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Atraumatic headache in US emergency departments: recent trends in CT/MRI utilisation and factors associated with severe intracranial pathology
  1. John W Gilbert1,
  2. Kevin M Johnson2,
  3. Gregory L Larkin3,
  4. Christopher L Moore3
  1. 1Yale School of Medicine, New Haven, Connecticut, USA
  2. 2Department of Diagnostic Radiology, Yale School of Medicine, New Haven, Connecticut, USA
  3. 3Department of Emergency Medicine, Yale School of Medicine, New Haven, Connecticut, USA
  1. Correspondence to John W Gilbert, Yale School of Medicine, Attn: Hilmer Ayuso, 464 Congress Avenue Suite 260, New Haven, CT 06519, USA; john.gilbert{at}


Objectives To estimate recent trends in CT/MRI utilisation among patients seeking emergency care for atraumatic headache in the USA and to identify factors associated with a diagnosis of significant intracranial pathology (ICP) in these patients.

Design/setting/participants Data were obtained from the USA National Hospital Ambulatory Medical Care Survey of emergency department (ED) visits between 1998 and 2008. A cohort of atraumatic headache-related visits were identified using preassigned ‘reason-for-visit’ codes. Sample visits were weighted to provide national estimates.

Results Between 1998 and 2008 the percentage of patients presenting to the ED with atraumatic headache who underwent imaging increased from 12.5% to 31.0% (p<0.01) while the prevalence of ICP among those visits decreased from 10.1% to 3.5% (p<0.05). The length of stay in the ED was 4.6 h (95% CI 4.4 to 4.8) for patients with headache who received imaging compared with 2.7 (95% CI 2.6 to 2.9) for those who did not. Of 18 factors evaluated in patients with headache, 10 were associated with a significantly increased odds of an ICP diagnosis: age ≥50 years, arrival by ambulance, triage immediacy <15 min, systolic blood pressure ≥160 mm Hg or diastolic blood pressure ≥100 mm Hg and disturbance in sensation, vision, speech or motor function including neurological weakness.

Conclusions The use of CT/MRI for evaluation of atraumatic headache increased dramatically in EDs in the USA between 1998 and 2008. The prevalence of ICP among patients who received CT/MRI declined concurrently, suggesting a role for clinical decision support to guide more judicious use of imaging.

  • Headache
  • imaging
  • CT/MRI
  • guidelines

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  • Competing interests None declared.

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

  • Data sharing statement Statistical code is available from the corresponding author at john.gilbert{at} NHAMCS dataset is publicly available online at Consent was not necessary because the presented data are anonymised as part of the NHAMCS survey methodology.

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