Change in TB diagnostic profile after introduction of GeneXpert MTB/RIF assay in National TB Program of Armenia, 2013-2017

Abstract

Introduction: In 2013, the National Tuberculosis (TB) Program of Armenia introduced GeneXpert MTB/RIF (Xpert) assay to address World Health Organization (WHO) target of 80% (2020) of notified new and relapse TB cases to be tested with WHO recommended rapid diagnostic methods. This study aimed to assess the change in laboratory diagnostic profile of Mycobacterium tuberculosis after introduction of the Xpert assay from 2013 to 2017.

Methodology: Retrospective cohort analysis of all presumptive TB patients' records retrieved from the National Reference Laboratory database was performed.

Results: This study showed increased trend of Xpert coverage for suspected TB cases from 25% in 2013 to 86% in 2017 which is in line with WHO TB global strategy's target of 80% in 2020. In 4.7% cases, Xpert tested positive while microscopy showed negative results. There was also an improved detection of Rifampicin resistance with increased concordance from 99.1% to 99.4% and decreased discordance from 6.7% to 1.4% between culture and Xpert results.

Conclusion: Armenia has achieved the 2020 target; in terms of utilizing the GeneXpert it is on track to achieve the End TB strategy target of 100% by 2025. The next step of this research will be assessment of the impact of GeneXpert and other TB tests utilization on the treatment outcomes in Armenia.

Keywords: Diagnosis; GeneXpert MTB/RIF; Laboratory; NRL; Tuberculosis.