Summary of the primary and secondary outcomes across follow-up points*
| Outcome | Time point (months) | Analysis method (effect size) | Adjusted† effect size (95% CI) | P value | Unadjusted effect size (95% CI) | P value | |
| Primary outcome | |||||||
| CWP CWP (per protocol) CWP (with multiple imputation) | 3 | Logistic regression (OR) | 1.08 (0.74 to 1.58) | 0.691 | 1.07 (0.75 to 1.53) | 0.716 | |
| 1.15 (0.75 to 1.75) | 0.519 | 1.18 (0.77 to 1.66) | 0.522 | ||||
| 1.06 (0.74 to 1.54) | 0.749 | 1.05 (0.72 to 1.53) | 0.816 | ||||
| CWP‡ CWP (per protocol) CWP (with multiple imputation) | 12 | 1.05 (0.75 to 1.48) | 0.771 | 1.04 (0.72 to 1.48) | 0.849 | ||
| 1.11 (0.81 to 1.50) | 0.519 | 1.09 (0.74 to 1.60) | 0.673 | ||||
| 1.04 (0.75 to 1.45) | 0.982 | 1.03 (0.74 to 1.42) | 0.964 | ||||
| CWP CWP (per protocol) CWP (with multiple imputation) | 24 | 0.85 (0.68 to 1.07) | 0.163 | 0.84 (0.61 to 1.18) | 0.317 | ||
| 0.85 (0.64 to 1.12) | 0.241 | 0.84 (0.58 to 1.20) | 0.330 | ||||
| 0.85 (0.66 to 1.09) | 0.220 | 0.84 (0.65 to 1.09) | 0.196 | ||||
| CWP | 3, 12, 24 | GEE (OR) | 1.00 (0.96 to 1.04) | 0.923 | 1.00 (0.96 to 1.04) | 0.835 | |
| Secondary outcomes | |||||||
| Global impression of change§ | 3 | Ordinal logistic regression (OR) | 0.42 (0.32 to 0.55) | <0.001 | 0.43 (0.34 to 0.56) | <0.001 | |
| 12 | 0.51 (0.39 to 0.67) | <0.001 | 0.53 (0.41 to 0.68) | <0.001 | |||
| 24 | 0.55 (0.43 to 0.70) | <0.001 | 0.58 (0.45 to 0.73) | <0.001 | |||
| CWP risk profile | Somatic symptoms score | 3 | Ordinal logistic regression (OR) | 0.79 (0.60 to 1.03) | 0.084 | 0.83 (0.64 to 1.08) | 0.173 |
| 12 | 0.86 (0.71 to 1.04) | 0.112 | 0.85 (0.65 to 1.11) | 0.237 | |||
| 24 | 0.81 (0.59 to 1.12) | 0.206 | 0.90 (0.67 to 1.21) | 0.498 | |||
| Illness behaviour score | 3 | Linear regression (mean difference) | −0.17 (−0.58 to 0.24) | 0.385 | −0.25 (−0.79 to 0.29) | 0.360 | |
| 12 | −0.81 (−1.54 to −0.09) | 0.030 | −0.74 (−1.32 to −0.17) | 0.011 | |||
| 24 | −1.25 (−2.15 to −0.35) | 0.010 | −1.20 (−1.83 to −0.58) | <0.001 | |||
| Sleep problems score | 3 | Linear regression (mean difference) | −0.62 (−1.26 to 0.02) | 0.057 | −0.62 (−1.31 to 0.08) | 0.081 | |
| 12 | −0.95 (−1.48 to −0.42) | 0.002 | −1.00 (−1.70 to −0.30) | 0.005 | |||
| 24 | −0.51 (−1.25 to 0.23) | 0.161 | −0.52 (−1.39 to 0.16) | 0.117 | |||
| Psychological distress (GHQ) | 3 | Ordinal logistic regression (OR) | 0.55 (0.43 to 0.69) | <0.001 | 0.58 (0.45 to 0.76) | <0.001 | |
| 12 | 0.65 (0.50 to 0.86) | 0.002 | 0.70 (0.54 to 0.90) | 0.007 | |||
| 24 | 0.76 (0.60 to 0.96) | 0.024 | 0.74 (0.56 to 0.98) | 0.037 | |||
| Chalder Fatigue Score | 3 | Linear regression (mean difference) | −1.36 (−2.10 to −0.64) | 0.001 | −1.40 (−1.97 to −0.82) | <0.001 | |
| 12 | −1.02 (−1.63 to −0.42) | 0.003 | −1.03 (−1.64 to −0.42) | 0.001 | |||
| 24 | −0.93 (−1.62 to −0.23) | 0.012 | −0.93 (−1.58 to −0.27) | 0.006 | |||
| Quality of Life (EQ-5D-5L utility score) | 3 | Linear regression (mean difference) | 0.009 (−0.009 to 0.028) | 0.304 | 0.021 (−0.004 to 0.046) | 0.101 | |
| 12 | 0.024 (0.009 to 0.040) | 0.004 | 0.037 (0.010 to 0.064) | 0.007 | |||
| 24 | 0.030 (0.009 to 0.050) | 0.008 | 0.040 (0.011 to 0.069) | 0.007 | |||
| ICECAP-A tariff | 3 | Ordinal logistic regression (OR) | 1.14 (0.89 to 1.48) | 0.304 | 1.17 (0.86 to 1.59) | 0.323 | |
| 12 | 1.39 (0.94 to 2.04) | 0.096 | 1.39 (1.01 to 1.91) | 0.042 | |||
| 24 | 0.88 (0.67 to 1.15) | 0.338 | 0.99 (0.70 to 1.41) | 0.966 | |||
| Fibromyalgia criteria | Widespread Pain Index | 3 | Poisson regression (IRR) | 0.98 (0.90 to 1.07) | 0.698 | 1.01 (0.93 to 1.10) | 0.771 |
| 12 | 0.88 (0.80 to 0.98) | 0.018 | 0.92 (0.84 to 0.99) | 0.036 | |||
| 24 | 0.88 (0.78 to 0.98) | 0.022 | 0.92 (0.84 to 1.00) | 0.058 | |||
| Symptom Severity Scale | 3 | Linear regression (mean difference) | −0.28 (−0.52 to −0.04) | 0.026 | −0.25 (−0.57 to 0.65) | 0.118 | |
| 12 | −0.52 (−0.75 to −0.28) | <0.001 | −0.59 (−0.91 to −0.27) | <0.001 | |||
| 24 | −0.29 (−0.55 to −0.02) | 0.040 | −0.28 (−0.61 to 0.05) | 0.100 | |||
*Analyses shaded in grey favour tCBT over usual care at prespecified significance level for secondary outcomes (p<0.01). Except for EQ-5D-5L, mean differences less than 0 and ORs less than 1 favour the treatment group.
†Adjusted analyses control for the number of risk factors (two or three), age, gender, baseline score (if applicable) and centre (random effect). Analyses are intention to treat unless otherwise stated.
‡Primary outcome.
§OR of 1 point increase in global impression of change score (worsening of health).
CWP, chronic widespread pain; EQ5D-5D-5L, EuroQol Questionnaire-five dimensions-five levels; GEE, generalised estimating equations; GHQ, General Health Questionnaire; ICECAP-A, ICEpop CAPability measure for Adults; IRR, incidence rate ratio; ;tCBT, telephone-delivered cognitive–behavioural therapy.