Hardening Legacy Patient Identifiers Against Transcription Errors: A Table-Free Verhoeff Formulation

Zero-Downtime Hardening of Legacy Patient Identifiers Against Transcription Errors: A Table-Free Verhoeff Formulation | 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 Zero-Downtime Hardening of Legacy Patient Identifiers Against Transcription Errors: A Table-Free Verhoeff Formulation Csaba Balogh This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9370549/v2 This work is licensed under a CC BY 4.0 License Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Abstract Background . Patient identification in health registries relies on decimal identifiers whose integrity checks were designed for isolated systems. In a densely allocated namespace, an undetected transcription error may silently retrieve another person’s clinical record. Commutative check-digit schemes are structurally blind to certain adjacent transpositions; the Hungarian Social Security Number serves as our case study. Methods . We formalise the identified blind spot and propose a backward-compatible supplementary fold-check digit derived from a non-commutative fold over the ten-element dihedral group. We give a cycle-conjugate arithmetic realisation of the Verhoeff permutation that replaces the standard permutation and multiplication tables with two 10-element vectors, modulo-5 and modulo-10 arithmetic, and a single exclusive-or operation. To our knowledge, this is the first table-free realisation suitable for safety-critical audit. Results . Under the legacy check, 20 of the 100 ordered digit pairs are invisible to the checksum, yielding an approximately 10% upper bound on identity-altering yet formally valid errors. The proposed fold-check digit deterministically eliminates this gap for adjacent transpositions and single-digit substitutions. Monte Carlo experiments with 8,000 and 150,000 trials per configuration confirm 100% rejection of both error types. Conclusions . The hardened protocol offers minimal-footprint hardening layer: no change to the primary identifier, backward compatibility, and a deterministic guarantee against adjacent transpositions and single-digit substitutions. The cycle-conjugate formulation reduces the classical Verhoeff table footprint by roughly 90%, and the framework generalises to any legacy decimal identifier with a commutative check. The approach strengthens the identifier infrastructure on which clinical decision support and health information exchange rely, closing a foundational patient-safety gap. patient identification check digit transposition error Verhoeff algorithm health information exchange patient safety Full Text Additional Declarations The authors declare no competing interests. Supplementary Files supplementary.pdf Supplementary Material graphicalabstract.png Geographic Abstract Cite Share Download PDF Status: Posted Version 2 posted You are reading this latest preprint version Show more versions 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-9370549","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":623990431,"identity":"10f07c84-739d-4eab-9fae-d8afa9b160e3","order_by":0,"name":"Csaba Balogh","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABC0lEQVRIie3RMUvDQBTA8XdkyHKQ9Y5Q7itcObAE+mESAplSF5dMchK4LoWu+RgdHRMCThFxy+DQQ3ASiYhQcTGhgnS4qFuh95/u8e43PQCb7Qjj4EhAcnhigA5C73tRjhD0Q1ABIZX/Ig7+C5m51ZV+vwbGlrfV2zxLiAfu/SOGh0gaSLCKcjFpYLppzmM/bVJCJb4QGJ6MhJeR8qmCkEPK/YXKLnmJE1pAbSZ3ek/Y+ll8Biojv5M2UvS1J9CmZz5SaU/cG9KNkKDQuUCKTDftSxKsmoTQHDu847UwkZkXV/pDzRlbL+p2l8XEc5d6G2b1xESG+nOQg5EP9xoN7Q5ndzv+32az2U6tL+p+W1vRRMjXAAAAAElFTkSuQmCC","orcid":"","institution":"National Directorate General for Hospitals, HUNGARY","correspondingAuthor":true,"prefix":"","firstName":"Csaba","middleName":"","lastName":"Balogh","suffix":""}],"badges":[],"createdAt":"2026-04-09 15:38:31","currentVersionCode":2,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-9370549/v2","doiUrl":"https://doi.org/10.21203/rs.3.rs-9370549/v2","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108181194,"identity":"2ae8bade-01bd-4fb8-8cf4-d2b291f86d59","added_by":"auto","created_at":"2026-04-30 08:58:21","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":200669,"visible":true,"origin":"","legend":"","description":"","filename":"main.