In this nationwide survey of people with headache in Denmark, we identified a low uptake of care despite a perceived need for care. These findings were in parallel with evidence both of suboptimal medical care and of poor awareness of headache among those affected by it, and despite that the HINDER panel was biased towards those more likely to be interested in, to be concerned about and to consult for headache. Evidence of this bias was provided by the gender divide, which was not as the general population, by the high proportion of participants with greater headache-attributed burden, by diagnoses not in accordance with expected proportions, and by the relatively large proportions treated in secondary and tertiary care. For these reasons, our findings of suboptimal care and poor awareness are likely to be amplified among the general population in Denmark.

The essential finding – that one quarter of participants had not sought headache services despite more than two thirds of these same people reporting headache as an everyday burden – is in line with those of a previous Danish survey [11]. As headache services are widely available in Denmark, these findings contribute to a growing body of evidence demonstrating that it is insufficient merely to make services or treatments available [15, 16]. Other countries in Europe, and the United States, have also reported low healthcare utilization, with lesser disease burden similarly associated with lower utilization, and rates far from 100% even among those with highest burden [11, 13, 14].

The reasons for not seeking care that should be beneficial are certainly multiple, high among them being lack of awareness and apparently suboptimal care. More than one third of those not seeking headache care reported not knowing whether their general practitioner would be able to help them, and, more worrying, of those who had sought care, most did not feel it better equipped them to manage their headache attacks. The relatively frequent use of complementary and alternative therapies reflected this. Inadequacy of care is not merely perceived: it is substantiated by our findings of opioid usage, contrary to international and national guidelines, and of low utilization (and ignorance among those with migraine) of triptans. Low adherence to triptan usage was also identified in the Danish Migraine Population Cohort study [17]. In other countries, diagnostic delays, misdiagnosis and otherwise suboptimal management all negatively impact the quality of clinical care [3], consequences of educational gaps occurring first in medical schools and subsequently in residency programmes, themselves due to a paradoxical lack of priority accorded to headache [5, 18]. Despite being relatively well organized, highly resourced and readily accessible [10], Danish headache services are unlikely to be, and evidently are not, entirely free of these deficiencies contributing to lowered expectations and discouraging utilization of headache services.

There are almost certainly other deterrents to care-seeking. Trivialization of headache disorders has been widely reported, and sometimes stigmatization of those who report it. Evidence of these lies in the reports of high rates of work-presenteeism, coupled with lack of support from employers and others [11, 16, 19,20,21,22,23].

The sampling method imposed biases. Not all adults in Denmark are Facebook users, and the recruitment campaign would not have had equal exposure to all, with older adults (above middle age) more likely to be excluded. Interest bias was certain to have influenced willingness to participate, favouring those worst affected. These biases, however, most probably led to conservative findings and underestimates. We could not relate our findings to detailed demographic characteristics, social factors such as financial situation and educational level, or medical histories, since we did not enquire into these. Furthermore, we recognize that self-reported headache diagnoses are of questionable reliability. However, the essential point is that people with headache appear disinclined to seek readily available healthcare despite, therefore, not being reliably informed of what their headache might be. Our categorization of headache frequency into once or more per week, month or year was considered a necessary simplification, but it limited quantitative estimation of disease burden.