Date: February 18th, 2019

Guest Skeptic: Dr. Shahriar Zehtabchi is a tenured professor and Vice Chair of Academic Affairs in the Department of Emergency Medicine at SUNY Downstate Medical Center & Kings County Hospital. He has been teaching evidence-base medicine for many years and currently is the editor-in-chief of the EBM website TheNNT.com. Shahriar also serves as an editorial board member and associate editor for Academic Emergency Medicine journal.

Dr. Shahriar Zehtabchi

Shahriar and I discussed the following:

  • The NNT and NNH as a concept
  • How to use the NNT/NNH to communicate with patients
  • Weaknesses of the NNT
  • What topics are covered on TheNNT.com and how they are selected
  • Their peer review process for quality control
  • Whether or not they have a policy to identify conflicts of interest
  • Dr. Zehtabachie’s role as editor-in-chief

Guest Skeptic: Dr. Eddy Lang is a Professor and Department Head for Emergency Medicine Cumming School of Medicine, University of Calgary, Scientific Director Emergency Strategic Clinical Network and BEEM faculty member.

TheNNT.com updated their website January 11th, 2019 changing the recommendation of tPA for acute stroke from RED (no benefit) to GREEN (benefit > harms). Eddy was the lead author of the new recommendation and when it was posted it got the twitterverse very excited.

Dr. Eddy Lang

I reached out to Dr. Hoffman to discuss this change.  Then Eddy was invited to come on the SGEM to discuss why the change was made.

Eddy and I talked about the following:

  • My stated position on thrombolysis for acute CVA
  • His impression of the twitter storm
  • His stated position on thrombosis for acute CVA and synopsis of the evidence
  • Why he picked Dire Straights the Walk of Life as the theme music
  • The claim that the modified Rankin Scale (mRS) is reliable and validated
  • Limitations/weaknesses of the IST-3 Trial
  • GRADE Methodology
  • Inclusion and exclusion of different thrombolytic molecules in SRMAs
  • Various guidelines
  • Emberson et al SRMA from the Lancet
  • Why they changed the recommendation from RED to GREEN
  • The claim that time is brain
  • ~1/3 of stroke are determined to be mimics
  • Thrombolysing patients without strokes (mimics)
  • Need for replication of trials in medicine
  • The ethics of replicating the NINDS trial
  • What Eddy says to patients/family at the bedside
  • The impact of conflicts of interest in the production and interpretation of the literature

Each of us will have different levels of evidence that will convince us to change our practice. I respect that two people can look at the same literature and come to a different conclusion. The burden of proof is on those making the positive claim that tPA results in a net patient-oriented benefit in acute ischemic stroke. In my opinion, the burden of proof has not been met and I remain skeptical. I am happy to change my mind if presented with stronger evidence.


Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine.


Additional Resources:

  • SketchyEBM – Knowing NNT
  • Chiong et al. Testing the Presumption of Consent to Emergency Treatment for Acute Ischemic Stroke. JAMA 2014
  • Banks and Marotta. Outcomes Validity and Reliability of the Modified Rankin Scale: Implications for Stroke Clinical Trials. A Literature Review and Synthesis. Stroke 2007 
  • Tsivgoulis et al. Safety of intravenous thrombolysis in stroke mimics: prospective 5-year study and comprehensive meta-analysis. Stroke 2015
  • Kamal et al. Improving Door-to-Needle Times for Acute Ischemic Stroke: Effect of Rapid Patient Registration, Moving Directly to Computed Tomography, and Giving Alteplase at the Computed Tomography Scanner. Circ Cardiovasc Qual Outcomes 2017
  • Harris et al. Treatment of Stroke in Canadian Emergency Departments: Time to be Leaders. CJEM 2017
  • Kamal et al. Good is not Good Enough: The Benchmark Stroke Door-to-Needle Time Should be 30 Minutes. Can J Neruo Sci 2014
  • What is GRADE (subjectivity). BMJ Best Practices 
  • Finding What Works in Health Care Standards for Systematic Reviews. Standards March 2011
  • ACEP Clinical Policy: Use of Intravenous Tissue Plasminogen Activator for the Management of Acute Ischemic Stroke in the Emergency Department. Annals of EM 2015
  • ACEM Statement on Intravenous Thrombolysis for Ischaemic Stroke. ACEM 2017
  • CAEP Position Statement on Acute Ischemic Stroke. CJEM 2015
  • Wardlaw et al. Thrombolysis for acute ischaemic stroke. Cochrane 2009
  • Wardlaw et al. Thrombolysis for acute ischaemic stroke. Cochrane 2014
  • Baker M. 1,500 scientists lift the lid on reproducibilityReplication. Nature 2016
  • Stroke Mimics
  • Easton et al. Definition and Evaluation of Transient Ischemic Attack. Stroke 2009
  • Lenzer J. Why we can’t trust clinical guidelines. BMJ 2013 
  • Boulanger et al. Canadian Stroke Best Practice Recommendations for Acute Stroke Management: Prehospital, Emergency Department, and Acute Inpatient Stroke Care, 6th Edition, Update 2018. International Stroke Journal July 2018
  • Clinical Guidelines for Stroke Management 2017. InformMe