The burden of high-frequency episodic migraine and chronic migraine in the population-based PopHEAD study

AimThe diagnostic criteria for chronic migraine, which are based on the total number of monthly headache days, are the subject of ongoing debate. The present study aimed to investigate and compare the burden of disease and quality of life between high-frequency episodic migraine and chronic migraine, using data from the large population-based PopHEAD study.MethodsPopHEAD is a population-based cross-sectional study in the Norwegian county of Vestfold and Telemark performed in 2023. Among 28,753 randomly selected adults (aged 18-70 years) invited to complete an electronic questionnaire, 8265 (28.7%) participants responded. The questionnaire was a modified version of the Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation questionnaire, and migraine was classified using a diagnostic algorithm that has been validated by telephone interview in this population. High-frequency episodic migraine was classified according to newly proposed criteria, and chronic migraine according to International Classification of Headache Disorders, 3rd edition (ICHD-3) criteria. Using linear regression for continuous variables and logistic regression for binary outcomes, we compared the disease burden and quality of life between participants classified with high-frequency episodic migraine and those with chronic migraine. The analysis was conducted in two steps: a primary analysis adjusted for age and sex, as well as a second analysis with an additional adjustment for monthly migraine days.ResultsOf the 8265 responders, 225 had high-frequency episodic migraine and 349 had chronic migraine. Compared to the high-frequency episodic migraine group, the chronic migraine group had more monthly migraine days (17.9 vs. 9.7, p < 0.001) and headache days (20.8 vs. 9.9, p < 0.001). The chronic migraine group also used more acute medication (p < 0.001). In analyses adjusted for age and sex, participants with chronic migraine reported greater disease burden across almost all measures, including work and social impairment, and had a lower quality of life (p < 0.01). With additional adjustment for monthly migraine days, no significant differences in disease burden were found between the two groups, except from days missed from household work (p = 0.03).ConclusionsThe higher disease burden observed in chronic migraine compared to high-frequency episodic migraine was fully explained by the higher number of monthly migraine days in the chronic migraine group. Our findings support previous suggestions to simplify the ICHD-3 criteria for chronic migraine by basing it solely on the number of monthly migraine days.