title: Cost-effectiveness of rapid susceptibility testing against second-line drugs for tuberculosis.
abstract: BACKGROUND
  Drug susceptibility testing (DST) against second-line tuberculosis drugs (SLDs) is essential for improving outcomes among multidrug-resistant (MDR-) and extensively drug-resistant tuberculosis (XDR-TB) cases.
  
  
  OBJECTIVE
  To evaluate the potential cost-effectiveness of rapid DST for SLDs.
  
  
  METHODS
  We constructed a decision analysis model of Xpert MTB/RIF-based TB diagnosis in East and South-East Asia to compare culture-based DST vs. a hypothetical rapid SLD DST system for specimens resistant to rifampin. Our primary outcomes were the effectiveness and incremental cost-effectiveness of a rapid SLD DST assay relative to culture-based DST.
  
  
  RESULTS
  For rapid SLD DST to be more effective than culture-based DST, treating individuals with pre-XDR/XDR-TB with a standardized MDR-TB regimen while awaiting culture-based DST must incur at least 30% excess XDR-TB mortality (100% = treatment with first-line drugs); rapid SLD DST should attain an aggregate sensitivity and specificity for all pre-XDR/XDR mutations of 88% and 96%, respectively. The unit cost of the rapid SLD DST assay must approach that of culture to achieve common thresholds for cost-effectiveness in low-income countries.
  
  
  CONCLUSIONS
  Rapid SLD DST has the potential to be cost-effective, but must meet stringent criteria for accuracy and costs, and requires that standardized second-line treatment for pre-XDR/XDR-TB incur substantial excess mortality before the return of culture results.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Dowdy
authors.affiliation: Department of Global Health and Amsterdam Institute for Global Health and Development, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: van't Hoog
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: M
authors.initials: M
authors.lastname: Shah
authors.affiliation: Department of Global Health and Amsterdam Institute for Global Health and Development, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: F
authors.initials: F
authors.lastname: Cobelens
mesh_terms: D000465:Algorithms; D000995:Antitubercular Agents / Q000627:therapeutic use*; D001208:Asia; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D003663:Decision Trees; D016527:Drug Costs; D024901:Drug Resistance, Multiple, Bacterial; D054908:Extensively Drug-Resistant Tuberculosis / Q000175:diagnosis / Q000188:drug therapy* / Q000191:economics / Q000382:microbiology / Q000401:mortality; D017048:Health Care Costs; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000191:economics*; D018803:Models, Economic; D011237:Predictive Value of Tests; D016896:Treatment Outcome; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis / Q000188:drug therapy* / Q000191:economics / Q000382:microbiology / Q000401:mortality
chemical_list: D000995:Antitubercular Agents