Page 72 - The clinical aspects and management of chronic migraine Judith Anne Pijpers
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Chapter 4
secondary outcomes were change from baseline in number of (i) headache days; (ii) migraine days (days with headache fulfilling migraine criteria or treated with acute migraine medication); (iii) moderate or severe headache days; (iv) hours with headache (cumulative); and (v) days with use of acute headache medication. We also assessed: (i) proportion of participants with ≥ 50% or ≥ 25% reduction in headache days; (ii) proportion of participants who persevered successfully with medication withdrawal (≤ 2 medication days per 4 weeks); (iii) proportion of participants without medication overuse (< 10 medication days per 4 weeks); and (iv) HIT-6 and MIDAS scores.
To assess satisfaction, participants were asked after 12 weeks to rate their treatment on a 0-10 satisfactory scale (0=completely dissatisfied, 10 = completely satisfied), and whether they would recommended their therapy to family or friends (‘no’, ‘yes’ or ‘I don’t know’). To assess success of blinding, we asked participants and investigators three days and 12 weeks after therapy onset which treatment they believed they had received or given (BTA, placebo, or don’t know).
Statistical analysis
We defined a 20-percentage point difference in mean percentage change in 4-weekly headache days from baseline to weeks 9-12 of BTA versus placebo, as clinically meaningful. Based on a previous withdrawal study,6 we expected a standard deviation of 40 percentage points. Thus, 84 participants per group were required to detect a 20-percentage point difference with 90% power and a 0.05 type 1 error. To allow for dropouts, we aimed to include 90 participants per group.
The primary intention-to-treat analysis included all patients. We used a pre- specified analysis of covariance (ANCOVA) model to compare the percentage change in 4-weekly headache days between the two groups. Fixed factors were treatment, support by a headache nurse, gender, depression and anxiety. Covariates were age and number of baseline headache days. Similar models were used for the secondary outcomes after 12 weeks. Missing data on follow-up (< 14 completed headache dairy days) was handled using multiple imputation. Ten imputed datasets on headache days, migraine days, moderate or severe headache days, headache duration, and SF-36 score were generated using




























































































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