Atraumatic headache is one of the most common complaints in EDs, but only a small subset of patients who present to the ED with this complaint are found to have life-threatening intracranial pathology (ICP) upon imaging. Additionally, imaging guidelines for these patients remain unclear. As a result, emergency physicians face a serious diagnostic dilemma when managing atraumatic headache, says John W. Gilbert, MD. “Imaging infrequently reveals significant findings, but results from these tests nevertheless have the potential to detect life-threatening pathology.”
Several studies have demonstrated that overall use of diagnostic imaging in the ED is increasing. The causes are thought to be multifactorial, ranging from medicolegal concerns and patient demand to the availability of diagnostic scanners that operate at ever-faster rates. This has the potential to lead to imaging overutilization with little benefit and may potentially harm patients. In clinical studies, increased use of imaging has been associated with higher costs, longer patient wait times, greater exposure to ionizing radiation, and decreased ED flow and efficiency.
“In the absence of clear evidence-based guidelines and given the potential consequences of misdiagnosis, many physicians understandably struggle when deciding whether to pursue further workup,” explains Dr. Gilbert. “In some cases, they may err on the side of increased testing. It’s important for physicians to be aware of recent trends in imaging utilization, particularly when there’s a sharp increase without obvious corresponding evidence of benefit. This information can help guide efforts toward better defining imaging criteria so that diagnostics are used appropriately.”
Imaging & Diagnostics in Atraumatic Headache
In the July 2012 Emergency Medicine Journal, Dr. Gilbert and colleagues had a study published analyzing data from the National Hospital Ambulatory Medical Care Survey of ED visits between 1998 and 2008. The analysis showed that use of CT and MRI in the evaluation of atraumatic headache increased during the 10-year study, rising from 12.5% to 31.0%. Meanwhile, the prevalence of ICP among those who received imaging decreased from 10.1% to 3.5% (Figure). “We anticipated that the imaging rate would increase, but we were surprised by the magnitude of the increase,” Dr. Gilbert says. Results also showed that average length of stay was 4.6 hours for patients with headache who received imaging versus 2.7 hours for those who did not.
According to Dr. Gilbert, 10 of the factors in the survey data examined were identified as being significantly associated with an increased likelihood of an ICP diagnosis (Table). These included age 50 or older, arrival by ambulance, triage immediacy less than 15 minutes, having systolic blood pressure of 160 mm Hg or higher or diastolic blood pressure of 100 mm Hg or higher, and disturbance in sensation, vision, speech, or motor function, including neurological weakness. “While these factors are based on a retrospective study from a national survey database and are far from comprehensive,” Dr. Gilbert explains, “they provide a basic framework for future prospective studies to develop and validate clinical decision support for imaging in this area.”
Striving for Judicious Use in Atraumatic Headache
Findings from Dr. Gilbert’s study highlight the need for clinical decision support mechanisms to guide the more judicious use of imaging in atraumatic headache. However, Dr. Gilbert also cautions that “the importance of individualized clinical judgment in deciding whether or not to order imaging for a given clinical condition cannot be overstated.” He notes that current practices should not change until prospective data from a large, well-designed study are available. Imaging appropriateness criteria also need to be better defined so that validated clinical decision support systems can be developed. In the meantime, he says physicians should remain mindful of the observed utilization trends and make every effort to ensure that each CT and/or MRI performed is appropriate.
More Work Is Needed
According to Dr. Gilbert, a crucial next step in improving imaging efficiency in atraumatic headache is the prospective derivation and validation of clinical decision support. “Ultimately, we need to develop and implement clinical decision support tools that are adequately field-tested so that we can better identify the subset of patients with atraumatic headache who require imaging. The role of pre-existing diagnoses on utilization of CT and MRI also requires further investigation. Given the changes we are currently witnessing in our healthcare system, improving clinical effectiveness and ED imaging efficiency will be of critical importance.”