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BackgroundInterferon gamma release assays (IGRA) are replacing the tuberculin skin test (TST) as a diagnostic tool for Mycobacterium tuberculosis infection. However research into the test's performance in the high HIV-TB burden setting is scarce. This study aimed to define the sensitivity of an IGRA, QuantiFERON-TB® Gold In-Tube (QGIT), in adult Zambian patients with active smear-positive tuberculosis. Secondary outcomes focussed on the effect of HIV on the test's performance.Principal FindingsPatients attending government health clinics were recruited within 1 month of starting treatment for TB. Subjects were tested with QGIT and TST. T lymphocyte counts were estimated (CD3+, CD4+, CD8+). QGIT was performed for 112 subjects. 83/112 were QGIT positive giving an overall sensitivity of 74% [95%CI: 66,82]. A marked decrease in sensitivity was observed in HIV positive patients with 37/59 (63%) being QGIT positive compared to 31/37 (84%) HIV negative patients [chi2 p = 0.033]. Low CD4+ count was associated with increases in both indeterminate and false-negative results. Low CD4+ count in combination with high/normal CD8+ count was associated with false-negative results. TST was recorded for 92 patients, 62/92 were positive, giving a sensitivity of 67% [95%CI: 58,77]. Although there was little difference in the overall sensitivities, agreement between TST and QGIT was poor.ConclusionsQGIT was technically feasible with results in HIV negative subjects comparable to those achieved elsewhere. However, where under-treated HIV is prevalent, an increased proportion of both indeterminate and false-negative QGIT results can be expected in patients with active TB. The implications of this for the diagnosis of LTBI by QGIT is unclear. The diagnostic and prognostic relevance of IGRAs in high burden settings needs to be better characterised.

BackgroundThe Zambian Defence Force (ZDF) is working to improve the quality of services to prevent mother-to-child transmission of HIV (PMTCT) at its health facilities. This study evaluates the impact of an intervention that included provider training, supportive supervision, detailed performance standards, repeated assessments of service quality, and task shifting of group education to lay workers.MethodsFour ZDF facilities implementing the intervention were matched with four comparison sites. Assessors visited the sites before and after the intervention and completed checklists while observing 387 antenatal care (ANC) consultations and 41 group education sessions. A checklist was used to observe facilities’ infrastructure and support systems. Bivariate and multivariate analyses were conducted of findings on provider performance during consultations.ResultsAmong 137 women observed during their initial ANC visit, 52% came during the first 20 weeks of pregnancy, but 19% waited until the 28th week or later. Overall scores for providers’ PMTCT skills rose from 58% at baseline to 73% at endline (p=0.003) at intervention sites, but remained stable at 52% at comparison sites. Especially large gains were seen at intervention sites in family planning counseling (34% to 75%, p=0.026), HIV testing during return visits (13% to 48%, p=0.034), and HIV/AIDS management during visits that did not include an HIV test (1% to 34%, p=0.004). Overall scores for providers’ ANC skills rose from 67% to 74% at intervention sites, but declined from 65% to 59% at comparison sites; neither change was significant in the multivariate analysis. Overall scores for group education rose from 87% to 91% at intervention sites and declined from 78% to 57% at comparison sites. The overall facility readiness score rose from 73% to 88% at intervention sites and from 75% to 82% at comparison sites.ConclusionsThese findings are relevant to civilian as well as military health systems in Zambia because the two are closely coordinated. Lessons learned include: the ability of detailed performance standards to draw attention to and strengthen areas of weakness; the benefits of training lay workers to take over non-clinical PMTCT tasks; and the need to encourage pregnant women to seek ANC early.