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Current Projects – HED

Authors: Tom Roberts, Dan Horner, Ann-Maree Kelly / Codes: HAP29 & CC2O / Published: 28/08/2018

Introduction

Headache in the ED? What a headache.

Serious pathology lurks in the haystack, but not everyone can have an LP, MR angiogram, CT venogram and neurology admission. How do we decide who to investigate for secondary pathology? And how do we manage primary headache syndromes to provide good patient care but discourage repeat presentation?

Acute headache accounts for between 1 – 2% of all Emergency Department attendances, estimated at >350,000 UK patients per year 1. Some of these patients will have serious pathology as the underlying cause of headache, as high as 10% in some studies 2. Unfortunately, subjective clinical headache features and examination findings are often unreliable discriminators. We pursue high rates of invasive investigation and hospital admission in an attempt to avoid diagnostic error and reassure both patients and ourselves.

Yet we also know that invasive diagnostic strategies are not without harm. Advanced neuroimaging can lead to incidental findings in over 2% of patients, which can create anxiety and necessitate further testing or surgical procedures 3. Lumbar puncture to definitively exclude subarachnoid haemorrhage can lead to increased length of hospital stay, pain/suffering and other recognised complications. Recent evidence also suggests the benefits of this additional invasive test are likely to only apply to a small proportion of CT negative patients with a high pretest probability 4.

In a large emergency medicine case series, >50% of headaches were classed as primary at reference standard diagnosis 5. There is also increasing guidance from the National Institute for Health and Care Excellence regarding the avoidance of acute neuroimaging when feasible 6. Emergency physicians are faced with the challenge of selecting appropriate patients to undergo invasive testing, without missing significant underlying causes, in the absence of validated risk prediction.

Several strategies have recently been published to aid in this challenge. Clinical decision rules are well established in emergency medicine practice as unidirectional decision aids that can support the omission of advanced imaging and limit invasive testing 7-9. Similar rules have been derived to limit invasive testing in acute headache 10,11. These rules are yet to be validated in a European population.

In addition, several studies have recently focussed on the sensitivity of CT imaging alone for the exclusion of subarachnoid haemorrhage (SAH) in patients attending the emergency department early 12. A systematic review including > 8000 patients in 2016 reported a sensitivity of 0.99 (95% CI 0.97 to 0.99) for the diagnosis when a CT was performed within 6h of headache onset in patients without focal neurological deficit 13. These results are also yet to be adopted into national clinical practice or consensus guidelines, due to limited validation studies and some papers disputing the high reported sensitivity 14,15. Are you using this strategy in your department? Do you use the Ottawa SAH rule to limit your neuroimaging full stop? Would you like to see how both these rules perform in a pragmatic national UK study?

What is HED planning to look at?

We plan to prospectively recruit a large cohort of patients with headache as a primary reason for ED attendance, collecting routine data on presentation features, investigations and correlating this against reference standard diagnosis. We can then use this data to address multiple research questions. We plan to primarily attempt external validation of both the Ottawa subarachnoid haemorrhage rule and 6-hour CT only rule out strategy in suspected SAH; the latter topic was recently listed within the top 30 emergency medicine research priorities, by patients and clinicians 16.

What are the specific aims of this project?

In addition to the above, with a large cohort of acute headache patients we can provide demographic and epidemiological data on this issue at scale. We can also look at variation in management strategies across the country, both for management of primary headache syndromes and investigation of potential secondary headaches. There is a pressing need to explore treatment variation and correlation with national guidance in this cohort also.

The Australians are launching a similar study (HEAD) within the same time period looking to collect a similar data pool. This offers fantastic opportunity for collaboration with the HEAD study group and an exciting opportunity to develop an international dataset and report demographics, variation in practice and outcome across continents.

From a methodological perspective, we plan to use this study to assess new ways of pragmatic data capture. As trainees, we all collect these clinical features as part of our routine assessment. We plan to work with clinicians to generate simple data collection tools that can serve as clinical documentation, rather than expecting busy trainees to complete onerus case report forms full of duplication.

What will this study add for patients?

This study will provide scientific rationale for widespread adoption of tailored diagnostic strategies in acute headache. It will also describe modern patterns of headache pathology across the country; as such patients will gain insight to rates of diagnosis, performance of clinical decision rules and yield of invasive testing. This information will change the landscape of shared decision making for this challenging presentation. We will also work with patients during this study to design information sheets, safety net documentation and educational materials designed to explain risk thresholds and ensure appropriate explanation of assessment.

What will this study add for clinicians?

Use of a highly sensitive decision rule to predict the need for invasive testing could further limit neuroimaging, lumbar puncture and invasive testing within the acute sector, thus reducing opportunity costs through savings in clinician time, hospital admissions and radiological investigations. In addition, validation of those characteristics suggested as ‘red flags’ for headache pathology by national bodies could further streamline appropriate resource use and tailored diagnostics; clinicians could be confident about which patients needed thorough evaluation, and which could be managed as a primary headache syndrome initially.

