LINE ZERO: Redefining the Start of Healthcare—Self-Observation as a Pre-Clinical Level of Care

Background: Healthcare systems are organized around traditional levels of care—primary, secondary, tertiary, and quaternary—activated only when a patient enters the formal system. This downstream architecture is effective but reactive. Translational medicine typically moves from bench to bedside. Here we propose a reverse translational step: a patient-led, pre-clinical level of care, upstream of the formal system. Objective: To introduce LINE ZERO, a concept of structured self-observation situated upstream of clinical care, grounded in a targeted literature review, and to illustrate its feasibility through a documented self-observation. Concept: Drawing on a targeted literature review of modern upstream approaches—including P4/P5 medicine, cybernetics, digital twins, and One Health—LINE ZERO is proposed as a formal, pre-clinical level of care, extending the traditional levels-of-care model upstream. It comprises three components—self-care practices, self-monitoring, and self-management—forming a voluntary feedback loop—observe, interpret, adjust—at the dynamic heart of LINE ZERO. Its design is generic, modular, low-cost, and accessible without medical supervision, while encouraging consultation in case of doubt. Proof-of-Concept: The concept was illustrated through an 11-month longitudinal self-observation conducted by the author on himself. Self-care practices included breathing exercises, light therapy, music therapy, gentle stretching, and moderate dietary changes; self-monitoring covered blood pressure, deep sleep, and capillary glucose using commercially available devices. The observation demonstrated the feasibility of tracking physiological events in real time and documenting meaningful changes, without clinical, diagnostic, or therapeutic claim. Conclusion: LINE ZERO extends the traditional care model by adding a pre-clinical, self-management space upstream of the formal system. It aligns with P4/P5 medicine and represents a reverse translational contribution—from self-observation to a conceptual model applicable to health systems. It invites researchers, clinicians, and decision-makers to consider structured self-observation as a component of a sustainable healthcare future.