Diagnostic performance and impact of routinely implemented Xpert® MTB/RIF assay in a setting of high incidence of drug-resistant TB in Odessa Oblast, Ukraine

Abstract

Objectives and methods: The Xpert® MTB/RIF assay (Cepheid, Sunnyvale, CA, USA) has been in routine use in Odessa Oblast, a region with the highest tuberculosis (TB) incidence in Ukraine, since 2013. We assessed the performance of the assay in routine settings and evaluated its effect on treatment outcomes.

Results: The sensitivity of Xpert for TB detection was 93.7% (1165/1243) and 69.5% (448/645) for smear-positive and smear-negative sputum specimens, respectively, and its sensitivity for rifampicin resistance was 93.4% (1212/1298). Median time to TB detection using the Xpert assay was 0 days. Treatment initiation within 1 week increased the proportion of successful outcomes (60.1% versus 25.9%, RR = 1.86, 95%CI = 1.46-2.42), but the introduction of Xpert MTB/RIF has not led to a significant improvement in treatment outcomes (57.2% versus 46.2%; RR = 0.93, 95%CI = 0.77-1.12).

Conclusion: Performance characteristics of the Xpert assay demonstrated during its routine implementation in an area of high TB and drug-resistant TB incidence in Ukraine were in line with those demonstrated in similar settings elsewhere. Rollout of rapid molecular testing may lead to better treatment results provided that it is implemented in conjunction with other programmatic improvements.

Keywords: Clinical outcome; Laboratory diagnostics; Molecular assay; Performance; Tuberculosis.