手法を比較

	後向き第III相臨床試験	ランダム化比較試験 (RCT)
分野	疫学	疫学
系統	Process / pipeline	Process / pipeline
提唱年	Late 20th century (ICH E8 1997; widespread retrospective Phase III use from 1990s onward)	1948 (first rigorously conducted RCT — MRC streptomycin trial)
提唱者	Regulatory framework codified by ICH E8/E9 (1997–1998); retrospective application developed through post-marketing and registry practice	Austin Bradford Hill; MRC Streptomycin Trial team
種類	Retrospective comparative clinical study	Interventional experimental study
原典	Friedman, L. M., Furberg, C. D., & DeMets, D. L. (2010). Fundamentals of Clinical Trials (4th ed.). Springer. ISBN: 978-1441915856	Friedman, L. M., Furberg, C. D., DeMets, D. L., Reboussin, D. M., & Granger, C. B. (2015). Fundamentals of Clinical Trials (5th ed.). Springer. ISBN: 978-3319185385
別名	retrospective Phase III study, historical Phase III trial, Phase III retrospective analysis, retrospective comparative efficacy trial	RCT, randomized controlled trial, randomised controlled trial, clinical randomized trial
関連	5	6
概要	A retrospective Phase III clinical trial evaluates the comparative efficacy and safety of an intervention against a control using data that were collected before the study was designed. Rather than enrolling new patients prospectively, researchers analyze existing records — from registries, hospital databases, or historical trial archives — to address a Phase III-level question: does Treatment A outperform the current standard of care in a large, representative patient population? This design is used when prospective enrollment is infeasible, unethical, or when historical data are sufficiently complete to support a rigorous comparison.	A randomized clinical trial (RCT) is an experimental study design in which participants are randomly assigned to an intervention group or a control group, then followed prospectively to compare outcomes. Random allocation is the defining feature: it distributes known and unknown confounders across groups by chance, making the RCT the strongest individual study design for establishing causal efficacy of a treatment or intervention under controlled conditions.