What do we already know about this topic?

• The International Classification of Headache Disorders, 3^rd edition (ICHD-3), defines chronic migraine as 15 or more monthly headache days for ≥3 months with criteria for migraine, with or without aura, met on ≥8 days per month.¹
• Episodic migraine is migraine with fewer than 15 monthly headache days.
• Differences in the burden of migraine among people with various headache frequencies have not been well characterized.

How was this study conducted?

• The CaMEO Study was a longitudinal, web-based study of adults (aged 26–57 years) meeting modified ICHD-3 migraine criteria (N=16,789).²
• Data was subgrouped based upon self-reported monthly headache days: Low-and moderate-frequency episodic migraine (LFEM), HFEM, LFCM, and high-frequency chronic migraine (HFCM).
• The relationships of monthly headache day category with various outcome measures, such as headache-related disability, characteristics and medication, were assessed by chi-test for trend.