Performance Characteristics of GenXpert MTB/rif in Armenia

Abstract

Global TB control efforts have been severely hampered by the lack of diagnostic tests that are accurate, simple to use and can be applied at the point of clinical care. This has been further compounded by the widespread inability to test for drug resistance. We estimated the performance Characteristics of GenXpert MTB/rif of an active case finding program in Armenia where TB notifications is high. Armenia remains in the top ten out of the 27 high multidrug-resistant (MDR) TB burden countries in the world. According to the latest representative 2007 Drug Resistance Survey (DRS) 9.4% of new cases and 43.2% of previously treated cases were multi-drug resistant. Of these, 4% were extensively-drug-resistant tuberculosis (XDR/TB) cases. Detection of MDR-TB in Armenia remains at 37%. Despite of the fact that in 2013 all detected MDR-TB cases were enrolled in MDR-TB treatment, treatment success rate among 2011 MDR-TB cohort remains 51%, with 26% of patients defaulted therapy mostly due to labour migration, as the main reason of poor outcomes. Moreover, this can be accomplished using unprocessed sputum samples as well as clinical specimens from extrapulmonary sites. We review the development of this assay, its evaluation within the laboratory, its utility among adult and pediatric TB suspects, its use as a screening tool for HIV-associated TB and studies of its implementation at the central level. The Xpert® MTB/RIF assay is a rapid molecular assay that can be used close to the point of care by operators with minimal technical expertise, enabling diagnosis of TB and simultaneous assessment of rifampicin resistance to be completed within 2 h.