It is generally believed that bias is minimized in well-controlled randomized clinical trials. However, bias can arise in active controlled noninferiority trials because the inference relies on a previously estimated effect size obtained from a historical trial that may have been conducted for a different population. By implementing a likelihood reweighting method through propensity scoring, a study designed to estimate a treatment effect in one trial population can be used to estimate the treatment effect size in a different target population. We illustrate this method in active controlled noninferiority trials, although it can also be used in other types of studies, such as historically controlled trials, meta-analyses, and comparative effectiveness analyses.
"Likelihood reweighting methods to reduce potential bias in noninferiority trials which rely on historical data to make inference." Ann. Appl. Stat. 7 (3) 1796 - 1813, September 2013. https://doi.org/10.1214/13-AOAS655