Primary outcomes analysed by linear regression
| Outcome | ICC (%) | Crude | Adjusted* | ||
|---|---|---|---|---|---|
| Coeff (95% CI) | p Value | Coeff (95% CI) | p Value | ||
| Headache days/month | 22.3 | −7.2 (−11.2 to −3.1) | <0.001 | −7.3 (−11.3 to −3.2) | <0.001 |
| Medication days/month | 10.6 | −8.4 (−13.4 to −3.4) | 0.002 | −7.9 (−12.5 to −3.2) | 0.001 |
| Change in headache days/month | 26.1 | −6.7 (−9.6 to −3.9) | <0.001 | −6.8 (−9.6 to −3.7) | <0.001 |
| Change in medication days/month | 10.4 | −9.8 (−13.1 to −6.6) | <0.001 | −9.5 (−12.8 to −6.2) | <0.001 |
Coeff, regression coefficient in linear mixed model, showing average difference (number of days) between business as usual (coded as 0) and brief intervention (coded as 1) groups; ICC, intraclass correlation coefficient.
*Regression coefficients adjusted for age, gender and co-occurrence of migraine.