On the Shoulders of Giants
Don’t miss the additional reading below…this article is worth it!
The ALiEM 52 in 52 list chose the SAH derivation study as a landmark article, but the authors subsequently did a larger, external validation study published in JAMA in 2013. This is where I will focus. The original article derived 3 clinical prediction rules that may reduce the need for SAH workup in some patients, all of which were 100% sensitive.
The 2013 study externally validated these results and refined them to come up with the Ottawa SAH Rule, which was 100% sensitive, 15% specific. It consisted of:
- Age ≥40
- Neck pain or stiffness
- Witnessed loss of consciousness
- Onset during exertion
- Thunderclap headache (instantly peaking pain)
- Limited neck flexion on examination
The inclusion/exclusion criteria were very stringent in this study, so make sure you know if the patient in front of you reflects the type of patient included in the study. See the box on MD Calc before using the calculator.
Spoon Feed
The Ottawa SAH Rule is helpful in deciding which patients need further workup in the ED, but make sure your patient is similar to those included in the validation study.
Sources
- Derivation Study – High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study. BMJ. 2010 Oct 28;341:c5204. doi: 10.1136/bmj.c5204.
- Validation Study – Clinical decision rules to rule out subarachnoid hemorrhage for acute headache. JAMA. 2013 Sep 25;310(12):1248-55. doi: 10.1001/jama.2013.278018.
Another Spoonful
- MD Calc has one of the best brief, free summaries of this in the #FOAMed world. They interview lead author Perry for his insights. Do your patients a favor and READ THIS!
- And don’t miss the ALiEM Global Journal Club on this article and Google Hangout with two of the authors. They published answers to the questions raised in this Annals of EM article (with free full text).
