Implementation and Operational Research: Clinical Impact of the Xpert MTB/RIF Assay in Patients With Multidrug-Resistant Tuberculosis

Abstract

Background: The Xpert MTB/RIF assay has been widely implemented in South Africa for rapid tuberculosis (TB) screening. However, its usefulness in management and improving treatment outcomes in patients with multidrug-resistant TB (MDR-TB) remains undefined. The aim of this study was to evaluate the clinical impact of introduction of the Xpert MTB/RIF assay in patients with MDR-TB.

Methods: We enrolled 921 patients with MDR-TB, who presented to a specialist drug-resistant TB facility in KwaZulu-Natal, South Africa, pre- and post-rollout and implementation of the Xpert MTB/RIF assay. Clinical, laboratory, chest radiograph, and follow-up data from 108 patients with MDR-TB, post-introduction of the Xpert MTB/RIF assay (Xpert group) in November 2010, were analyzed and compared with data from 813 MDR-TB patients from the pre-MTB/RIF assay period (Conventional group), July 2008-2010. Primary impact measure was "treatment success" (World Health Organization definition) at 24 months. Secondary outcomes were time to treatment initiation and disease morbidity.

Results: There were no significant differences in treatment success rates between the pre-Xpert MTB/RIF and post-Xpert MTB/RIF groups (54% versus 56.5%, P = 0.681). Median time to treatment initiation was 20 days (interquartile range, 13-31) in the Xpert group versus 92 days (interquartile range, 69-120) in the Conventional group (P < 0.001).

Conclusions: Although use of Xpert MTB/RIF assay significantly reduces the time to initiation of MDR-TB treatment, it had no significant impact on treatment outcomes of patients with MDR-TB. Studies on the impact of the Xpert MTB/RIF assay usage on transmission of MDR-TB are required.