Novel use of phase angle as a quantitative parameter of general physiological reserve in geriatric patients in long-term care

Novel use of phase angle as a quantitative parameter of general physiological reserve in geriatric patients in long-term care | 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 Novel use of phase angle as a quantitative parameter of general physiological reserve in geriatric patients in long-term care Alejandro Padilla Isassi, Rosalba Maya Hernández, María Elisa Otero Cerdeira, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9204893/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Background Physiological reserve reflects the capacity of the organism to maintain homeostasis under biological stress. Phase angle derived from bioelectrical impedance analysis has been proposed as a potential objective marker of Physiological reserve. Methods An analytical cross-sectional study was conducted in 45 older adults residing in long-term care units at Hospital Español de México (2025). Frailty was assessed with the FRAIL index, sarcopenia using EWGSOP2 criteria, functionality with the Barthel Index, and quality of life with WHOQOL-OLD. Body composition and phase angle were measured by multifrequency bioelectrical impedance (InBody BWA 2.0®). Associations were analyzed using ROC curves and regression models. Results Phase angle (PA) was closely associated with key geriatric domains. Frail participants showed significantly lower PA values (3.1 ± 0.7 vs. 3.8 ± 0.9; p = 0.009), sarcopenic patients presented lower PA (3.1 ± 0.7 vs. 4.1 ± 0.9; p < 0.001). PA demonstrated a strong positive correlation with functional status (r = 0.668; p < 0.001). A moderate positive correlation was observed with quality of life (r = 0.551; p = 0.001). In multivariable analysis, PA was independently associated with age (B = − 0.063; p < 0.001), functionality (B = 0.013; p < 0.001), and frailty (B = − 0.137; p = 0.044). Conclusions The phase angle discriminates and adapts to key geriatric conditions associated with reduced physiological reserve in older adults in long-term care, providing the missing piece of the puzzle and proposing PhA as a novel biomarker of physiological reserve in the geriatric patient. Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 09 May, 2026 Reviews received at journal 08 May, 2026 Reviews received at journal 22 Apr, 2026 Reviewers agreed at journal 21 Apr, 2026 Reviewers agreed at journal 19 Apr, 2026 Reviewers agreed at journal 17 Apr, 2026 Reviewers invited by journal 17 Apr, 2026 Editor assigned by journal 16 Apr, 2026 Editor invited by journal 07 Apr, 2026 Submission checks completed at journal 06 Apr, 2026 First submitted to journal 06 Apr, 2026 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-9204893","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":627774101,"identity":"d44318bb-0112-494d-8be6-104c9dab32d1","order_by":0,"name":"Alejandro Padilla Isassi","email":"data:image/png;base64,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","orcid":"","institution":"Hospital Español","correspondingAuthor":true,"prefix":"","firstName":"Alejandro","middleName":"Padilla","lastName":"Isassi","suffix":""},{"id":627774102,"identity":"cb2e2b0a-9e2e-476c-b48a-5cbae876b80e","order_by":1,"name":"Rosalba Maya Hernández","email":"","orcid":"","institution":"Hospital Español","correspondingAuthor":false,"prefix":"","firstName":"Rosalba","middleName":"Maya","lastName":"Hernández","suffix":""},{"id":627774103,"identity":"37b94a33-da33-4688-859d-94155df7dd26","order_by":2,"name":"María Elisa Otero Cerdeira","email":"","orcid":"","institution":"Hospital Español","correspondingAuthor":false,"prefix":"","firstName":"María","middleName":"Elisa Otero","lastName":"Cerdeira","suffix":""},{"id":627774104,"identity":"f84e4a7c-252b-4de9-9617-c2862d246628","order_by":3,"name":"Ingrid Alejandra Abarca Salinas","email":"","orcid":"","institution":"Hospital Español","correspondingAuthor":false,"prefix":"","firstName":"Ingrid","middleName":"Alejandra Abarca","lastName":"Salinas","suffix":""}],"badges":[],"createdAt":"2026-03-23 23:08:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9204893/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9204893/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107869451,"identity":"f6979415-7476-494d-b01a-f3e0b60b9d63","added_by":"auto","created_at":"2026-04-27 07:37:04","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":514393,"visible":true,"origin":"","legend":"","description":"","filename":"2.ManuscriptCORRECIONES.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9204893/v1_covered_2e31f819-700f-4ba3-888f-40b6d3322c50.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Novel use of phase angle as a quantitative parameter of general physiological reserve in geriatric patients in long-term care","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"bmc-geriatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bgtc","sideBox":"Learn more about [BMC Geriatrics](http://bmcgeriatr.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bgtc/default.aspx","title":"BMC Geriatrics","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-9204893/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9204893/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePhysiological reserve reflects the capacity of the organism to maintain homeostasis under biological stress. Phase angle derived from bioelectrical impedance analysis has been proposed as a potential objective marker of Physiological reserve.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eAn analytical cross-sectional study was conducted in 45 older adults residing in long-term care units at Hospital Espa\u0026ntilde;ol de M\u0026eacute;xico (2025). Frailty was assessed with the FRAIL index, sarcopenia using EWGSOP2 criteria, functionality with the Barthel Index, and quality of life with WHOQOL-OLD. Body composition and phase angle were measured by multifrequency bioelectrical impedance (InBody BWA 2.0\u0026reg;). Associations were analyzed using ROC curves and regression models.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003ePhase angle (PA) was closely associated with key geriatric domains. Frail participants showed significantly lower PA values (3.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7 vs. 3.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9; p\u0026thinsp;=\u0026thinsp;0.009), sarcopenic patients presented lower PA (3.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7 vs. 4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). PA demonstrated a strong positive correlation with functional status (r\u0026thinsp;=\u0026thinsp;0.668; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). A moderate positive correlation was observed with quality of life (r\u0026thinsp;=\u0026thinsp;0.551; p\u0026thinsp;=\u0026thinsp;0.001). In multivariable analysis, PA was independently associated with age (B\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.063; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), functionality (B\u0026thinsp;=\u0026thinsp;0.013; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and frailty (B\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.137; p\u0026thinsp;=\u0026thinsp;0.044).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThe phase angle discriminates and adapts to key geriatric conditions associated with reduced physiological reserve in older adults in long-term care, providing the missing piece of the puzzle and proposing PhA as a novel biomarker of physiological reserve in the geriatric patient.\u003c/p\u003e","manuscriptTitle":"Novel use of phase angle as a quantitative parameter of general physiological reserve in geriatric patients in long-term care","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-24 17:29:10","doi":"10.21203/rs.3.rs-9204893/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-09T17:29:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-09T01:52:31+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-22T12:59:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"90542012403829091365942775015963163607","date":"2026-04-21T07:00:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"260449089985166360903995398548940739856","date":"2026-04-19T09:07:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"101272747547731678080412854365315717574","date":"2026-04-17T13:00:37+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-17T04:30:20+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-16T04:57:09+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-07T04:09:26+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-06T17:48:52+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Geriatrics","date":"2026-04-06T16:48:50+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-geriatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bgtc","sideBox":"Learn more about [BMC Geriatrics](http://bmcgeriatr.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bgtc/default.aspx","title":"BMC Geriatrics","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"073382ac-f8a3-4b8f-918a-44350aca59bb","owner":[],"postedDate":"April 24th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-09T17:29:35+00:00","index":76,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-09T01:52:31+00:00","index":75,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-24T17:29:11+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-24 17:29:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9204893","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9204893","identity":"rs-9204893","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}