This research project was the top scorer at the TERN scoping meetings; it will not only galvanise and enthuse a generation of trainees by providing research opportunity for a project selected by them, but also has the potential to lead knowledge translation regarding previous headache work. If these rules are validated within a large dataset of patients based on trainee medical assessments, this should provide inherent confidence in acutely translating these findings into mainstream practice.

This is also a fantastic opportunity to collaborate with an established and respected research group in Australia. We hope to cement links over the course of this project which will lead to future collaborations.

What is the timeline for this project?

Our funding application is in for this study and we are currently pursuing ethical approval. We expect to start recruitment in Spring 2019. The time line for the project is described below.

Duration (months) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Ethical review and approvals 2
Study set up 2
Recruitment 6
Follow up 6
Data entry and analysis 8
Write up and publication 2

Anything else I should know?

Not really. We have had expressions of interest for the first TERN projects from over 100 trainees. We are excited about getting on with this. Representatives have been appointed in your region who will be driving the process and should be talking to you about this soon at regional study days. In addition, they should have ideas about how you can use your study leave to help with this, how participation will contribute to your eportfolio and ARCP requirements and how you will be recognised for participating in the research.

If you want more information on this study in particular, drop us a line at tern@rcem.ac.uk. You can also look at the other Tiles for information on how to sign up to TERN and get on the mailing list.

Emergency Department, Bristol Royal Infirmary, Bristol, UK

Emergency Department, Salford Royal NHS Foundation Trust, Manchester, UK

Joseph Epstein Centre for Emergency Research, Melbourne, Australia

References:

  1. Edlow JA, Caplan LR. Avoiding pitfalls in the diagnosis of subarachnoid hemorrhage. N Engl J Med 2000; 342(1): 29-36.
  2. Dhopesh V, Anwar R, Herring C. A retrospective assessment of emergency department patients with complaint of headache. Headache 1979; 19(1): 37-42.
  3. Morris Z, Whiteley WN, Longstreth WT, Jr., et al. Incidental findings on brain magnetic resonance imaging: systematic review and meta-analysis. BMJ 2009; 339: b3016.
  4. Carpenter CR, Hussain AM, Ward MJ, et al. Spontaneous Subarachnoid Hemorrhage: A Systematic Review and Meta-analysis Describing the Diagnostic Accuracy of History, Physical Examination, Imaging, and Lumbar Puncture With an Exploration of Test Thresholds. Acad Emerg Med 2016; 23(9): 963-1003.
  5. Locker TE, Thompson C, Rylance J, Mason SM. The utility of clinical features in patients presenting with nontraumatic headache: an investigation of adult patients attending an emergency department. Headache 2006; 46(6): 954-61.
  6. National, Institute, for, et al. Diagnosis and management of headache in young people and adults. CG150. 2012. https://www.nice.org.uk/guidance/cg150 (accessed 31/7/2018 2018).
  7. Rodriguez RM, Hendey GW, Mower WR. Selective chest imaging for blunt trauma patients: The national emergency X-ray utilization studies (NEXUS-chest algorithm). Am J Emerg Med 2017; 35(1): 164-70.
  8. Stiell IG, Clement CM, Grimshaw J, et al. Implementation of the Canadian C-Spine Rule: prospective 12 centre cluster randomised trial. BMJ 2009; 339: b4146.
  9. Stiell IG, Lesiuk H, Wells GA, et al. Canadian CT head rule study for patients with minor head injury: methodology for phase II (validation and economic analysis). Ann Emerg Med 2001; 38(3): 317-22.
  10. Perry JJ, Sivilotti MLA, Sutherland J, et al. Validation of the Ottawa Subarachnoid Hemorrhage Rule in patients with acute headache. CMAJ 2017; 189(45): E1379-E85.
  11. Kimura A, Kobayashi K, Yamaguchi H, et al. New clinical decision rule to exclude subarachnoid haemorrhage for acute headache: a prospective multicentre observational study. BMJ Open 2016; 6(9): e010999.
  12. Perry JJ, Stiell IG, Sivilotti ML, et al. Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study. BMJ 2011; 343: d4277.
  13. Dubosh NM, Bellolio MF, Rabinstein AA, Edlow JA. Sensitivity of Early Brain Computed Tomography to Exclude Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis. Stroke 2016; 47(3): 750-5.
  14. Mark DG, Kene MV, Udaltsova N, Vinson DR, Ballard DW. Sensitivity of a Clinical Decision Rule and Early Computed Tomography in Aneurysmal Subarachnoid Hemorrhage. West J Emerg Med 2015; 16(5): 671-6.
  15. Mark DG, Sonne DC, Jun P, et al. False-negative Interpretations of Cranial Computed Tomography in Aneurysmal Subarachnoid Hemorrhage. Acad Emerg Med 2016; 23(5): 591-8.
  16. Smith J, Keating L, Flowerdew L, et al. An Emergency Medicine Research Priority Setting Partnership to establish the top 10 research priorities in emergency medicine. Emerg Med J 2017; 34(7): 454-6.

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