S120 Diagnostic accuracy of TB PCR in EBUS-TBNA samples, TRIBE a multicentre prospective UK study

<h3>Introduction</h3> The utility of TB PCR (Xpert Ultra®) in endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) samples remains unclear in a low incidence high resource setting. <h3>Aims</h3> To analyse the diagnostic accuracy of Xpert Ultra for the detection of MTB in EBUS-TBNA samples in culture positive lymph node TB cases. <h3>Methods</h3> This multicentre prospective study across 10 units analysed EBUS-TBNA samples from January 2021 to December 2022. Routine EBUS-TBNA results for TB PCR, microscopy, culture, cytology and rapid onsite evaluation of cytology (ROSE) where available were reviewed alongside their clinical data. Turnaround times (TAT) from sample collection were measured for each test. Trace readings for Xpert Ultra were analysed both as a positive and negative result. <h3>Results</h3> A total of 293 EBUS-TBNA samples were analysed from participants with a median age of 51.8 (IQR 37.4–67.5), M:F ratio of 172:121, 4 cases were co-infected with HIV, 67 with diabetes and 27 cases with previous TB. 34/293 (11.6%) were culture positive from the mediastinal lymph nodes. The diagnostic accuracies of routine TB tests are shown in table 1. There were 2 Xpert Ultra trace readings but both in TB naïve cases with one being culture positive and one culture negative but clinically being treated for TB. The median TAT for culture positivity was 21.5 days (IQR 15.25–39.75) but ROSE, Xpert Ultra and smear had the same day TAT. TAT for cytology was 4 days (IQR 2–6). <h3>Conclusion</h3> Xpert Ultra has a considerably higher diagnostic yield compared to smear microscopy in EBUS-TBNA samples and is associated with a high sensitivity. It has a rapid TAT with the ability to identify rifampicin resistance and with a significant lead time advantage to culture. The data argue for a health-economic analysis to determine its value as a first-line test that replaces smear in people with possible mediastinal nodal TB.