Table 3.
Test–retest reliability results for each core item/domain and the composite index score (COMI index score)
| Domain/core items (n) | Range | Mean (SD) first test | Mean (SD) re-test | SEM | MDC | MDC (%) | ICC (95 % CI) | Kappa W (95 % CI) |
|---|---|---|---|---|---|---|---|---|
| Pain symptoms (61) | 0–10 (highest)a | 5.41 (2.15) | 5.48 (2.18) | 1.12 | 3.11 | 31.1 | 0.85 (0.74–0.91) | NA |
| Back function (61) | 1–5 | 3.38 (0.90) | 3.15 (1.0) | 0.52 | 1.45 | 29.0 | 0.81 (0.67–0.89) | 0.68 (0.53–0.08) |
| Symptom-specific well-being (61) | 1–5 | 4.11 (1.07) | 4.07 (1.14) | 0.77 | 2.13 | 42.6 | 0.68 (0.47–0.81) | 0.51 (0.26–0.77) |
| General well-being (61) | 1–5 | 2.90 (0.75) | 2.79 (0.91) | 0.52 | 1.43 | 28.6 | 0.76 (0.60–0.86) | 0.61 (0.45–0.77) |
| Disability (59) | 1–5 (mean)b | 2.76 (1.20) | 2.62 (1.22) | 0.57 | 1.56 | 31.2 | 0.88 (0.79–0.93) | NA |
| COMI index score (59) | 0–10 | 5.66 (1.76) | 5.39 (1.92) | 0.80 | 2.21 | 22.1 | 0.89 (0.82–0.94) | NA |
SEMagreement √ within people residual mean square, MDCindividual (√ within people residual mean square) × 2.77, ICCagreement two-way random effects model (absolute agreement)
MDC % MDC as percentage of maximum score, Kappa W weighted kappa with quadratic weighting, CI confidence interval, NA not assessed
aHighest pain of back/leg pain
bMean of social/work disability