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Predictive performance of the common red flags in emergency department headache patients: a HEAD and HEAD-Colombia study
  1. Kevin Chu1,
  2. Anne-Maree Kelly2,3,
  3. Win Sen Kuan4,
  4. Frances B Kinnear5,6,
  5. Gerben Keijzers7,
  6. Daniel Horner8,
  7. Said Laribi9,
  8. Alejandro Cardozo10,
  9. Mehmet Akif Karamercan11,
  10. Sharon Klim2,
  11. Tissa Wijeratne12,
  12. Sinan Kamona13,14,
  13. Colin A Graham15,
  14. Richard Body16,17,
  15. Tom Roberts18,19
  16. HEAD and HEAD-Colombia study groups
  1. 1 Emergency and Trauma Centre, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
  2. 2 Joseph Epstein Centre for Emergency Medicine Research, Western Health, Footscray, Victoria, Australia
  3. 3 Department of Critical Care, The University of Melbourne, Melbourne, Victoria, Australia
  4. 4 Emergency Medicine Department, National University Hospital, Singapore
  5. 5 Emergency and Children's Services, The Prince Charles Hospital, Brisbane, Queensland, Australia
  6. 6 Department of Medicine, University of Queensland, Brisbane, Queensland, Australia
  7. 7 Department of Emergency Medicine, Gold Coast University Hospital, Southport, Queensland, Australia
  8. 8 Emergency Department, Salford Royal NHS Foundation Trust, Salford, UK
  9. 9 Emergency Medicine Department, Tours University Hospital, Tours, France
  10. 10 Instituto Neurológico de Colombia, Medellin, Colombia
  11. 11 Department of Emergency Medicine, Gazi University Faculty of Medicine, Ankara, Turkey
  12. 12 Department of Neurology, Western Health, Footscray, Victoria, Australia
  13. 13 School of Medicine, University of Auckland, Auckland, New Zealand
  14. 14 Auckland City Hospital, Auckland District Health Board, Auckland, New Zealand
  15. 15 Emergency Medicine, Chinese University of Hong Kong - Prince of Wales Hospital, Sha Tin, Hong Kong
  16. 16 Emergency Department, Manchester University NHS Foundation Trust, Manchester, UK
  17. 17 Division of Cardiovascular Sciences, University of Manchester, Manchester, UK
  18. 18 Trainee Emergency Research Network, London, UK
  19. 19 North Bristol NHS Trust, Bristol, UK
  1. Correspondence to Professor Anne-Maree Kelly, JECEMR, Western Health, Footscray, VIC 3011, Australia; anne-maree.kelly{at}


Objectives Only a small proportion of patients presenting to an ED with headache have a serious cause. The SNNOOP10 criteria, which incorporates red and orange flags for serious causes, has been proposed but not well studied. This project aims to compare the proportion of patients with 10 commonly accepted red flag criteria (singly and in combination) between patients with and without a diagnosis of serious secondary headache in a large, multinational cohort of ED patients presenting with headache.

Methods Secondary analysis of data obtained in the HEAD and HEAD-Colombia studies. The outcome of interest was serious secondary headache. The predictive performance of 10 red flag criteria from the SNNOOP10 criteria list was estimated individually and in combination.

Results 5293 patients were included, of whom 6.1% (95% CI 5.5% to 6.8%) had a defined serious cause identified. New neurological deficit, history of neoplasm, older age (>50 years) and recent head trauma (2–7 days prior) were independent predictors of a serious secondary headache diagnosis. After adjusting for other predictors, sudden onset, onset during exertion, pregnancy and immune suppression were not associated with a serious headache diagnosis. The combined sensitivity of the red flag criteria overall was 96.5% (95% CI 93.2% to 98.3%) but specificity was low, 5.1% (95% CI 4.3% to 6.0%). Positive predictive value was 9.3% (95% CI 8.2% to 10.5%) with negative predictive value of 93.5% (95% CI 87.6% to 96.8%).

Conclusion The sensitivity and specificity of the red flag criteria in this study were lower than previously reported. Regarding clinical practice, this suggests that red flag criteria may be useful to identify patients at higher risk of a serious secondary headache cause, but their low specificity could result in increased rates of CT scanning.

Trial registration number ANZCTR376695.

  • headache
  • emergency department

Data availability statement

Data are available upon reasonable request. Data may be available subject to HREC approval.

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Data availability statement

Data are available upon reasonable request. Data may be available subject to HREC approval.

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  • Handling editor Carl Marincowitz

  • X @kellyam_jec, @rcemprof, @richardbody, @DrTomRoberts

  • Contributors KC and A-MK had the concept for the study. The authors codesigned the study and facilitated data collection. KC undertook the analysis and is the guarantor for this work. All authors had input into interpretation of the results. A-MK drafted the manuscript. All authors contributed to refinement of the manuscript.

  • Funding The Royal College of Emergency Medicine (UK) provided part funding (G/2018/1).

  • Competing interests RB is deputy editor of EMJ.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.