Tuberculosis control in South African gold mines: mathematical modeling of a trial of community-wide isoniazid preventive therapy.
Bottom Line: A recent major cluster randomized trial of screening, active disease treatment, and mass isoniazid preventive therapy for 9 months during 2006-2011 among South African gold miners showed reduced individual-level tuberculosis incidence but no detectable population-level impact.We found the following: 1) The model suggests that a small proportion of latent infections among human immunodeficiency virus-positive people were cured, which could have been a key factor explaining the lack of detectable population-level impact. 2) The optimized implementation increased impact by only 10%. 3) Implementing additional interventions individually and in combination led to up to 30% and 75% reductions, respectively, in tuberculosis incidence after 10 years.Tuberculosis control requires a combination prevention approach, including health systems strengthening to minimize treatment delay, improving diagnostics, increased antiretroviral treatment coverage, and effective preventive treatment regimens.
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Mentions: After incorporating all known data and factors (migration, ART uptake, silicosis, IPT uptake and retention, treatment delay, and initial loss to follow-up) and fitting to the observed outcomes, we found that the model based on IPT assumptions 1 (100% cure, 100% protection) fitted the data poorly. The best-fitting impact of 24.5% (95% CI: 24.2, 25.0) and 17.8% (95% CI: 15.0, 21.0) on the measured incidence for IPT assumptions 1 and 2, respectively, exceeded that observed but was inside the latter's 95% confidence interval (−48, 27) (Figure 4A). Findings for the best-fitting impact on prevalence were similar. Web Appendix 5, Web Table 12, and Web Figures 10–14 include further details.Figure 4.