Journal Club Summary

Methodology Score: 4/5                   
Usefulness Score:  2/5
Zemek R, et al.
JAMA. 2016 Mar 8;315(10):1014-25.
Babcock L, et al.
JAMA. 2016 Mar 8;315(10):987-8.
This was a prospective multicenter cohort study of pediatric patients with acute concussion that derived and validated a clinical decision rule with modest discrimination to assess risk of persistent postconcussion symptoms at 28 days.  The group felt that while very methodologically sound it would have limited role in the ED given the lack of validated treatment options for concussion but it may have a role to develop a high risk group to target further research.
By: Dr. Rory Connolly

Epi lesson

What is Collinearity? Why does it Matter? How do you Measure it?

Collinearity means that two of the predictors entered in a regression analysis model correlate with each other (they measure almost the same thing, e.g. %body fat and total body weight). When more than two predictors interact with each other, it is called multicollinearity.
Collinearity can be a problem, especially when very high, since the software will simply not be able to perform the regression analyses, or will provide unreliable results. The degree of collinearity can be estimated using the Variance Inflation Factor (VIF) which should be <5-10.
By: Dr. Christian Vaillancourt