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 response: very 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.