방법 비교

	후향적 3상 임상시험	2상 임상시험
분야	역학	역학
계열	Process / pipeline	Process / pipeline
기원 연도	Late 20th century (ICH E8 1997; widespread retrospective Phase III use from 1990s onward)	1960s–1970s (formalised in US federal drug regulation)
창시자	Regulatory framework codified by ICH E8/E9 (1997–1998); retrospective application developed through post-marketing and registry practice	U.S. Food and Drug Administration / ICH E8 guidelines (institutionalised framework)
유형	Retrospective comparative clinical study	Interventional clinical study design
원전	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: 978-3319185392
별칭	retrospective Phase III study, historical Phase III trial, Phase III retrospective analysis, retrospective comparative efficacy trial	Phase 2 trial, Phase II study, early efficacy trial, proof-of-concept trial
관련	5	6
요약	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 Phase II clinical trial is the second stage in the drug or intervention development pipeline, conducted after Phase I safety testing. Its primary goal is to assess whether the intervention shows preliminary efficacy signals in a relevant patient population at the dose established in Phase I, while continuing to characterise the safety and tolerability profile. Phase II trials are generally smaller than Phase III confirmatory trials and serve as critical go/no-go decision points before large-scale investment.