Your risk of bias approach might alter your conclusions

Wondering if risk of bias assessments matter? The truth is, they can dramatically affect the results of a systematic review.

In the following example, two sets of researchers, looking at the same data, reached opposite conclusions because they had different opinions about how to address risk of bias.  

They both started with the same research question:

“Does screening women using mammograms prevent death from breast cancer?”

Let’s start with the first review, conducted in 1999.