Methodology: 4/5
Usefulness: 4/5

Perry JJ, et al. Stroke. 2020 Feb;51(2):424-430. doi: 10.1161/STROKEAHA.119.026969.

Question and Methods: Prospective, multi-center before and after study looking at the implementation of the Ottawa Subarachnoid Hemorrhage Rule and 6-Hour CT Rule.
Findings: Implementation of the Ottawa SAH Rule did not affect the rate of CT ordering. Implementation of the 6-Hour CT rule decreased testing beyond initial CT. Both rules were highly sensitive.
Limitations: Many clinicians were using the rules in the control phase. Unlike prior studies, there was no telephone follow-up.

Interpretation: The Ottawa SAH Rule and 6-Hour CT rule are highly sensitive and may help to standardize the ED work-up of SAH. 

By: Dr. Michael Hale

Hans Rosenberg
Dr. Rosenberg is an emergency physician at the Ottawa Hospital, assistant professor at the University of Ottawa, and Director of the Digital Scholarship and Knowledge Dissemination Program.