{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T11:29:29Z","timestamp":1787052569622,"version":"build-2736575974"},"reference-count":18,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T00:00:00Z","timestamp":1787011200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T00:00:00Z","timestamp":1787011200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"name":"Universit\u00e4tsklinikum Freiburg"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Neurol. Res. Pract."],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background and Purpose<\/jats:title>\n                    <jats:p>Direct oral anticoagulants (DOAC) complicate therapeutic decision-making, as rapid assessment of anticoagulant activity is critical in emergency patients, particularly in acute ischemic stroke (AIS). The administration of systemic thrombolysis (IVT) in anti-coagulated patients requires careful risk\u2013benefit evaluation, given the potential for hemorrhagic complications. Substance-specific DOAC plasma level measurements are often unavailable outside tertiary centers. This study evaluated whether widely available heparin-calibrated anti-factor Xa (anti-Xa) activity can reliably estimate clinically relevant DOAC levels and support urgent clinical decision-making.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>This retrospective single-center study (2015\u20132023) analyzed 969 patients treated with apixaban, rivaroxaban, or edoxaban. All patients had parallel measurements of anti-Xa activity and specific DOAC levels. Correlations were assessed using Spearman\u2019s coefficient. Receiver operating characteristic (ROC) analyses were performed to derive anti-Xa cut-off values corresponding to DOAC concentrations of 30, 50, and 100 ng\/mL.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Anti-Xa activity strongly correlated with DOAC plasma levels for all substances (Spearman\u2019s \u03c1\u2009\u2248\u20090.95\u20130.96). ROC analyses demonstrated excellent diagnostic accuracy, with areas under the curve\u2009\u2265\u20090.97 for all evaluated thresholds. Similar anti-Xa cut-offs were observed for apixaban and rivaroxaban, whereas these were lower for edoxaban. For all DOACs combined, anti-Xa cut-offs of approximately 0.36U\/mL, 0.56U\/mL, and 1.19U\/mL corresponded to DOAC levels of 30, 50, and 100ng\/mL, respectively, with high sensitivity and specificity.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Heparin-calibrated anti-Xa activity is a reliable surrogate marker for clinically relevant DOAC levels. Defined anti-Xa cut-offs are highly specific and sensitive and enable rapid and standardized assessment of anticoagulant activity in this cohort.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1186\/s42466-026-00524-1","type":"journal-article","created":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T10:56:32Z","timestamp":1787050592000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Heparin-calibrated anti-factor Xa activity as a surrogate marker for direct oral anticoagulant levels in acute stroke care: a large observational single-center study"],"prefix":"10.1186","volume":"8","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9400-9625","authenticated-orcid":false,"given":"Martin","family":"B\u00fcchsel","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Katharina","family":"Lisko","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hanna","family":"G\u00f6lz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3372-2651","authenticated-orcid":false,"given":"J\u00fcrgen","family":"Bardutzky","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4310-3432","authenticated-orcid":false,"given":"Heinz","family":"Wiendl","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sa\u00fal Beltr\u00e1n","family":"Felipa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4078-778X","authenticated-orcid":false,"given":"Johann","family":"Lambeck","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,8,18]]},"reference":[{"issue":"9921","key":"524_CR1","doi-asserted-by":"publisher","first-page":"955","DOI":"10.1016\/S0140-6736(13)62343-0","volume":"383","author":"CT Ruff","year":"2014","unstructured":"Ruff, C. T., Giugliano, R. P., Braunwald, E., Hoffman, E. B., Deenadayalu, N., Ezekowitz, M. D., et al. (2014). Comparison of the efficacy and safety of new oral anticoagulants with warfarin in patients with atrial fibrillation: a meta-analysis of randomised trials. Lancet, 383(9921), 955\u2013962. https:\/\/doi.org\/10.1016\/S0140-6736(13)62343-0","journal-title":"Lancet"},{"issue":"8","key":"524_CR2","doi-asserted-by":"publisher","first-page":"770","DOI":"10.1055\/a-2261-1811","volume":"124","author":"J Harenberg","year":"2024","unstructured":"Harenberg, J., Gosselin, R. C., Cuker, A., Becattini, C., Pabinger, I., Poli, S., et al. (2024). Algorithm for Rapid Exclusion of Clinically Relevant Plasma Levels of Direct Oral Anticoagulants in Patients Using the DOAC Dipstick: An Expert Consensus Paper. 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The study was approved by the Ethics Committee of the University Hospital in Freiburg, Germany (IRB Nr. 24-1081-S1-retro).","order":1,"name":"Ethics","label":"Ethics approval and consent to participate","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"No identifiable patient information is provided in the manuscript or figures.","order":2,"name":"Ethics","label":"Consent to publish","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"HW reports the following: He receives honoraria for acting as a member of Scientific Advisory Boards from Alexion, Argenx, Biocryst, Bristol Myers Squibb, Cellerys, Galapagos, Janssen, Merck, Novartis, Sandoz-Hexal, uniQure biopharma B.V. He receives speaker honoraria and travel support from Alexion, AOCN, AstraZeneca, Biogen, BGP Products Operations GmbH, Bristol Myers Squibb, CEMCAT, EPG Health\/Medthority, Genzyme, Kohlhammer, Merck, MS at the Limits, Neurodiem, NMSS, Novartis, Ology, Roche, Sanofi, Springer, Streamed up, TEVA, Uvet, WebMD Global. He is acting as a paid consultant for Alexion, Argenx, Argobio, Bristol Myers Squibb, Dianthus, EMD Serono, Fondazione Cariplo, Idorsia, Immunic, Immunovant, INmune Bio_Syneos Health, Janssen, LTS, Lundbeck, Merck, Muna Therapeutics, Myrobalan Therapeutics, Novartis, PSL Group, Red Nucleus, Roche, Samsung, Sangamo, Sanofi, Swiss Multiple Sclerosis Society, Teladochealth, Toleranzia, UCB, Viatris. His research is funded by the Deutsche Forschungsgemeinschaft (DFG), Deutsche Myasthenie Gesellschaft e.V., European Union, Alexion, Amicus Therapeutics Inc., Argenx, Biogen, CSL Behring, F. Hoffmann - La Roche, Genzyme, Merck KgaA, Novartis, Roche, UCB Biopharma. All other authors declare that they have no competing interests.","order":3,"name":"Ethics","label":"Competing interests","group":{"name":"EthicsHeading","label":"Declarations"}}],"article-number":"67"}}