Olesen, Jes

Abstract Objective To evaluate whether the 15‐day threshold of headache days per month adequately reflects substantial differences in disability across the full spectrum of migraine. Background The monthly frequency of headache days defines migraine subtypes and has crucial implications for epidemiological and clinical research as well as access to care. Methods The patients with migraine ( N = 836) who participated in the American Registry for Migraine Research, which is a multicenter, longitudinal patient registry, between February 2016 and March 2020, were divided into four groups based on monthly headache frequency: Group 1 (0–7 headache days/month, n = 286), Group 2 (8–14 headache days/month, n = 180), Group 3 (15–23 headache days/month, n = 153), Group 4 (≥24 headache days/month, n = 217). Disability (MIDAS), Pain intensity (NRS), Work Productivity and Activity Impairment (WPAI), Pain Interference (PROMIS‐PI), Patient Health Questionnaire‐4 (PHQ‐4), and General Anxiety Disorder‐7 (GAD‐7) scores were compared. Results Mean (standard deviation [SD]) age was 46 (13) years (87.9% [735/836] female). The proportion of patients in each group was as follows: Group 1 (34.2% [286/836]), Group 2 (21.5% [180/836]), Group 3 (18.3% [153/836]), and Group 4 (26.0% [217/836]). There were significant relationships with increasing disability, lost productive time, and pain interference in higher headache frequency categories. There were no significant differences between Group 2 and Group 3 for most measures (NRS, all WPAI scores, PROMIS‐PI, GAD‐7, and PHQ‐4), although MIDAS scores differed (median [interquartile range (IQR)]; 38 [20–58] vs. 55 [30–90], p < 0.001). Patients in Group 1 had significantly lower MIDAS (median [IQR];16 [7–30], p < 0.001), WPAI‐% total active impairment (mean (SD): Group 1 [30.9 (26.8)] vs. Group 2 [39.2 (24.5), p = 0.017], vs. Group 3 [45.9 (24.1), p < 0.001], vs. Group 4 [55.3 (23.0), p < 0.001], and PROMIS‐PI‐T score (Group 1 [60.3 (7.3)] vs. Group 2 [62.6 (6.4), p = 0.008], vs. Group 3 [64.6 (5.6), p < 0.001], vs. Group 4 [66.8 (5.9), p < 0.001]) compared to all other groups. Patients in Group 4 had significantly higher MIDAS (median (IQR): Group 4 [90 (52–138)] vs. Group 1 [16 (7–30), p < 0.001], vs. Group 2 [38 (20–58), p < 0.001], vs. Group 3 [55 (30–90), p < 0.001], WPAI‐%Presenteeism (Group 4 [50.4 (24.4)] vs. Group 1 [28.8 (24.9), p < 0.001], vs. Group 2 [34.9 (22.3), p < 0.001], vs. Group 3 [40.9 (22.3), p = 0.048], WPAI‐% total work productivity impairment (Group 4 [55.9 (26.1)] vs. Group 1 [32.1 (37.6), p < 0.001], vs. Group 2 [38.3 (24.0), p < 0.001], vs. Group 3 [44.6 (24.4), p = 0.019]), and WPAI‐%Total activity impairment (Group 4 [55.3 (23.0)] vs. Group 1 [30.9 (26.8), p < 0.001], vs. Group 2 [39.2 (24.5), p < 0.001], vs. Group 3 [45.9 (24.1), p = 0.025]) scores compared with all other groups. Conclusion Our data suggest that the use of a 15 headache day/month threshold to distinguish episodic and chronic migraine does not capture the burden of illness nor reflect the treatment needs of patients. These results have important implications for future refinements in the classification of migraine.

Introduction ICHD-3 criteria for chronic migraine (CM) include a mixture of migraine and tension-type-like headaches and do not account for patients who have a high frequency of migraine but no other headaches. Materials and methods Patients from the Danish Headache Center and their relatives with ICHD-3 defined CM were compared with patients with high frequency episodic migraine (HFEM). Danish registries were used to compare the socioeconomic impact in these two groups. A Russian student population was used to determine the generalizability of the number of patients fulfilling CM and the proposed diagnostic criteria for CM. Results There was no difference in the demographic profile between the two groups in the Danish cohort. The number of lifelong or annual attacks ( p > 0.3), comorbid diseases, or self-reported effect of triptans ( p = 1) did not differ. HFEM patients purchased more triptans than CM patients ( p = 0.01). CM patients received more early pension ( p = 0.00135) but did not differ from HFEM patients with regard to sickness benefit ( p = 0.207), cash assistance ( p = 0.139), or rehabilitation benefit ( p = 1). Discussion Patients with HFEM are comparable to CM patients with regard to chronicity and disability. We therefore suggest classifying CM as ≥ 8 migraine days per month (proposed CM), disregarding the need for ≥ 15 headache days per month. The proposed diagnostic criteria for CM approximately doubled the number of patients with CM in both the Danish and the Russian materials. Extending the definition of CM to include patients with HFEM will ensure that patients with significant disease burden and unmet treatment needs are identified and provided appropriate access to the range of treatment options and resources available to those with CM. Conclusion Patients with migraine on eight or more days but not 15 days with headache a month are as disabled as patients with ICHD-3 defined CM. They should be included in revised diagnostic criteria for chronic migraine.