Proportions of Xpert MTB/RIF Ultra 'trace' results vary widely among different populations with presumptive TB.

<sec><title>BACKGROUND</title>Microbiological confirmation of(MTB) with XpertMTB/RIF Ultra is recommended, but the interpretation of a 'trace' result is uncertain. We aimed to determine the proportion of Xpert Ultra-positive results reported as 'trace' and how the 'trace' result informed patient care.</sec><sec><title>METHODS</title>We searched MEDLINE OVID, EMBASE, PubMed, Scopus, and Web of Science. All studies until September 2023 that reported Xpert Ultra 'trace' and non-trace MTB-positive results were included for analysis. The Joanna Briggs Institute tool evaluated methodological quality.</sec><sec><title>RESULTS</title>The review identified 62 studies conducted across 23 countries with 124,749 participants. The proportions of 'trace' varied widely from 3.1% to 80%; this proportion was 30% or higher in 26 (42%) studies. Higher 'trace' proportions were reported among children and in extrapulmonary samples. MTB culture, when done, was positive in 23.5% of 'trace' compared to 60.5% of non-trace positive results. Data on treatment decisions for those with 'trace' results were usually not reported, although some who were not treated developed TB.</sec><sec><title>CONCLUSION</title>Xpert Ultra 'trace' results are common, with wide variation between populations and inconsistencies in interpretation. The implications of a 'trace' result for clinical management and reporting categorisation require greater clarity.</sec>.