Page 112 - The clinical aspects and management of chronic migraine Judith Anne Pijpers

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Chapter 6
score of at least eight on the subscales of the Hospital Anxiety and Depression scale (HADS-A and HADS-D) 19.
Primary outcome was reversion from chronic to episodic migraine (i.e. headache no longer fulfils criteria of chronic migraine) from baseline to the last 4 weeks of the treatment period (weeks 9-12). Secondary outcomes were i) ≥ 50% response in migraine days, i.e. reduction in monthly migraine days (MMD) of 50% or more; ii) reduction in number of monthly migraine days (MMD); iii) reduction in number of monthly headache days (MHD). A migraine day was defined as a day fulfilling criteria for migraine with or without aura, or treated with migraine specific acute medication 2. A headache days was defined as a day with migraine or non-migraine headache of any duration.
Data analysis and statistics
Descriptives are reported as means ± standard deviations or numbers with proportions, and differences between groups were tested with independent sample t-tests and χ2 tests.
Multivariate regression models were used to test the association between presence of (subtypes of) cutaneous allodynia and reversion from chronic to episodic migraine (primary endpoint), a 50% or greater reduction in migraine days, reduction in number of MMD and reduction in number of MHD (secondary endpoints). Gender, age, depression and anxiety were included in the model. Medication intake and migraine or headache days at baseline were added to the model in separate supplementary analyses, since these factors are likely related to cutaneous allodynia and the outcomes, but the magnitude and direction of these influences are not yet established. Treatment with botulinum toxin A or placebo was not included in the models, as this factor was extensively tested previously, and botulinum toxin A did not significantly improve any of the outcome measures 17.
Primary analysis included all patients providing baseline data (n=173). Missing data on migraine days or headache days during follow-up, defined as less than 14 completed days on a headache diary, were handled using multiple imputation. In case of 14-27 completed days, the existing data were extrapolated to a 28 days period. In all analyses, two-sided p values <0.05 were considered statistically significant. Analyses were performed in SPSS Statistics 23.0 (SPSS Inc., ICM, USA).