방법 비교

	회고적 2상 임상시험	2상 임상시험
분야	역학	역학
계열	Process / pipeline	Process / pipeline
기원 연도	1980s–1990s (with growth in oncology retrospective analyses)	1960s–1970s (formalised in US federal drug regulation)
창시자	Adapted from standard Phase II trial methodology; retrospective variant formalized in oncology practice	U.S. Food and Drug Administration / ICH E8 guidelines (institutionalised framework)
유형	Observational retrospective study	Interventional clinical study design
원전	Simon, R. (1989). Optimal two-stage designs for phase II clinical trials. Controlled Clinical Trials, 10(1), 1–10.	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 II study, historical Phase II analysis, retrospective efficacy study, Phase II retrospective analysis	Phase 2 trial, Phase II study, early efficacy trial, proof-of-concept trial
관련	5	6
요약	A retrospective Phase II clinical trial evaluates a treatment's preliminary efficacy and safety signals using existing archival data — medical records, registries, or electronic health records — rather than prospectively enrolling new patients. It mirrors the objectives of a standard Phase II trial (estimating response rate, tolerability, and early efficacy) but does so by looking backward at patients who have already received the intervention, making it faster and less costly than a prospective design.	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.