Randomized clinical trials are generally regarded the gold standard in the evaluation of drug efficacy. They are designed to test therapeutic hypotheses under rather rigid conditions.
The environment in which they arise is sterile and often rather different from the conditions of real clinical practice. Such studies are characterised, on the one hand, by a high degree of internal validity, but lack, on the other hand, the option to generalise the results to a broader population.
This gap might be filled with the so-called real-world evidence studies.