방법 비교

	전향적 사례 시리즈	후향적 증례 시리즈
분야	역학	역학
계열	Process / pipeline	Process / pipeline
기원 연도	Late 19th century onward; formalized in modern clinical epidemiology by the 1970s–1980s	Long-standing practice; codified in EBM frameworks during 1990s–2000s
창시자	Evolved from clinical case reporting traditions in 19th–20th century medicine	Clinical medicine tradition (no single originator); formalized in evidence-based medicine literature
유형	Observational study design	Observational descriptive study design
원전	Meinert, C. L. (1996). Clinical Trials: Design, Conduct, and Analysis. Oxford University Press. ISBN: 978-0195035681	Kooistra, B., Dijkman, B., Einhorn, T. A., & Bhandari, M. (2009). How to design a good case series. Journal of Bone and Joint Surgery, 91(Suppl 3), 21–26.
별칭	prospective case series study, forward-looking case series, prospective uncontrolled study, prospective observational case series	retrospective case series, chart review case series, historical case series, medical records case series
관련	5	4
요약	A prospective case series is an observational study design in which a group of patients with a particular condition, exposure, or intervention is identified in advance and followed forward in time according to a pre-specified protocol. Data on outcomes, adverse events, and clinical course are collected as they occur, yielding higher data quality and temporal clarity than retrospective designs. No control group is included, so causal inference is limited, but the design is valuable for characterizing natural disease history, early safety signals, and feasibility of new interventions.	A retrospective case series is an observational study that systematically describes the clinical features, treatments, and outcomes of a defined group of patients by examining pre-existing medical records or administrative data. It looks backward in time — data have already been recorded before the study begins. With no control group, no randomization, and no prospective follow-up, it sits near the base of the evidence hierarchy but remains one of the most practical and frequently published study designs in clinical medicine.