Evidence-Selective Medicine: A Six-Level Model of Institutional Bias in Clinical Medicine

In 2002, headlines warned that hormone therapy increased breast cancer risk by 26%. Within months, millions of women discontinued treatment. Yet the finding was statistically nonsignificant when analyzed per the study's own protocol. How did a marginal, nonsignificant result become decisive institutional policy—and why does that policy persist two decades later despite consistent, contradictory evidence? Evidence-based medicine (EBM) aspires to rank knowledge by methodological quality. Yet in practice, the application of rigor often depends on whether findings support dominant paradigms. Menopausal hormone therapy (MHT) is used as an ideal case study: it involves both preventive and therapeutic uses, strong RCT and observational evidence, and decades of institutional guidance. This article introduces evidence-selective medicine—a systematic asymmetry in how evidence is evaluated depending on alignment with institutional narratives. A six-level model is presented, explaining how selective evaluation of evidence evolves from technical bias to institutional preservation. This analysis builds on a growing literature recognizing that evidence-based medicine itself has undergone epistemic drift. Critics such as Ioannidis, Greenhalgh, and Chalmers have shown that the very frameworks intended to protect against bias can become structurally biased when alignment prioritizes industrial, regulatory, or professional interests.