From Population Norms to Personal Baselines: A Paradigm Shift in Functional Health Surveillance

From Population Norms to Personal Baselines: A Paradigm Shift in Functional Health Surveillance | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article From Population Norms to Personal Baselines: A Paradigm Shift in Functional Health Surveillance Swapan Samanta, M. Roychoudhury This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8974103/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Modern screening programmes compare individuals to population averages—a practice inherited from the statistical conventions of 20th-century epidemiology. Yet biological variation within a person over time is typically two to four times smaller than variation between individuals. 1 A clinically dangerous change in one person may therefore be entirely invisible when assessed against population reference ranges. We present a decade of prospective evidence from 560 individuals demonstrating that monitoring personal gait-signature deviation—the Personal Deviation Index (PDI)—dramatically outperforms population-norm comparison for predicting cerebrovascular disease (AUC 0.87 vs 0.68; p < 0.001). We argue that this finding reflects a general biological principle with implications far beyond gait analysis: the future of screening lies in comparing each person to themselves, not to everyone else. personal baseline biological variation gait signature Personal Deviation Index precision screening preventive medicine population norms reference change value Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8974103","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":601088778,"identity":"d972b706-b24a-476c-b9f3-4c270df14b29","order_by":0,"name":"Swapan Samanta","email":"data:image/png;base64,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","orcid":"","institution":"EKO X-Ray Centre for Advanced Cardiology","correspondingAuthor":true,"prefix":"","firstName":"Swapan","middleName":"","lastName":"Samanta","suffix":""},{"id":601088779,"identity":"b4c0c400-0d0f-42fa-81e0-25fb2337dbc2","order_by":1,"name":"M. 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