The impact of new tuberculosis diagnostics on transmission: why context matters
Hsien-Ho Lin, David Dowdy, Christopher Dye, Megan Murray & Ted Cohen
Volume 90, Number 10, October 2012, 739-747A
Table 1. Selected model parameters and their values in the epidemic tuberculosis model used to study the impact of new tuberculosis diagnostics on transmission
| Parameter description | Prior valuea | Posterior valueb | Temporal unit | Source for prior values |
|---|---|---|---|---|
| Transmission parameter, smear-positive (i.e. no. of people that one smear-positive tuberculosis case can infect in 1 year in a completely susceptible population) | 5.90 (3.63–9.60) | 8.48 (3.24–8.78) | Year | Fitted to the observed tuberculosis epidemic before DOTS implementation |
| Relative magnitude of transmission parameter, smear-negative (relative to smear-positive tuberculosis) | 0.22 (0.15–0.33) | 0.17 (0.14–0.29) | Year | Behr et al. 1999 |
| Incidence of HIV infection | Time-varying | Same as prior values | Year | UNAIDS report |
| Duration of fast latent period | 5 | Same as prior values | Year | Vynnycky & Fine, 1997 |
| Primary progression rate, HIV-negative patient | 0.03 (0.0095–0.094) | 0.029 (0.014–0.056) | Year | Vynnycky & Fine, 1997 |
| Primary progression rate, HIV-positive patient | 0.41 (0.32–0.52) | 0.36 (0.32–0.52) | Year | Antonucci et al. 1995. |
| Slow reactivation rate, HIV-negative patient | 0.0003 (0.000033–0.0028) | 0.00013 (0.000025–0.0016) | Year | Vynnycky & Fine 1997 |
| Slow reactivation rate, HIV-positive patient | 0.10 (0.05–0.19) | 0.08 (0.05–0.19) | Year | Rieder 1999 |
| Reduction of probability of fast progression after reinfection, HIV-negative patient | 0.65 (0.58–0.73) | 0.64 (0.56–0.72) | None | Cohen et al. 2006; |
| Reduction of probability of fast progression after re-infection, HIV-positive patient | 0.25 (0.17–0.37) | 0.18 (0.17– 0.36) | None | Cohen et al. 2006 |
| Percent smear-positive among incident cases of pulmonary tuberculosis, HIV-negative adult | 0.70 (0.63–0.77) | 0.71 (0.64–0.79) | None | Vynnycky & Fine, 1997 |
| Percent smear-positive among incident cases of pulmonary tuberculosis, HIV-positive adult | 0.48 (0.39–0.59) | 0.41 (0.40–0.54) | None | FitzGerald et al. 1991 |
| Percent smear-positive among incident cases of pulmonary tuberculosis, HIV-negative children | 0.17 (0.10–0.28) | 0.21 (0.10–0.25) | None | Vynnycky & Fine, 1997 |
| Percent smear-positive among incident cases of pulmonary tuberculosis, HIV-positive children | 0.10 (0.05–0.19) | 0.04 (0.05–0.18) | None | Assumption |
| Natural cure rate, HIV-negative patient | 0.20 (0.13–0.31) | 0.33 (0.12–0.33) | Year | Dye et al. 1998 |
| Natural cure rate, HIV-positive patient | 0.10 (0.05–0.19) | 0.14 (0.06–0.22) | Year | Assumption |
| Death rate of those with active tuberculosis, smear-positive and untreated, HIV-negative patient | 0.22 (0.15–0.33) | 0.16 (0.14–0.29) | Year | Adapted from Hughes et al. |
| Death rate of those with active tuberculosis, smear-positive and untreated, HIV-positive patient | 1.50 (1.34–1.68) | 1.55 (1.36–1.67) | Year | Adapted from Hughes et al. |
| Death rate of those with active tuberculosis, smear-negative and untreated, HIV-negative patient | 0.19 (0.12–0.30) | 0.18 (0.11–0.28) | Year | Adapted from Hughes et al. |
| Death rate of those with active tuberculosis, smear-negative and untreated, HIV-positive patient | 1.50 (1.34–1.68) | 1.47 (1.37–1.70) | Year | Adapted from Hughes et al. |
| Relapse rate after cure, HIV-negative patient | 0.001 (0.00015–0.0067) | 0.00073 (0.00015–0.0044) | Year | Cohen et al. 2006 |
| Relapse rate after cure, HIV-positive patient | 0.01 (0.0028–0.035) | 0.0058 (0.0026–0.037) | Year | Cohen et al. 2006 |
HIV, human immunodeficiency virus.
a For prior values, either a log-normal distribution or a uniform distribution was assumed; values presented are means and 90% ranges for a log-normal distribution and lower and upper bounds for a uniform distribution
b For posterior values, the modes and 90% ranges are presented. See also Table 2 for several key operational factors and their posterior values. For a comprehensive list of model parameters, see Appendix A