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. 2014 Nov 1;67(3):e88-93.
doi: 10.1097/QAI.0000000000000309.

Diagnostic delays and clinical decision making with centralized Xpert MTB/RIF testing in Durban, South Africa

Gabriel M Cohen  1 , Paul K Drain, Farzad Noubary, Christie Cloete, Ingrid V Bassett
Affiliations

Diagnostic delays and clinical decision making with centralized Xpert MTB/RIF testing in Durban, South Africa

Gabriel M Cohen et al. J Acquir Immune Defic Syndr. .

Abstract

Setting: We conducted a retrospective study among HIV-infected adult suspects (≥18 years) with pulmonary tuberculosis (TB), who underwent Xpert MTB/RIF (Xpert) testing at McCord Hospital and its adjoining HIV clinic in Durban, South Africa.

Objective: To determine if Xpert testing performed at a centralized laboratory accelerated time to TB diagnosis.

Design: We obtained data on sputum smear microscopy [acid-fast bacilli (AFB)], Xpert, and the rationale for treatment initiation from medical records. The primary outcome was "total diagnostic time," defined as time from sputum collection to clinicians' receipt of results. A linear mixed-effect model compared the duration of steps in the diagnostic pathway across testing modalities.

Results: Among 403 participants, the median "total diagnostic time" for AFB and Xpert was 3.3 and 6.4 days, respectively (P < 0.001). When compared with AFB, the median delay for Xpert "laboratory processing" was 1.4 days (P < 0.001) and "result transfer to clinic" was 1.7 days (P < 0.001). Among 86 Xpert-positive participants who initiated treatment, 49 (57%) started treatment based on clinical suspicion or AFB-positive results, whereas only 32 (37%) started treatment based on Xpert-positive results.

Conclusions: In our setting, Xpert results took twice as long as AFB results to reach clinicians. Replacing AFB with centralized Xpert may delay TB diagnoses in some settings.

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Figures

Figure 1
Figure 1
Median time between consecutive events from sputum specimen collection to a clinician's receipt of test results, for AFB and Xpert tests.
Figure 2
Figure 2
The rationale for TB treatment initiation among participants with both AFB and Xpert results (A, N=124), AFB-positive results (B, N=56) AFB-negative results (C, N=68), Xpert-positive results (D, N=86), or Xpert-negative results (E, N=38).
See this image and copyright information in PMC

References

    1. World Health Organization (WHO) Global Tuberculosis Control 2011. WHO; Geneva, Switzerland: 2011.
    1. Bassett IV, Wang B, Chetty S, et al. Intensive tuberculosis screening for HIV-infected patients starting antiretroviral therapy in Durban, South Africa. Clin. Infect. Dis. 2010 Oct 1;51(7):823–9. - PMC - PubMed
    1. Lawn SD, Brooks SV, Kranzer K, et al. Screening for HIV-associated tuberculosis and rifampicin resistance before antiretroviral therapy using the Xpert MTB/RIF assay: a prospective study. PLoS Med. 2011 Jul;8(7):e1001067. - PMC - PubMed
    1. Lawn SD, Kerkhoff AD, Vogt M, Wood R. Diagnostic accuracy of a low-cost, urine antigen, point-of-care screening assay for HIV-associated pulmonary tuberculosis before antiretroviral therapy: a descriptive study. Lancet Infect. Dis. 2012 Mar 17;12(3):201–9. - PMC - PubMed
    1. Lawn SD, Wood R. Tuberculosis in antiretroviral treatment services in resource-limited settings: addressing the challenges of screening and diagnosis. J. Infect. Dis. 2011 Nov;204(Suppl):S1159–67. - PMC - PubMed

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