Two of the authors (SP and MP) screened titles and
abstracts for relevance using predefined inclusion and
exclusion criteria. Studies were included if they reported
the development or application of quality indicators for
headache care or evaluated other aspects of service provision
for headache disorders. Articles unrelated to primary
headache disorders, review articles, drug treatment studies,
case reports, letters and comments, and papers that were
not written in English were excluded. We obtained full-text
versions of papers selected for further review, and again
evaluated these against our inclusion and exclusion criteria.
Any disagreements were resolved by consensus. Figure 1
shows the flow of studies through the review.