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. 2015 Mar 19;181(8):619–632. doi: 10.1093/aje/kwu320

Table 2.

Summary of Changes Made to Individual Factors When Estimating the Maximum Achievable Impact of Thibela TB (Objective 2) or What Might Control Tuberculosis in the Mines (Objective 3)

Factor Value Based on Empirical Data From the Trial Explored Value
Objective 2 (The Best Achievable Impact in Thibela TB) Objective 3 (What Might Control TB
in Gold Mines)
Initial loss to follow-up sm+: 25%–40%; sm−: 50%–60% 5% As for objective 2
Average treatment delay after detection sm−: 7–9 weeks (45%–60% within 3 months); sm+: 3–4 weeks (55%–75% within 1 month) sm−: 3 weeks (90% within 3 months); Without Xpert MTB/RIF: as for objective 2; with Xpert MTB/RIF: 2 weeks for both sm+ and sm−a,b
sm+: 2 weeks (90% within 1 month)a,b
Sensitivity of case screening on enrollment into Thibela TB 50% on average ∼100% (potentially achievable if culture had been used instead of smear for suspected TB at the initial screen) Not applicable
Preventive treatment 9 months of IPT is provided for all individuals at observed levels of coverage and retention (refer to Web Figure 1 for the proportion on IPT achieved during the trial). 9 months of IPT is provided for all individuals, but 1) uptake and/or 2) retention equals that in the best-performing cluster in Thibela TB. With both optimized, the proportion on IPT equals that for cluster 7 (70%–80% of the cluster on IPT at the peak)c 1) Mass community-wide IPT: 9 months of IPT is provided for all individuals, with coverage and retention equaling those in the best-performing cluster (cluster 7) in Thibela TB. The proportion of infections that are cured and the protection provided against reinfection equal those associated with the greatest impact in objective 1.
2) Continuous IPT for 50% of the population: 9 months of IPT is provided as directly above, with those still taking IPT 9 months after starting it (∼50% of the population) continuing to do so, along with 50% of new mining employeesa
3) 3-month curing regimen: isoniazid and rifapentine, similar to that described in the report by Sterling et al. (47) provided as directly above. Infections are considered to be cured after completing the regimen, and recipients experience 100% protection against reinfection during the regimen.a
ART coverage 0% in 2003, increasing to ∼70% among those with a CD4 count of <200 cells/mL by 2013d,e No change Increased from the levels in 2008 to reach 80% by 2009 among those eligible, defined for 3 criteria: those with a CD4 count of <350 cells/mL, <500 cells/mL, or all HIV-positivesa
TB disease detection and diagnosis All miners at their routine medical examination (approximately every 1.5 years) and new mining employees are screened using radiographs. Those with suspected TB are investigated by using either culture (company A) or with culture for those with previous TB and smear otherwise (companies B/C).Cases presenting passively are investigated with culture (company A) or with smear and/or radiological/clinical signs (companies B/C). No change Sensitivity of Xpert MTB/RIF is assumed to be 55% and 97% for sm− and sm+ TB disease, respectively; refer to the report by Dorman et al. (48). 1) Screen with radiographs and diagnose suspects with Xpert MTB/RIF. Radiographs are used to screen miners presenting at the routine medical examination or when joining the workforce, in the same way that they are used in current practice (and therefore with the same sensitivity), but Xpert MTB/RIF is used to diagnose suspected TB both in the routine medical examination and on passive presentation.a,f 2) Screen and diagnose with Xpert MTB/RIF. Xpert MTB/RIF is used to screen and diagnose cases in the routine medical examination, when joining the workforce, and for miners who self-present.a,f

Abbreviations: ART, antiretroviral therapy; HIV, human immunodeficiency virus; IPT, isoniazid preventive therapy; sm− and sm+, smear-negative and smear-positive, respectively; TB, tuberculosis.