Lifecycle Coherence as a Criterion of Medical Validity Why Initial Efficacy Is Insufficient for Real-World Therapeutic Reliability

Background: Medical validation and regulatory approval rely largely on evidence from controlled trial conditions and short-to-medium-term endpoints. This paradigm has produced major advances but tacitly assumes that interventions demonstrating benefit at initiation retain clinical validity across long-term real-world use. Aim: To introduce and operationalize a lifecycle-level criterion of medical validity that better aligns evaluation with longitudinal clinical reality. Argument: Downstream instability-including discontinuation syndromes, polypharmacy cascades, diminishing benefit, delayed harms, and revision trajectories-suggests that some interventions fail not at initiation but across their operational lifespan. These outcomes are frequently managed as downstream clinical issues rather than interpreted as constraints on validity. Proposal: We define lifecycle coherence as an intervention's capacity to maintain (i) functional integrity, (ii) proportional benefit, and (iii) system compatibility across initiation, continuation, adaptation, and withdrawal/embedding under real-world conditions. We propose a structured profile (Lifecycle Coherence Index; LCI) to report phase-specific performance. Methods (illustrative): We conduct a falsification-oriented desk review using publicly available registry and meta-analytic sources (accessed December 2025) to test whether the framework can classify lifecycle-coherent interventions as well as identify lifecycle fragility. Conclusions: By reframing medical validity as survivable coherence under consequence rather than peak performance under control, lifecycle coherence offers a unifying lens for well-recognized clinical patterns that remain structurally unintegrated in evaluative systems. The framework has implications for clinical judgment, governance, informed consent, and the design of validation systems that better reflect how treatments behave over time.