Journal Club Summary

Methodology Score: 4/5
Usefulness Score: 5/5

Nogueira RG, et al. N Engl J Med. 2018 Jan 4;378(1):11-21

Editorial: A New DAWN for Imaging-Based Selection in the Treatment of Acute Stroke. 

Questions and Methods: DAWN was an open-label multi-centre RCT assessing functional outcomes of embolectomy compared with standard medical therapy for patients presenting after 6 hours or awakening and confirmed anterior circulation large vessel occlusion (LVO) and large clinical-imaging mismatch.

Findings: Functional independence at 90 days was achieved in 49% of patients in the embolectomy group compared with 13% in the standard medical therapy group, yielding a number needed to treat (NNT) of 3.

Limitations: The generalizability of this trial is limited to centres using the proprietary RAPID perfusion software for patient selection.

Interpretation: DAWN influenced the AHA and CSBPR guidelines to highlight that patients with LVO ischemic strokes presenting beyond 6 hours should be considered for embolectomy if meeting DAWN criteria.
Dr. Miguel Cortel 

Epi lesson

Bayesian analysis

There are two fundamental ways of statistical analysis. Frequentist analysis report one fixed value (the common type of analysis performed in most research studies). Whereas in Bayesian analysis the parameter is summarized by an entire distribution of values called posterior distribution of the parameter of interest based on the actual study ± prior literature. Bayesian analysis is very unique in that we can incorporate prior literature evidence, use the actual study results to come up with the posterior distribution. In DAWN trial, the investigators report the posterior probability of superiority of the intervention compared to the control arm.
Dr. Venkatesh Thiruganasambandamoorthy


  • 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.