Conclusions
We sought to address one of the most crucial clinical question in
contemporary clinical research: how large of an effect size is large
enough to circumvent the need for further RCTs testing by the regulatory
agencies? Our results suggest that drug developers can use the change in
one logarithm of effect size as a benchmark to decide if further testing
in RCTs should be pursued, or as a guide to interpreting the results
reported in non-randomized studies. Further research would be helpful to
better characterize the threshold of effect size above which testing in
RCTs is not needed.