Flawed design and selection bias in critical care randomized controlled trials (RCTs): the patient safety risk of the "RCT mimic".

Over three decades, randomized controlled trials (RCTs) for critical care syndromes such as acute respiratory distress syndrome (ARDS), sepsis, and community acquired pneumonia (CAP) have repeatedly produced non-reproducible results, at times leading to high-impact reversals of global protocols when later studies revealed harm. These trials enroll patients using expert-derived threshold sets intended to define the syndrome. This analytic review presents the first historical and formal methodological review and mathematical analysis of such RCT using causal symbolic modeling (cSM), directed acyclic graphs (DAGs), and do-calculus. The review includes landmark publications, task-force threshold sets, and case examples, including the 2025 REMAP-CAP corticosteroid domain, to model the causal structure of standard RCTs applied to threshold-defined syndromes. PubMed searches and ChatGPT were used to assist in this process. The historical inquiry uncovered that the critical care syndromes of ARDS and sepsis are guessed synthetic constructs, devised in the twentieth century by Thomas Petty and Roger Bone as heuristic groupings of diverse but similar appearing diseases. However a much more striking discovery was that Petty and Bone introduced a streamlined variant of the Bradford Hill RCT method, here termed the "Petty-Bone RCT', which conditions enrollment on a triage threshold set that functions as a cohort-level collider. This design yields results valid only for the unstable mixture of diseases enrolled. The "Petty-Bone RCT" preserves the outward form of a randomized trial but lacks the causal structure needed for transportability, making it an RCT mimic. The cSM analysis in this review shows that while potentially internally valid, such trials cannot produce reliable treatment protocols and often cause harm. These findings compel the abandonment of the Petty-Bone RCT framework, the integration of cSM into the Consolidated Standards of Reporting Trials (CONSORT), and prioritizing mechanistically grounded, investigator-led designs in critical care research. These provocative discoveries indicate that not one more patient, not one more investigator, not one more grant should be sacrificed to the next iteration of a Petty and Bone's synthetic syndrome RCT.