 (3, 6.9)‡§ |
| CHAQ* | 849 (0.2) | 0.6 (0.1–1.4) | 0.3 (0–0.9)†‡ | 1.1 (0.6–1.8)† | 1.1 (0.6–1.8)‡ |
| MFQ* | 312 (63.3) | 13 (6, 23) | 9 (4, 16) | 17 (9, 27) | 21 (13, 27) |
| Early change | |||||
| DMARDs 1st year n (%¶) | 851 (0.0) | ||||
| No | 434 (51) | 274 (60.5)** | 101 (39.8)** | 59 (41.0)** | |
| Yes | 417 (49) | 179 (39.5) | 153 (60.2) | 85 (59.0) | |
| Number of DMARDs 1st year n (%¶) | 851 (0.0) | ||||
| 1 | 381 (91.4) | 169 (94.4)** | 141 (92.2)** | 71 (83.5)** | |
| 2 | 31 (7.4) | 8 (4.5) | 10 (6.5) | 13 (15.3) | |
| 3 | 5 (1.2) | 2 (1.1) | 2 (1.3) | 1 (1.2) | |
| Biologics 1st year n (%¶) | 851 (0.0) | ||||
| No | 769 (90.4) | 430 (94.9)** | 222 (87.4)** | 117 (81.3)** | |
| Yes | 82 (9.6) | 23 (5.1) | 32 (12.6) | 27 (18.7) | |
| Number of biologics 1st year n (%¶) | 851 (0.0) | ||||
| 1 | 75 (91.5) | 22 (95.6) | 28 (87.5) | 25 (92.6) | |
| 2 | 6 (7.3) | 1 (4.4) | 3 (9.4) | 2 (7.4) | |
| 3 | 1 (1.2) | 0 (0) | 1 (3.1) | 0 (0.0) | |
| All steroids 1st year n (%¶) | 851 (0.0) | ||||
| No | 207 (24.3) | 118 (26.1) | 56 (22.1) | 33 (22.9) | |
| Yes | 644 (75.7) | 335 (73.9) | 198 (77.9) | 111 (77.1) | |
| Change in AJC 6 months, cm*†† | 541 (36.4) | −1 (−4, 0) | −1 (−3, 0) | −1 (−5, 0) | −1 (−4, 0) |
| Change in PGA 6 months, cm*†† | 390 (54.2) | −1.9 (−3.9, –0.5) | −1.9 (−4.2, –0.7) | −1.9 (−3.4, –0.3) | −1.8 (−3.9, –0.2) |
| Change in PGE 6 months, cm*†† | 500 (41.2) | −0.5 (–2.4, 0.3) | −0.3 (–0.2, 0.1) | −1.2 (–3.5, 0.6)§ | −0.1 (–2, 1.5)§ |
| Change in CHAQ 1 year*†† | 702 (17.7) | −0.1 (–0.6, 0) | −0.1 (–0.6, 0)†‡ | −0.4 (–1, 0)†§ | 0 (–0.5, 0.4)‡§ |
| Change in pain 1 year, cm*†† | 691 (18.8) | −0.7 (–3.2, 0.2) | −0.4 (–1.9, 0)†‡ | −3.2 (–5.8, –0.3)†§ | 0.5 (–1.7, 2.6)‡§ |
All values are median (IQR) unless stated.
*Multiple comparisons of significant differences between trajectory groups using an adjusted P≤0.0083 from Kruskal-Wallis tests. n, number of children.
†Improved pain versus consistently low pain.
‡Consistently high pain versus consistently low pain.
§Consistently high pain versus improved pain.
¶Column.; PGA, Physician’s global assessment PGE, Parent’s/patient’s general evaluation of wellbeingwell-being VAS, visual analogue scale; CHAQ, Childhood Health Assessment Questionnaire.
**P≤0.05 from χ2 indicates a significant difference in proportions between the three trajectory groups.
††Minus denotes a decrease in the covariate.
AJC, active joint count; CHAQ, Childhood Health Assessment Questionnaire; n, number of children; nr, not reported; ns, non-significant; PGA, Physician’s Global Assessment; PGE, parent’s/patient’s general evaluation of well-being; VAS, visual analogue scale.