Table 2.
Parameters.
| TB parametersa | |||
| Parameter | Description | Calibrated value | Source |
| Transmission rate | Rate of TB transmission | 0.0000004 | Sensitivity analysis |
| Latency rate upon infection in HIV− | Rate at which HIV− individuals infected with TB remain latently, rather than actively, infected | 0.9 | Abu-Raddad et al. [22]b |
| Latency rate upon infection in HIV+ | Rate at which HIV+ individuals infected with TB remain latently, rather than actively, infected | 0.5 | Lawn et al. [7] |
| Latency rate upon infection in HIV+ on ART | Rate at which HIV+ individuals on ART infected with TB remain latently, rather than actively, infected | 0.9 | Abu-Raddad et al. [22]b |
| TB activation rate in HIV− | Rate at which HIV− individuals experience latent TB activation | 0.005 | Horsburgh [23] |
| TB activation rate in HIV+ | Rate at which HIV+ individuals experience latent TB activation | 0.09 | Sensitivity analysis |
| TB activation rate in ART | Rate at which HIV+ individuals on ART experience latent TB activation | 0.005 | Horsburgh [23] |
| TB treatment rate | Rate at which TB is treated with combination therapy | 0.9 | WHO [1] |
| Recovery rate for combination therapy | Rate at which individuals with TB recover when treated with combination therapy | 0.9 | WHO [1], Bacaër et al. [24]b |
| Return to latency after combination therapy | Rate at which individuals receiving combination therapy for active TB return to latent TB | 0.08 | Suen et al. [25]b |
| Recovery rate for IPT | Rate at which individuals recover on IPT | 0.47 | Zelner et al. [26] |
| TB activation rate on IPT for HIV− | Rate at which HIV− individuals latently infected with TB experience TB activation | 0.0001 | Houben et al. [27]b |
| TB activation rate on IPT for HIV+ | Rate at which HIV+ individuals latently infected with TB experience TB activation | 0.0001 | Houben et al. [27]b, Selwyn et al. [28], Lin and Flynn [29] |
| Non-cure on combination therapy | Rate at which individuals who have received combination therapy are not cured | 0.02 | Suen et al. [25]b |
| Natural cure rate | Rate at which individuals with active TB experience spontaneous resolution to latent TB | 0.1 | Tiemersma et al. [30] |
| Incorrect diagnosis rate in HIV− | Rate at which HIV− individuals who are actively infected with TB are incorrectly diagnosed as latently infected | 0.00001 | Boehme et al. [31] |
| Incorrect diagnosis rate in HIV+ | Rate at which HIV+ individuals not on ART who are actively infected with TB are incorrectly diagnosed as latently infected | 0.0001 | Boehme et al. [31] |
| Incorrect diagnosis rate in HIV+ on ART | Rate at which HIV+ individuals on ART who are actively infected with TB are incorrectly diagnosed as latently infected | 0.00001 | Boehme et al. [31] |
| Correct move from IPT to combination therapy | Rate at which individuals who had incorrectly been placed on combination therapy are redirected to IPT | 0.9 | Boehme et al. [31] |
| Reinfection adjustment | Factor to adjust for the possibility of reinfection with TB following treatment and cure | 0.21 | Andrews et al. [21]b |
| IPT access rate | Rate at which individuals latently infected with TB are placed on IPT | 0.05/0.5/0.9 | Sensitivity analysis |
| Default rate on IPT | Rate at which individuals on IPT default | 0 | Sensitivity analysis |
| Rate of ceasing IPT | Rate at which individuals on IPT stop treatment | 0 | Sensitivity analysis |
| HIV parametersc | |||
| Parameter | Description | Value | Source |
| HIV infection in adolescents | Rate at which adolescents are infected with HIV | 0.0000000039 | Auvert et al. [32] |
| HIV infection in adults | Rate at which adults are infected with HIV | 0.0000000039 | Calibration |
| Progression of CD4+ cell count | Rate at which individuals infected with HIV progress to ART eligibility (experience CD4+ cell count decline) | 0.13 | Mellors et al. [33] |
| Access to ART | Rate at which eligible HIV+ individuals are placed on ART | 0.02/ 0.1 | Calibration |
