Clinical manifestations and assessments from study enrolment until year 4
| Clinical parameter* | At study enrolment n=118 | Month 6 n=117 | Year 1 n=114 | Year 2 n=104 | Year 3 n=93 | Year 4 n=68 | p Value |
|---|---|---|---|---|---|---|---|
| Current status | |||||||
| Arthritis, n (%) | 89 (75.4) | 60 (51.3) | 44 (38.6) | 19 (17.8) | 13 (14) | 12 (17.6) | 0.0001 |
| Arthritis joint count (0–64), mean (SD) | 2.0 (2.3) | 1.3 (2.1) | 1.0 (1.8) | 0.4 (1.1) | 0.3 (0.7) | 0.5 (1.1) | 0.0001 |
| Joints with limited range of motion, n (%) | 70 (59.3) | 63 (53.8) | 57 (50) | 33 (30.8) | 23 (24.7) | 28 (41.2) | 0.615 |
| Joints with limited range of motion, mean (SD) | 1.5 (1.4) | 1.4 (1.6) | 1.3 (1.4) | 0.9 (1.4) | 0.9 (1.6) | 1.1 (1.2) | 0.015 |
| Enthesitis, n (%) | 19 (16.1) | 11 (9.4) | 12 (10.5) | 6 (5.6) | 2 (2.2) | 2 (2.9) | 0.079 |
| Enthesitis count (0–12), mean (SD) | 0.3 (0.8) | 0.1 (0.5) | 0.2 (0.6) | 0.1 (0.5) | 0.02 (0.1) | 0.1 (0.6) | 0.513 |
| Inflammatory back pain, n (%) | 23 (19.7) | 16 (14.5) | 11 (10.9) | 14 (16.9) | 8 (11.9) | 7 (13.7) | 0.58 |
| Patient's global assessment (0–10 NRS), mean (SD) | n.d. | 2.9 (2.6) | 2.1 (2.2) | 2.2 (2.7) | 1.8 (2.3) | 2.3 (2.9) | 0.006 |
| Pain (0–10 NRS), mean (SD) | 2.5 (2.3) | 1.9 (2.1) | 1.5 (1.8) | 1.6 (2.3) | 1.4 (2.1) | 1.3 (1.9) | 0.244 |
| ASDAS (0–10), mean (SD) | n.d. | 1.6 (0.7) | 1.4 (0.7) | 1.4 (0.8) | 1.4 (0.8) | 1.3 (0.6) | 0.092 |
| BASDAI (0–10), mean (SD) | 2.0 (1.7) | 1.6 (1.5) | 1.3 (1.3) | 1.4 (1.4) | 1.1 (1.1) | 1.0 (1.1) | 0.002 |
| BASFI (0–10), mean (SD) | 0.7 (1.0) | 0.6 (1.0) | 0.4 (0.7) | 0.4 (0.9) | 0.3 (0.6) | 0.3 (0.5) | 0.002 |
| CHAQ (0–3), mean (SD) | 0.2 (0.3) | 0.2 (0.4) | 0.1 (0.2) | 0.1 (0.3) | 0.1 (0.2) | 0.1 (0.2) | 0.0001 |
| KINDL (0–100), mean (SD) | 76 (12.3) | 77 (12.3) | 79 (11.8) | 80 (11.8) | 81 (13.0) | 82 (11.9) | 0.165 |
| Current or within the past 6 months | |||||||
| Arthritis, n (%) | 113 (95.8) | 83 (70.9) | 60 (52.6) | 30 (28) | 17 (18.3) | 15 (22.1) | 0.0001 |
| Enthesitis, n (%) | 52 (44.1) | 28 (23.9) | 20 (17.5) | 10 (9.3) | 4 (4.3) | 2 (2.9) | 0.0001 |
| Inflammatory back pain, n (%) | 38 (32.2) | 20 (18.2) | 14 (13.9) | 19 (22.9) | 11 (16.4) | 9 (16.7) | 0.495 |
| Physician’s global assessment (0–10 NRS), mean (SD) | 2.0 (1.5) | 1.6 (1.3) | 1.4 (1.3) | 1.3 (1.3) | 0.9 (1.0) | 1.0 (1.1) | 0.0003 |
| Uveitis, n (%) | 8 (6.8) | 2 (1.7) | 3 (2.6) | 1 (0.9) | 1 (1.1) | 4 (5.9) | 0.07 |
| Remission on medication, n (%) | 0 (0) | 6 (5.6) | 10 (10.4) | 21 (25.6) | 23 (34.8) | 23 (43.4) | 0.0001 |
| Remission off medication, n (%) | – | 0 (0) | 2 (2.1) | 3 (3.7) | 7 (10.6) | 12 (22.6) | 0.0004 |
*In the case of mean changes, mixed linear models were used to test changes over time. Generalised equation models were used to analyse changes over time for percentages.
BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Ankylosing Spondylitis Functional Index; CHAQ, Childhood Health Assessment Questionnaire; KINDL, Questionnaire for Measuring Health-Related Quality of Life in children and adolescents; n.d., not done; NRS, numerical rating scale.