CT Changes Headache Workup

Recent studies have raised concerns about whether CT is overused in the emergency setting for patients with symptoms like headache, but a new study in JAMA Network Open suggests that higher CT utilization could be contributing to a decline in more invasive procedures like lumbar puncture. 

Earlier this month, we covered a study documenting the rapid rise of emergency head CT for patients presenting with acute-onset headache – which could be an indication of subarachnoid hemorrhage or other serious issues. 

  • Researchers theorized that higher CTA utilization could be a sign of overuse because the rate of positive findings over time fell 38%.

But the new study suggests that the growth in cerebral CTA use could have beneficial effects, by reducing the use of more invasive procedures and by detecting unruptured intracranial aneurysm. 

  • Some 5% of acute-onset headaches in emergency patients are caused by subarachnoid hemorrhage; these cases have a 50% risk of death or serious disability at one year, making accurate detection and workup a serious issue.

Researchers from Kaiser Permanente in Northern California analyzed 198k encounters for patients with headache at 21 community EDs from 2015 to 2021. 

  • They compared multiple workup protocols, ranging from CT only to others in which CT was used first, with nondiagnostic cases sent to either lumbar puncture or cerebral CTA. 

Dramatic changes occurred in headache workup over the study period, including … 

  • Overall use of CT grew at an average annual percent change of 5.4%
  • Cerebral CTA use grew 19% annually
  • Lumbar puncture use fell 11% annually
  • Detection of unruptured intracranial aneurysms grew 33%
  • The ratio of unruptured aneurysms to subarachnoid hemorrhage grew

The authors noted that the findings show clinicians are shifting away from a headache workup protocol that includes lumbar puncture to one that relies more on cerebral CTA.

  • The researchers were equivocal on the increase in detection of unruptured aneurysms; on the one hand, the absolute risk of rupture is low, but on the other, the consequences of rupture are severe.  

The Takeaway

The new study offers a more nuanced – and perhaps more positive – view of growing cerebral CTA use in the ED. In the end, it’s possible that two conflicting statements can be true: CT indeed may be overused in the emergency department, but its growing use is also having a beneficial impact on patient care.

Spotlight on ED Diagnostics

A new U.S. federal government study made emergency department diagnostic accuracy a mainstream news story, showing that although ED diagnostic errors are somewhat rare, they occur in high volumes and can carry serious consequences. 

The U.S. Agency for Healthcare Research and Quality and Johns Hopkins University teamed up to analyzed 279 international studies published between 2001 and 2021, finding that:

  • Diagnostic errors occur in an estimated 5.7% of ED visits
  • Generalized to the U.S., ED diagnostic errors impact 7.4M patients annually
  • Those diagnostic errors lead to “preventable harms” in roughly 2.6M patients, and “serious harms” in 371k patients, including 250k deaths
  • The top 5 and 15 diseases account for 39% and 68% of “serious misdiagnosis-related harms” 

Although “not all diagnostic errors are preventable,” error rate variations revealed key areas for improvement:  

  • Women and people of color were 20% to 30% more likely to be misdiagnosed
  • Misdiagnosis is far more common among patients with “atypical” and “subtle” disease presentation
  • Hospital and disease-specific error rates varied widely

Imaging played a major role in the study, as most of the top-15 diseases associated with “serious misdiagnosis-related harms” are typically diagnosed with imaging exams (including all of the top-5), and the report mentioned “radiology,” “imaging,” “image,” “scan,” or “ultrasound” a whopping 419 times.

Emergency medicine societies objected to these results, but the consensus among study authors and most observers was that more efforts are needed to understand and address ED diagnostic errors, with a specific focus on the diseases associated with serious misdiagnosis harms.

The Takeaway

Most efforts to improve ED safety over the last 20 years have targeted glaring mistakes (e.g. wrong medications, ED-acquired infections), but this report clearly calls for increased focus on improving EDs’ diagnostic accuracy. 

Those efforts would start at the bedside, but they would definitely involve medical imaging (and potentially error-catching AI tools), especially considering that most of the diseases associated with “serious misdiagnosis-related harms” are diagnosed via imaging.

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