LAUSR

Background: Uganda introduced Xpert MTB/RIF assay into its TB diagnostic algorithm in January 2012. In July 2018, this assay was replaced with Xpert MTB/RIF Ultra assay. We set out to compare the tests done and tuberculosis cases detected by Xpert MTB/RIF and Xpert MTB/RIF Ultra assay in Uganda. Methods: This was a before and after study, with the tests done and TB cases detected between Jan-June 2019 when using Xpert MTB/RIF Ultra assay compared to those done between Jan-June 2018 while using Xpert MTB/RIF assay. This data was analyzed using Stata version 13, it was summarized into measures of central tendency and the comparison between Xpert MTB/RIF Ultra and Xpert MTB/RIF was explored using a two-sided T-test which was considered significant if p <0.05. Results: One hundred and twelve (112) GeneXpert sites out of a possible 239 were included in the study. 128,476 (M: 1147.11, SD: 842.88) tests were performed with Xpert MTB/RIF Ultra assay, with 9693 drug-susceptible TB (DS-TB) cases detected (M: 86.54, SD: 62.12) and 144 (M: 1.28, SD: 3.42) Rifampicin Resistant TB cases (RR-TB). Whilst 107, 890 (M: 963.30, SD: 842.88) tests were performed with Xpert MTB/RIF assay between, 8807 (M: 78.63, SD: 53.29) DS-TB cases were detected, and 147 (M: 1.31, SD: 2.39) RR-TB cases. The Number Need to Test (NNT) to get one TB case was 12 for Xpert MTB/RIF and 13 for Xpert MTB/RIF Ultra. On comparing the two assays in terms of test performance (p=0.75) and case detection both susceptible TB (p=0.31) and RR-TB (p=0.95) were not found statistically significant. Conclusions: This study found no significant difference in test performance and overall detection of DS-TB and RR-TB when using Xpert MTB/RIF Ultra and Xpert MTB/RIF assays. The health systems approach should be used to elucidate all the probable potential of Xpert MTB/RIF Ultra.