Observational designs for real-world evidence studies

In the era of evidence-based medicine, real-world evidence (RWE) studies have opened avenues to utilize real-world data (RWD) effectively for improving clinical decision-making. However, the transformation of RWD into a meaningful RWE can only be achieved when the researcher asks the right clinical question, selects the right RWD source for variables of interest, uses the right study design, and applies the right statistical analysis. The generated RWE needs to have internal as well as external validity to be actionable. The "fit-for-purpose" observational study designs include descriptive, case-control, cross-sectional, and cohort. This article focuses on the advantages and disadvantages including the inherent bias of each study design. The RWE study decision guide has also been provided to aid the selection of appropriate study designs.