SynthesisThe journal of headache and pain2026
Is migraine a spectrum disorder? Questioning the concept of "episodic" and "chronic" migraine using population-based data from 10,226 adults with migraine from 14 countries.
Synthesis in The journal of headache and pain, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
0 citing papers in PubMed.
No citing paper in PubMed yet.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
2 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThe first edition of the International Classification of Headache Disorders (ICHD-I) did not recognize chronic migraine (CM). ICHD-II introduced CM as a complication of migraine, with criteria that were widely criticized and later revised to require ≥ 15 monthly headache days (MHDs) with ≥ 8 monthly migraine days (MMDs). ICHD-3 reclassified CM as a type distinct from episodic migraine, retaining these frequency thresholds but without empirical justification. We investigated whether population-based evidence on headache characteristics and burden supported distinction between episodic and chronic migraine types, or indicated that migraine was better conceptualized as a single disorder expressed along a frequency spectrum.
methodsWe performed a meta-analysis of individual participant data from 15 cross-sectional population-based surveys from the Global Campaign against Headache, all randomly selecting adults (18-65 years) and using the HARDSHIP questionnaire for data collection. Diagnoses made algorithmically observed the hierarchical order of ICHD. We identified four migraine groups: (1) migraine (definite+probable) including, and (2) migraine (definite+probable) excluding those with concomitant probable medication-overuse headache (pMOH); (3) migraine (definite only) including, and (4) migraine (definite only) excluding those with concomitant pMOH. MMDs and MHDs were regressed against headache characteristics, quality of life (QoL) and impaired participation.
resultsAmong 36,407 participants (mean age 37.5 years; 53.4% females), 10,266 (28.2%) met criteria for migraine (14.6% definite; 13.6% probable), including 896 (2.5%) with concomitant pMOH. Distributions of MMDs and MHDs were heavily right-skewed, peaking at 3 days/month, but showed no inflections at the thresholds for CM. Age was positively associated with headache frequency, while most headache characteristics varied minimally across frequencies. QoL declined slightly but linearly with increasing frequency, whereas lost workdays, household days and social days increased more-or-less linearly (albeit that household days plateaued after 15 days/3 months). Regressions were strikingly similar across genders and the four migraine groups.
conclusionPopulation-based evidence indicates that migraine, considered in relation to headache frequency, characteristics and attributed burden, is better understood as a spectrum disorder rather than as two (or more) entities distinguished categorically by frequency. The current thresholds for CM do not align with detectable step-increments in headache characteristics or burden. These findings fill a major knowledge gap, usefully informing the development of ICHD-4.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.