Xpert MTB/XDR implementation in South Africa: cost outcomes of centralised vs. decentralised approaches

INTRODUCTIONIn South Africa, Xpert ® MTB/RIF Ultra (Ultra) is the recommended diagnostic assay for TB with line-probe assays for first- (LPAfl) and second-line drugs (LPAsl) providing additional drug susceptibility testing (DST) for samples that were rifampicin-resistant (RR-TB). To guide implementation of the recently launched Xpert ® MTB/XDR (MTB/XDR) assay, a cost-outcomes analysis was conducted comparing total costs for genotypic DST (gDST) for persons diagnosed with RR-TB considering three strategies: replacing LPAfl/LPAsl (centralised level) with MTB/XDR vs. Ultra reflex testing (decentralised level). Further, DST was performed using residual specimen following RR-TB diagnosis. METHODSThe total cost of gDST was determined for three strategies, considering loss to follow-up (LTFU), unsuccessful test rates, and specimen volume. RESULTSFor 2019, 9, 415 persons were diagnosed with RR-TB. A 35% LTFU rate between RR-TB diagnosis and LPAfl/LPAsl-DST was estimated. Unsuccessful test rates of 37% and 23. 3% were reported for LPAfl and LPAsl, respectively. The estimated total costs were 191, 472 for the conventional strategy, 122, 352 for the centralised strategy, and 126, 838 for the decentralised strategy. However, it was found that sufficient residual volume for reflex MTB/XDR testing is a limiting factor at the decentralised level. CONCLUSIONCentralising the implementation of XDR testing, as compared to LPAfl/LPAsl, leads to significant cost savings.