Green flags and headache: a concept study using the Delphi method

Heiko Pohl, Thien Phu Do, David Garcia-Azorin, Jakob Møller Hansen, Espen Saxhaug Kristoffersen, Sarah E Nelson, Mark Obermann, Peter Sandor, Christoph Schankin, Henrik Winther Schytz, Alex Sinclair, Guus G Schoonman, Andreas R Gantenbein

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


The aim of this study was to collect and rate Green Flags, that is, symptoms or pieces of information indicating that a patient is more likely to suffer from a primary than from a secondary headache.

When assessing headaches, a central question to be answered is whether the pain is primary or secondary to another disorder. To maximize the likelihood of a correct diagnosis, relevant signs and symptoms must be sought, identified, and weighed against each other.

The project was designed as a Delphi study. In the first round, an expert panel proposed green flags that were rated anonymously in two subsequent rounds. Proposals with an average rating of 4.0 and higher on a scale from 0 to 5 reached consensus.

Five Green Flags reached consensus: (i) “The current headache has already been present during childhood”; (ii) “The headache occurs in temporal relationship with the menstrual cycle”; (iii) “The patient has headache‐free days“; (iv) “Close family members have the same headache phenotype”; and (v) “Headache occurred or stopped more than one week ago.”

We propose five Green Flags for primary headache disorders. None being a pathognomonic sign, we recommend searching for both Green Flags and Red Flags. If both are present, a secondary headache should be suspected. Overall, the application of the Green Flag concept in clinical practice is likely to increase diagnostic accuracy and improve diagnostic resource allocation. Prospective studies in clinical populations should be conducted to validate these Green Flags.
Original languageEnglish
Pages (from-to)1-10
Number of pages10
Issue number00
Early online date6 Jan 2021
Publication statusE-pub ahead of print - 6 Jan 2021

Bibliographical note

Funding Information:
Heiko Pohl was funded by the Werner Dessauer Stiftung and received speaker fees from TEVA Pharmaceuticals and honoraria from Eli Lilly. Thien Phu Do reports no conflicts of interest. David García‐Azorín reports no conflict of interest. Jakob Møller Hansen reports no conflicts of interest. Espen Saxhaug Kristoffersen reports no conflicts of interest. Sarah E. Nelson reports receiving compensation from Springer Healthcare and a grant from the Brain Aneurysm Foundation. Mark Obermann received scientific support, travel support, and/or honoraria from Biogen Idec, Novartis, Sanofi/Genzyme, Pfizer, Teva, Lilly, Schwarz, and Heel. He received research grants from Allergan, Electrocore, Heel, and the German Ministry for Education and Research (BMBF). Peter S. Sandor received financial support from the Research Fund of the RehaClinic group. Christoph J. Schankin received scientific support, travel support, and/or honoraria from Novartis, Eli Lilly, TEVA Pharmaceuticals, Allergan, Almirall, Amgen, MindMed, and Grünenthal. He received research grants from German Migraine and Headache Society, Eye on Vision Foundation, and Baasch Medicus Foundation. Henrik Winther Schytz has received honoraria from Novartis, TEVA, and Lilly and has received a research grant from Novartis. Alexandra Sinclair has received speaker fees and Honoraria from Novartis and Allergan. Andreas R. Gantenbein reports no conflicts of interest.

Publisher Copyright:
© 2021 American Headache Society

Copyright 2021 Elsevier B.V., All rights reserved.


  • diagnostic error
  • diagnostic uncertainty
  • primary headache
  • red flags
  • secondary headache

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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