Introducing new tuberculosis diagnostics: the impact of Xpert(®) MTB/RIF testing on case notifications in Nepal

Abstract

Setting: The Xpert(®) MTB/RIF assay is a highly sensitive molecular test with the potential to improve tuberculosis (TB) case detection. However, evidence supporting this potential at a programme level is minimal.

Methods: Xpert testing following smear microscopy and chest X-ray was implemented as part of routine case finding in 16 districts of Eastern Nepal. Changes in TB case notification were evaluated based on a pre/post analysis, as were expected notifications based on linear trend.

Results: A total of 9723 Xpert tests were performed, resulting in the identification of 1662 Mycobacterium tuberculosis-positive patients. Despite a previous declining trend in notifications, annual bacteriologically positive TB notifications increased by 15.2% during the intervention, from 3390 to 3906. However, annual notifications of pulmonary TB dropped by 8.5% overall, from 5123 to 4688. Both observations were significantly different from expected notifications based on historical trends. Treatment initiation for drug-resistant TB almost doubled.

Discussion: Xpert testing significantly increased bacteriologically positive TB notifications, but large reductions in empiric treatment of smear-negative disease reduced the number of pulmonary TB notifications overall. While better diagnostics remain critical, focusing solely on superior test sensitivity may not increase TB case notifications. Additional interventions are required to reach the millions of people with TB who are missed by routine services.