How confounding by indication can indicate problems in observational research on the effectiveness of an intervention!

Observational research is an important method in evidence-based medicine, especially when it is performed to support or assess effectiveness results from randomized controlled trials. An unwanted (but not always observable) confounder in observational research is confounding by indication and should be eliminated from the research design when possible for the results to be meaningful. Let’s find out what this confounder is!