Calculation Logic for Baseline Model

Value to calculateComponents used in calculationFormulae used
Total annual number of Xpert MTB/RIF tests = Number of tests for HIV+ adults, children, and HIV− adultsNumber of tests for HIV+ adultsEstimated number of PLHIVa · 81%b · 2c · 20%d
Number of tests for childrenEstimated number of children with TBe · 90%f · 4g
Number of tests for HIV− adultsNumber of TB patientse,h · 90%f · Percentage of TB patients who are adultse · Percentage of adults who are HIV−a · 10i
Target number of Xpert modules neededTotal annual number of Xpert MTB/RIF tests/68j · 3k
  • Abbreviations: HIV+, HIV positive; HIV−, HIV negative; MTB, Mycobacterium tuberculosis; TB, tuberculosis; WRD, World Health Organization-recommended rapid diagnostic.

  • a Source: Joint United Nations Programme on HIV/AIDS.

  • b Target percentage of persons living with HIV who are enrolled on ART (90%· 90%).

  • c Number of TB screening visits per year for clients on ART.

  • d Percentage of clients on ART with symptoms that require testing with a WRD.

  • e Source: World Health Organization.

  • f Target for TB-burden coverage.

  • g Number of symptomatic children needed to test with WRD to diagnose 1 child with TB.

  • h All forms, including all incident, relapse, and previously treated.

  • i Number of symptomatic adults needed to test with WRD to diagnose 1 adult with TB.

  • j Number of days per year that WRD module is operational.

  • k Number of test cycles per day per module.