Tracing TB: Are there predictors for active TB disease in patients with Xpert Ultra trace results?

OBJECTIVES The Xpert MTB/Rif Ultra (Xpert Ultra; Cepheid, USA) has an increased sensitivity, compared to its predecessor (Gene Xpert), due to the addition of multicopy amplification targets and a novel trace call. The World Health Organization suggests that in patients with trace results, TB treatment should be initiated in people living with HIV, paediatric, and extra-pulmonary TB patients. However, in high burden TB settings, other factors such as previous TB disease may complicate the interpretation of trace results. This study aims to clarify the positive predictors for active TB disease in patients with trace results and to investigate if previous TB disease influences TB culture positivity. DESIGN We performed a retrospective descriptive study on 290 patients with trace results to determine what the positive predictors for active TB are, by comparing clinical factors to TB culture. RESULTS The key findings of this study are that extra-pulmonary TB samples (odds ratio: 2.7; p=0.012), no previous TB disease (odds ratio: 4.5; p=0.001), and symptoms suggestive of TB (odds ratio: 6.4; p<0.001) are independent predictors for active TB disease. CONCLUSION This study revealed readily available clinical predictors which can aid clinicians with TB management decisions in patients with trace results.