| Recovery of CD4+ cell count on ART | Rate at which HIV+ individuals on ART experience CD4+ cell count recovery | 0.01 | Calibration |
| Demographic parametersd | ||
| Parameter | Description | Value |
| Child natural mortality | Mortality rate among children not infected with TB or HIV | 0.001 |
| Adolescent natural mortality | Mortality rate among adolescents not infected with TB or HIV | 0.009 |
| Adult natural mortality | Mortality rate among adults not infected with TB or HIV | 0.02 |
| HIV+ pre-ART adolescent mortality | Mortality rate among adolescents who are HIV+ and not yet eligible for ART | 0.02 |
| HIV+ pre-ART adult mortality | Mortality rate among adults who are HIV+ and not yet eligible for ART | 0.03 |
| HIV+ ART-eligible adolescent mortality | Mortality rate among adolescents who are HIV+ and eligible for ART | 0.05 |
| HIV+ ART-eligible adult mortality | Mortality rate among adults who are HIV+ and eligible for ART | 0.05 |
| HIV+ on ART low CD4+ cell count adolescent mortality | Mortality rate among adolescents who are HIV+ and on ART with low CD4+ cell count | 0.09 |
| HIV+ on ART low CD4+ cell count Adult Mortality | Mortality rate among adults who are HIV+ and on ART with low CD4+ cell count | 0.02 |
| HIV+ on ART High CD4+ cell count adolescent mortality | Mortality rate among adolescents who are HIV+ and on ART with high CD4+ cell count | 0.09 |
| HIV+ on ART high CD4+ cell count adult mortality | Mortality rate among adults who are HIV+ and on ART with high CD4+ cell count | 0.02 |
| TB adolescent mortality | Mortality rate among adolescents who are infected with TB, and are HIV− | 0.058 |
| TB adult mortality | Mortality rate among adults who are infected with TB, and are HIV− | 0.068 |
| TB & HIV+ pre-ART adolescent mortality | Mortality rate among adolescents who are infected with TB, and are HIV+, not yet eligible for ART | 0.12 |
| TB & HIV+ pre-ART adult mortality | Mortality rate among adults who are infected with TB, and are HIV+, not yet eligible for ART | 0.23 |
| TB & HIV+ ART-eligible adolescent mortality | Mortality rate among adolescents who are infected with TB, and are HIV+, and eligible for ART | 0.17 |
| TB & HIV+ ART-eligible adult mortality | Mortality rate among adults who are infected with TB, and are HIV+, and eligible for ART | 0.3 |
| TB & HIV+ low CD4+ cell count adolescent mortality | Mortality rate among adolescents who are infected with TB, and are HIV+, on ART with low CD4+ cell count | 0.07 |
| TB & HIV+ low CD4+ cell count adult mortality | Mortality rate among adults who are infected with TB, and are HIV+, on ART with low CD4+ cell count | 0.1 |
| TB & HIV+ high CD4+ cell count adolescent mortality | Mortality rate among adolescents who are infected with TB, and are HIV+, on ART with high CD4+ cell count | 0.062 |
| TB & HIV+ high CD4+ cell count adult mortality | Mortality rate among adults who are infected with TB, and are HIV+, on ART with high CD4+ cell count | 0.072 |
| Births | Birth rate | 0.03 |
| Aging rate from children to adolescents | Rate at which children age into the adolescent group | 0.0769 |
| Aging rate from adolescents to adults | Rate at which adolescents age into the adult group | 0.2 |
Parameters used in the model. All parameters subject to adjustment for calibration. ART, antiretroviral therapy; IPT, isoniazid preventive therapy; TB, tuberculosis.
aWith regard to the units of the TB and HIV parameters, each of these parameters is reported as the fraction of the population within a given compartment flowing out of that compartment into another specified by the model diagram per unit time.
bParameter taken as either an input or an output from a modeling publication.
cWith regard to the units of the TB and HIV parameters, each parameter is reported as the fraction of the population within a given compartment flowing out of that compartment into another specified by the model diagram per unit time.
dAll demographic parameters were generated via calibration to the population structure.