Table 6.

Adaptability of the model according to local requirements and resources (adapted from [29])

Requirement	Adaptation
Doctors vs other health-care providers (HCPs)	Many countries, as policy, are expanding the health-care roles of HCPs other than doctors. Systems in some countries may depend on service provision at level 1, and perhaps level 2, by clinical officers, nurses and/or community health workers. This is the way forward, supported by training, if the alternative is nothing.
Primary vs secondary care	Level 1 is in primary care. Level 2, on the other hand, can be in primary or secondary care: common options include neurologists or physicians (trained but non-specialist) in community or district hospitals or polyclinics.
2-level systems	Level-3 centres are in secondary care (or tertiary care in countries that make this distinction). Level 3 is therefore costly and may be unaffordable. When it cannot be fully implemented within this model, or at all, this does not detract from the benefits that can be provided to the great majority by levels 1 and 2.
Combined levels	Level 1 is by its nature community based. It is possible nonetheless, and may be appropriate, for certain level-2 centres also to offer local level-1 care. Similarly, there is no intrinsic reason why one centre cannot provide both level-2 and level-3 care.
Division of caseload	The 90:9:1% split between levels 1, 2 and 3 are estimates of need based largely on expert opinion. Throughout the world, there are variations in prevalence and characteristics of the common headache disorders, particularly in the frequency of medication-overuse headache [53]. The division of caseload between levels and capacity at each level may need adjustment, ideally based on locally gathered empirical data. The model will accommodate this without fundamental change.
Integration within existing services	The model adapts equally comfortably to layered and to hub-and-spoke structures, or hybrids of these, according to a country’s broader health-service structure. It permits bottom-up organization (patient flows driven upwards by demand at lower levels) or top-down (flows induced upwards by available capacity at higher levels) (Fig. 3).