Statistical Analysis
Headache, anxiety, headache, migraine, depression, type headache
MIGRAINE, EVENTS, SECONDARY, ADVERSE EVENTS
Our analyses followed the prespecified statistical analysis plan available in the Supplement (For primary and secondary analyses, treatment effects were estimated using linear mixed-effects models with partial clustering to account for clustering in the self-management arm. Analyses were adjusted for age, gender, and the baseline value stratification factors. Adjusted treatment effect estimates and associated 95% CI are presented for all analyses. All statistical tests were 2-sided at the 5% significance level. As per analysis plan, if the proportion of people with chronic tension–type headache only was <15%, main analyses would be on the population with chronic migraine or chronic tension–type headache and episodic migraine.Drug use data for migraine (except Botox and calcitonin gene–related peptide monoclonal antibodies) reported in participant questionnaires were converted to amounts taken over the previous 28 days and then converted to defined daily doses (DDD).We predefined minimal adherence to the intervention as the participant attending day 1 of the intervention plus the one-to-one session with the nurse and full adherence as the participant attending the entire intervention. We performed complier averaged causal effect (CACE) analyses for both levels of adherence for the primary outcome only to estimate the difference between observed compliers (intervention) and potential compliers (control).We performed prespecified subgroup analyses to examine whether baseline anxiety (HADS anxiety subscale scores ≥11), depression (HADS depression subscale ≥11), and severity (HIT-6 ≤64 and >64) moderated treatment effect for primary outcome only.Headache days, headache duration, and severity were reported by participants at multiple time points. To account for the within-subject dependency, each outcome was analyzed using a mixed-effects model to estimate the treatment effect over time with random effects at the participant level. The models were adjusted for the same variables as in the primary analyses (fixed effects).We presented the primary outcome separately for the following: whole population, those with chronic migraine, or those with chronic tension–type headache and episodic migraine, and those with or without medication overuse. The small number with only chronic tension–type headache precluded presenting data on these individuals separately.We performed 2 sensitivity analyses: (1) excluding participants who were included in the process evaluation interviews andAdverse events (AEs) and serious adverse events (SAEs) were summarized as frequencies and percentages (%). If possible, the 2 arms were compared using either the χWe performed a prospective within-trial economic evaluation from the perspective of the UK National Health Service and Personal Social Services.