May 2008 Journal Club

A bit late, but here's the details from the May Journal Club. Dr. Hirsh blew us away with her culinary skills, and her awesome new kitchen. The articles were great too, but clearly took a back seat to the food!



1) Byyny, RL, et. al. Sensitivity of Noncontrast Cranial Computed Tomography for the Emergency Department of Subarachnoid Hemorrhage. Annals of Emergency Medicine 2008 (Article in press)

The article asks whether new multi-detector CT scanners are sensitive enough to rule out SAH without performing an LP.

Design:
Retrospective chart review of patient diagnosed in the ED with SAH at a tertiary care academic medical center with an annual volume of 40,000. Patients were identified by ICD-9 codes, and charts were reviewed to see whether they had a CT or LP in the ED. All patients with SAH were scanned with a 4-detector CT scanner.

Results:
149 patients with ED diagnosis of SAH were identified. Non-contrast CT identified 139 of these, yielding a sensitivity of 93% (95% CI 88% to 97%). Of patients with diagnosed SAH and a normal mental status, CT was 91% sensitive, whereas it missed only 1/61 in patients with an abnormal mental status. The authors conclude that a normal non-contrast CT scan is insufficient for ruling out SAH in the ED population.

Discussion points:
The group agreed that while this studies has some flaws, it does demonstrate that CT scanning alone is not sufficient to rule out SAH. The overall sensitivity of 90-95% is similar to the performance of early generation CT scanners, and we agreed that lumbar puncture still needs to be performed when evaluating for subarachnoid bleeding.

One concern with this paper is that it enrolled only patients with diagnosed SAH, which likely missed a substantial number of people with headache discharged after a normal head CT. It is possible, then, that there were patients discharged from the ED with a missed SAH as they did not have further testing performed after a negative CT. This would lower the sensitivity of the scan even further.

Another question raised by the group was whether the sensitivity would improve with a 16-, 32-, or 64-slice scanner. I suspect we will see more studies coming out addressing this question. Until then, we'll all still be doing LPs.

Article number 2 coming soon....