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9370549/v2_covered_33d52f56-4695-4470-a1cd-f7f291284df3.pdf"},{"id":108042620,"identity":"5a61e801-3d99-4aae-80d7-9237eecaf776","added_by":"auto","created_at":"2026-04-28 18:29:26","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":195749,"visible":true,"origin":"","legend":"\u003cp\u003eSupplementary Material\u003c/p\u003e","description":"","filename":"supplementary.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9370549/v2/99d28befeb8b35d4fc348fd4.pdf"},{"id":108042621,"identity":"1a7035b5-91e8-4eb1-9591-242348571619","added_by":"auto","created_at":"2026-04-28 18:29:26","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":14357,"visible":true,"origin":"","legend":"\u003cp\u003eGeographic Abstract\u003c/p\u003e","description":"","filename":"graphicalabstract.png","url":"https://assets-eu.researchsquare.com/files/rs-9370549/v2/52b6c6f2f5c61e0950f0841d.png"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eZero-Downtime Hardening of Legacy Patient Identifiers Against Transcription Errors: A Table-Free Verhoeff Formulation\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"patient identification, check digit, transposition error, Verhoeff algorithm, health information exchange, patient safety","lastPublishedDoi":"10.21203/rs.3.rs-9370549/v2","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9370549/v2","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e. Patient identification in health registries relies on decimal identifiers whose integrity checks were designed for isolated systems. In a densely allocated namespace, an undetected transcription error may silently retrieve another person’s clinical record. Commutative check-digit schemes are structurally blind to certain adjacent transpositions; the Hungarian Social Security Number serves as our case study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e. We formalise the identified blind spot and propose a backward-compatible supplementary fold-check digit derived from a non-commutative fold over the ten-element dihedral group. We give a cycle-conjugate arithmetic realisation of the Verhoeff permutation that replaces the standard permutation and multiplication tables with two 10-element vectors, modulo-5 and modulo-10 arithmetic, and a single exclusive-or operation. To our knowledge, this is the first table-free realisation suitable for safety-critical audit.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e. Under the legacy check, 20 of the 100 ordered digit pairs are invisible to the checksum, yielding an approximately 10% upper bound on identity-altering yet formally valid errors. The proposed fold-check digit deterministically eliminates this gap for adjacent transpositions and single-digit substitutions. Monte Carlo experiments with 8,000 and 150,000 trials per configuration confirm 100% rejection of both error types. \u003cstrong\u003eConclusions\u003c/strong\u003e. The hardened protocol offers minimal-footprint hardening layer: no change to the primary identifier, backward compatibility, and a deterministic guarantee against adjacent transpositions and single-digit substitutions. The cycle-conjugate formulation reduces the classical Verhoeff table footprint by roughly 90%, and the framework generalises to any legacy decimal identifier with a commutative check. The approach strengthens the identifier infrastructure on which clinical decision support and health information exchange rely, closing a foundational patient-safety gap.\u003c/p\u003e","manuscriptTitle":"Zero-Downtime Hardening of Legacy Patient Identifiers Against Transcription Errors: A Table-Free Verhoeff Formulation","msid":"","msnumber":"","nonDraftVersions":[{"code":2,"date":"2026-04-28 18:29:22","doi":"10.21203/rs.3.rs-9370549/v2","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}},{"code":1,"date":"2026-04-16 03:50:01","doi":"10.21203/rs.3.rs-9370549/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6dc1692e-234b-4bc5-819e-b8e5b7a02040","owner":[],"postedDate":"April 28th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-16T03:50:04+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-28 18:29:22","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v2","identity":"rs-9370549","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9370549","identity":"rs-9370549","version":["v2"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}