Use of CT scans for the investigation of headache: a report from ASPN, Part 1.

Background: Clinicians in the Ambulatory Sentinel Practice Network (ASPN) order computed tomography (CT) scans for approximately 3% of patients with headache. This study was undertaken to provide information about the reasons for ordering CT scans and the results obtained.
Methods: Weekly return cards were used to collect data on every patient for whom a CT scan was ordered to investigate a headache during a 19-month period. Copies of CT reports were reviewed, and a chart audit was performed to collect further clinical information whenever an intracranial tumor, subarachnoid hemorrhage (SAH), or subdural hematoma (SDH) was reported.
Results: Clinicians in 58 practices ordered 349 CT scans. Only 52 patients (15%) had abnormalities noted on neurological examination. Most CT scans were ordered because the clinician believed that a tumor (49%) or an SAH (9%) might be present. Fifty-nine (17%) were ordered because of patient expectation or medicolegal concerns. Of the 293 reports reviewed, 14 indicated that a tumor, an SAH, or an SDH was present. Two of the 14 (14%) were false positives. Forty-four (15%) of the reports noted incidental findings of questionable significance.
Conclusions: Because there are no clear guidelines for the use of CT for the investigation of headache, physicians must exercise good clinical judgment in their attempts to identify treatable disease in a cost-effective manner. ASPN clinicians made selective use of CT scans based on a combination of factors that included physician and patient concerns. CT was an imperfect tool in this setting. Most of the positive results represented false positives or incidental findings that could have led to adverse effects and additional costs.