Rule Out SAH with… The Ottawa Subarachnoid Hemorrhage Rule

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What’s better than a champagne tap? Not having to do an LP in the first place.

THE GOOD
Why Use It
+~100% sensitive for SAH + The only wellvalidated calc for SAH rule-out

THE BAD
Limitations
– Strict inclusion criteria, so only applicable to small number of patients
– 40 years or older? (a.k.a. every patient in the ED) automatic fail

THE UGLY
Misapplication
× Underinvestigation: failure to act on neck painor stiffness
× Overinvestigation: interpretation of “thunderclap” headache; don’t apply rule if you’re not suspicious for SAH

DERIVATION:  1,999 pts, 5 Canadian centers, prospectively enrolled, 3 different CDRs with sens 100%, spec 28-39%

VALIDATION:  2,131 pts, 10 Canadian centers, prospective external cohort, sens 100%, spec 15%

REFERENCES

1. Perry JJ, Stiell IG, Sivilotti ML, et al. High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study. BMJ. 2010;341:c5204.
2. Perry JJ, Stiell IG, Sivilotti ML, et al. Clinical decision rules to rule out subarachnoid hemorrhage for acute headache. JAMA. 2013;310(12):1248-55.

ABOUT THE AUTHOR

Joseph Habboushe, MD, MBA is an attending at Beth Israel. He is the creator and editor of EMRA's Basics of Emergency /medicine pocket guide and iphoneapp.

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