[How to measure real-world effectiveness?]

The new use of medico-administrative databases is a major change in the medical assessment field. Given the limits of the randomized clinical trials when it comes to accurately represent the heterogeneity and complexity of medical care in a real-world context, an increasing demand of observational studies comes from healthcare systems as decision tools. The lack of intervention generates real-world data and assesses both the care and the outcomes of patients in routine practice. Despite this external validity, the bias and confounding factors are a challenge to the internal validity of observational studies. An appropriate study design and statistical methods are necessary to neutralize them and consider a causal relationship between a treatment and a clinical outcome.