手法を比較

	リスク調整済み第IV相試験	逆確率重み付け法 (IPW / IPTW)
分野	疫学	因果推論
系統	Process / pipeline	Regression model
提唱年	1990s–2000s (formalized with ICH E2E and EMA PASS guidelines)	2000
提唱者	Regulatory and pharmacoepidemiology community (ICH, EMA, FDA frameworks)	Robins, Hernán & Brumback
種類	Observational / quasi-experimental clinical study design	Causal inference weighting estimator
原典	Strom, B. L. (Ed.). (2005). Pharmacoepidemiology (4th ed.). John Wiley & Sons. ISBN: 978-0470863107	Robins, J. M., Hernán, M. A., & Brumback, B. (2000). Marginal Structural Models and Causal Inference in Epidemiology. Epidemiology, 11(5), 550-560.
別名	risk-adjusted post-marketing surveillance study, adjusted Phase IV trial, risk-stratified post-authorization study, PASS with risk adjustment	IPW, IPTW, inverse probability of treatment weighting, marginal structural model weighting
関連	3	5
概要	A risk-adjusted Phase IV study is an observational or semi-experimental post-marketing study conducted after a drug or device has received regulatory approval. It uses statistical risk-adjustment techniques — such as propensity score matching, inverse probability weighting, or multivariable regression — to control for confounding by indication and baseline patient differences, thereby producing more credible safety, effectiveness, and utilization estimates than unadjusted real-world analyses.	Inverse Probability Weighting is a causal-inference method that assigns each observation a weight equal to the inverse of its probability of receiving the treatment it actually received. Introduced by Robins, Hernán and Brumback (2000) for marginal structural models, it builds a pseudo-population in which treatment is independent of measured confounders, balancing selection bias.