เปรียบเทียบวิธี

	การศึกษาเฟส 4	การศึกษาแบบกลุ่ม (Cohort Study)
สาขาวิชา	ระบาดวิทยา	ระบาดวิทยา
ตระกูล	Process / pipeline	Process / pipeline
ปีกำเนิด	Formalised 1970s–1990s (ICH E3 guideline 1994)	Mid-20th century (formal epidemiological design codified ~1950s)
ผู้ริเริ่ม	Regulatory agencies and pharmaceutical industry (ICH, FDA, EMA frameworks)	Doll & Hill (British Doctors Study, 1951); Snow (cholera, 1854)
ประเภท	Post-marketing observational or interventional study	Observational longitudinal study design
แหล่งต้นตำรับ	International Conference on Harmonisation (ICH). (1994). ICH Harmonised Tripartite Guideline: Structure and Content of Clinical Study Reports E3. ICH Secretariat.	Rothman, K. J., Greenland, S., & Lash, T. L. (2008). Modern Epidemiology (3rd ed.). Lippincott Williams & Wilkins. ISBN: 978-0781755641
ชื่อเรียกอื่น	post-marketing surveillance study, post-approval study, Phase 4 study, PMS study	longitudinal study, follow-up study, panel study, incidence study
ที่เกี่ยวข้อง	5	6
สรุป	A Phase IV study is a post-marketing surveillance study conducted after a drug, device, or intervention has received regulatory approval. Its primary purpose is to monitor long-term safety, detect rare adverse events, assess effectiveness in routine clinical practice, and explore new indications or populations not adequately represented in earlier trials. Phase IV evidence accumulates continuously throughout a product's commercial life.	A cohort study assembles a group of individuals who share a common starting point — typically freedom from the outcome of interest — and follows them over time to observe who develops the outcome. By comparing incidence rates between exposed and unexposed subgroups, researchers can estimate relative risk and absolute risk differences. Cohort studies are the gold-standard observational design for measuring disease incidence and establishing temporal relationships between exposure and outcome.