{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,8]],"date-time":"2026-07-08T05:39:01Z","timestamp":1783489141315,"version":"3.55.0"},"reference-count":34,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2025,4,15]],"date-time":"2025-04-15T00:00:00Z","timestamp":1744675200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100008627","name":"Global Affairs Canada","doi-asserted-by":"publisher","award":["CA-3-D000920001"],"award-info":[{"award-number":["CA-3-D000920001"]}],"id":[{"id":"10.13039\/501100008627","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100008627","name":"Global Affairs Canada","doi-asserted-by":"publisher","award":["72044020FA00001"],"award-info":[{"award-number":["72044020FA00001"]}],"id":[{"id":"10.13039\/501100008627","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000200","name":"United States Agency for International Development","doi-asserted-by":"publisher","award":["CA-3-D000920001"],"award-info":[{"award-number":["CA-3-D000920001"]}],"id":[{"id":"10.13039\/100000200","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000200","name":"United States Agency for International Development","doi-asserted-by":"publisher","award":["72044020FA00001"],"award-info":[{"award-number":["72044020FA00001"]}],"id":[{"id":"10.13039\/100000200","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background: The Xpert MTB\/RIF Ultra assay (Ultra) is a second-generation molecular diagnostic test for tuberculosis (TB). The \u201cTrace Call\u201d result was added as a semi-quantitative category for extremely low bacillary loads. The prevalence and interpretation of Trace Call results remains insufficiently elucidated in the context of community-based active case finding (ACF). Methods: We organized 56 days of mobile chest X-ray (CXR) screening events in Ho Chi Minh City, Viet Nam, between October 2020 and March 2021. Participants were screened verbally and by CXR and tested by Ultra, if eligible. Persons with a Trace Call were re-tested on Ultra per national guidelines. qXRv3 computer-aided detection software was used for post hoc quality control of CXR interpretation. We calculated descriptive statistics and fitted mixed-effect multivariate regression models to identify factors associated with Trace Call results and confirmatory diagnosis. Results: A total of 16,698 people were screened by CXR to detect 185 Ultra-positive participants, including 142 persons with a confirmed TB diagnosis. Among Ultra-positive participants, 38.4% (71\/185) had Trace Call results. Of these, 85.9% (61\/71) were re-tested, and 45.9% (28\/61) were bacteriologically-confirmed, comprising 19.7% (28\/142) of the final number of confirmed diagnoses. Having a low qXR abnormality score (&lt;0.5) (aOR = 4.97; 95%CI: [1.88, 13.14]; p = 0.001) and a history of TB within 5 recent years (aOR = 3.53; 95%CI: [1.69, 7.35]; p = 0.001) were associated with an initial Trace Call. Conclusions: The Trace Call can improve ACF detection, particularly in earlier stages of disease with limited pulmonary deterioration. However, participants with a history of TB had higher rates of Trace Call, reinforcing the need to interpret test results in this group with caution.<\/jats:p>","DOI":"10.3390\/diagnostics15081006","type":"journal-article","created":{"date-parts":[[2025,4,15]],"date-time":"2025-04-15T09:41:11Z","timestamp":1744710071000},"page":"1006","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Prevalence of Xpert MTB\/RIF Ultra Trace Call Results and Associated Risk Factors During Active Tuberculosis Case Finding in Viet Nam: A Programmatic Evaluation"],"prefix":"10.3390","volume":"15","author":[{"given":"Luong","family":"Van Dinh","sequence":"first","affiliation":[{"name":"National Lung Hospital, Ha Noi 100000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Khoa Tu","family":"Tran","sequence":"additional","affiliation":[{"name":"Friends for International TB Relief, Ha Noi 100000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew James","family":"Codlin","sequence":"additional","affiliation":[{"name":"Friends for International TB Relief, Ha Noi 100000, Vietnam"},{"name":"Department of Global Public Health, WHO Collaboration Centre on Tuberculosis and Social Medicine, Karolinska Institutet, Solna, 17176 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5937-6286","authenticated-orcid":false,"given":"Luan Nguyen Quang","family":"Vo","sequence":"additional","affiliation":[{"name":"Friends for International TB Relief, Ha Noi 100000, Vietnam"},{"name":"Department of Global Public Health, WHO Collaboration Centre on Tuberculosis and Social Medicine, Karolinska Institutet, Solna, 17176 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nga Thuy Thi","family":"Nguyen","sequence":"additional","affiliation":[{"name":"Friends for International TB Relief, Ha Noi 100000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lan Phuong","family":"Nguyen","sequence":"additional","affiliation":[{"name":"IRD VN Social Enterprise Ltd., Ho Chi Minh City 700000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0716-3342","authenticated-orcid":false,"given":"Rachel","family":"Forse","sequence":"additional","affiliation":[{"name":"Friends for International TB Relief, Ha Noi 100000, Vietnam"},{"name":"Department of Global Public Health, WHO Collaboration Centre on Tuberculosis and Social Medicine, Karolinska Institutet, Solna, 17176 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5541-8322","authenticated-orcid":false,"given":"Han Thi","family":"Nguyen","sequence":"additional","affiliation":[{"name":"Friends for International TB Relief, Ha Noi 100000, Vietnam"},{"name":"Department of Global Public Health, WHO Collaboration Centre on Tuberculosis and Social Medicine, Karolinska Institutet, Solna, 17176 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thi Minh Ha","family":"Dang","sequence":"additional","affiliation":[{"name":"Pham Ngoc Thach Hospital, Ho Chi Minh City 700000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lan Huu","family":"Nguyen","sequence":"additional","affiliation":[{"name":"Pham Ngoc Thach Hospital, Ho Chi Minh City 700000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hoa Binh","family":"Nguyen","sequence":"additional","affiliation":[{"name":"National Lung Hospital, Ha Noi 100000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4885-940X","authenticated-orcid":false,"given":"Jacob","family":"Creswell","sequence":"additional","affiliation":[{"name":"Stop TB Partnership, 1218 Geneva, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,15]]},"reference":[{"key":"ref_1","unstructured":"World Health Organization (2024). 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