Journal Club summary
Methodology Score: 2/5
Usefulness Score: 2/5
Szelényi Z, et al. Acad Emerg Med. 2013 Nov;20(11):1121-30.
This retrospective cohort study found that the Vereckei algorithm for differentiating between VT and SVT with aberrancy on wide complex tachycardia (WCT) EKGs in a non-clinical setting had a sensitivity and specificity of 92.4% and 64.7% for identifying VT, while the RWPT algorithm had a sensitivity and specificity of 79.1% and 80.9%. JC attendees identified multiple methodological errors and sources of potential bias in the study, and overall were concerned with an unacceptable miss rate for a potentially deadly diagnosis. It was agreed that it is safest to manage most WCTs as VT in an ED setting, with the exact role of these algorithms left unclear.
By: Dr. Francis Bakewell
Epi Lesson: Why sample size calculations are important
A sample size is calculated in order to:
1) determine the power of a study and 2) reduce the chance of sampling error. When authors provide a sample size calculation, the critical reader can determine whether the power is adequate and whether the underlying assumptions are valid. Without this, there is a high risk of an underpowered study with an imprecise estimate of overall effect.
By: Dr. Lisa Calder