Evaluation of expanded rapid drug susceptibility testing for multidrug resistant tuberculosis in South Africa

Background: New rapid molecular methods for tuberculosis (TB) drug susceptibility testing have shown favorable diagnostic accuracy, but the impact of implementation in routine practice and cost-effectiveness remain unknown.;Methods: Data were collected on all newly registered adult pulmonary TB patients from 25 public health facilities in Kimberley, South Africa, from the periods before and after the introduction of the expanded testing algorithm using MTBDR_plus, a commercially available line probe assay. A hypothetical cohort of 1,000 TB patients was analyzed through a decision model to estimate the incremental cost of each strategy per disability adjusted life year (DALY) averted.;Results: DST increased four-fold between the two study periods. Before introduction of the new testing strategy, multidrug resistant tuberculosis (MDR-TB) prevalence among new TB cases was 0.7% (95% confidence interval (CI):1.4-3.1%), while among previously treated cases it was 6.2% (95% CI:3.5-8.8%). After the introduction, MDR-TB prevalence increased among new cases to 3.7% (95% CI: 2.4-5.0, p 0.003), while among retreatment cases it was 6.6% (95% CI: 3.8-9.4%, p 0.828). The median time from initial sputum collection to MDR treatment in the period before implementation was 78 days (interquartile range (IQR): 52-93), while afterwards it was 62 days (IQR: 32-86, p0.045). MTBDR _plus cost more per sample (;Conclusions: This work illustrates the mixture of successes and challenges that resulted from increasing access to DST and the introduction of a new rapid diagnostic in South Africa. More MDR-TB was found using this new strategy, time to MDR treatment was shorter as a result of the rapid nature of the test, and more MDR-TB patients converted to culture negative by eight months following treatment. However, time to appropriate MDR TB treatment in this setting is still too long. Strategies testing all TB patients using MTBDR_plus are highly cost-effective.