Ineffective acute treatment of episodic migraine is associated with new-onset chronic migraine

OBJECTIVE:To test the hypothesis that ineffective acute treatment of episodic migraine (EM) is associated with an increased risk for the subsequent onset of chronic migraine (CM). METHODS:In the American Migraine Prevalence and Prevention Study, respondents with EM in 2006 who completed the Migraine Treatment Optimization Questionnaire (mTOQ-4) and provided outcome data in 2007 were eligible for analyses. The mTOQ-4 is a validated questionnaire that assesses treatment efficacy based on 4 aspects of response to acute treatment. Total mTOQ-4 scores were used to define categories of acute treatment responsevery poor, poor, moderate, and maximum treatment efficacy. Logistic regression models were used to examine the dichotomous outcome of transition from EM in 2006 to CM in 2007 as a function of mTOQ-4 category, adjusting for covariates. RESULTS:Among 5,681 eligible study respondents with EM in 2006, 3.1% progressed to CM in 2007. Only 1.9% of the group with maximum treatment efficacy developed CM. Rates of new-onset CM increased in the moderate treatment efficacy (2.7%), poor treatment efficacy (4.4%), and very poor treatment efficacy (6.8%) groups. In the fully adjusted model, the very poor treatment efficacy group had a more than 2-fold increased risk of new-onset CM (odds ratio = 2.55, 95% confidence interval 1.42–4.61) compared to the maximum treatment efficacy group. CONCLUSION:Inadequate acute treatment efficacy was associated with an increased risk of new-onset CM over the course of 1 year. Improving acute treatment outcomes might prevent new-onset CM, although reverse causality cannot be excluded.