Table 3.
Variables associated with total ASES score across time, based on multivariate linear mixed models
| Variable | Coefficient (95% CI) | p-value⊥ | Conditional R2 | Interactions |
|---|---|---|---|---|
| DAS28-CRP | −0.22 (−0.32, −0.11) | <0.001 | 0.614 | HAQ* |
| HAQ | −1.06 (−1.27, −0.84) | <0.001 | 0.610 | - |
| Pain (VAS) | −0.14 (−0.19, −0.09) | <0.001 | 0.603 | - |
| Fatigue (VAS) | −0.15 (−0.19, −0.10) | <0.001 | 0.606 | - |
| PGA (VAS) | −0.16 (−0.21, −0.11) | <0.001 | 0.594 | - |
| SF-36 MCS | 0.40 (0.29, 0.50) | <0.001 | 0.607 | - |
| IPQ-R illness coherence | 0.12 (0.09, 0.15) | <0.001 | 0.617 | - |
| IPQ-R treatment control | 0.16 (0.12, 0.20) | <0.001 | 0.619 | - |
| IPQ-R personal control | 0.09 (0.06, 0.11) | <0.001 | 0.608 | - |
| IPQ-R consequences | −0.17 (−0.19, −0.15) | <0.001 | 0.690 | - |
| IPQ-R emotional representations | −0.11 (−0.12, −0.09) | <0.001 | 0.634 | - |
| RAQoL | −0.11 (−0.12, −0.09) | <0.001 | 0.640 | HAQ** |
| PhGA (VAS) | −0.12 (−0.19, −0.04) | 0.002 | 0.613 | - |
| TJC28 | −0.01 (−0.06, 0.03) | 0.590 | 0.594 | - |
| SJC28 | 0.01 (−0.04, 0.07) | 0.630 | 0.594 | - |
| CRP | 0.00 (−0.01, 0.01) | 0.550 | 0.594 | - |
| ESR | 0.00 (0.00, 0.01) | 0.320 | 0.597 | - |
⊥Bonferroni correction for multiple comparisons was applied, setting the significance level at p < 0.003
*Interaction (ß = 0.24; 95% CI = 0.12–0.36; p < 0.001) implies that the additional effect of DAS28-CRP on self-efficacy (SE) decreases with increasing HAQ
**Interaction (ß = 0.05; 95% CI = 0.03–0.08; p < 0.001) implies that the additional effect of RAQoL on SE decreases with increasing HAQ
ASES Arthritis Self-Efficacy Scale, DAS28 Disease Activity Score in 28 joints, HAQ Health Assessment Questionnaire, VAS visual analogue scale, PGA patient’s global assessment of disease activity, SF-36 MCS Short-Form 36 mental component score, IPQ-R Revised Illness Perception Questionnaire, PhGA physician’s global assessment of disease activity, TJC28 tender joint count in 28 joints, SJC28 swollen joint count in 28 joints, CRP C-reactive protein, ESR erythrocyte sedimentation rate