Clinical trial generalizability assessment in the big data era: a review

Clinical studies, especially randomized controlled trials, are essential for generating evidence for clinical practice.  However, generalizability is a long-standing concern when applying trial results to real-world patients.  Generalizability assessment is thus important, nevertheless, not consistently practiced.  We performed a systematic scoping review to understand the practice of generalizability assessment.  We identified 187 relevant papers and systematically organized these studies in a taxonomy with three dimensions: (1) data availability (i.e., before or after trial [a priori vs a posteriori generalizability]), (2) result outputs (i.e., score vs non-score), and (3) populations of interest.  We further reported disease areas, underrepresented subgroups, and types of data used to profile target populations.  We observed an increasing trend of generalizability assessments, but less than 30% of studies reported positive generalizability results.  As a priori generalizability can b...