Browsing by Author "Samandari, Taraz"

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    Open Access
    The proportions of people living with HIV in low and middle-income countries who test tuberculin skin test positive using either a 5mm or a 10mm cut-off: a systematic review
    (BioMed Central Ltd, 2013) Kerkhoff, Andrew; Gupta, Ankur; Samandari, Taraz; Lawn, Stephen
    BACKGROUND:A positive tuberculin skin test (TST) is often defined by skin induration of [greater than or equal to]10mm in people who are HIV-seronegative. However, to increase sensitivity for detection of Mycobacterium tuberculosis infection in the context of impaired immune function, a revised cut-off of [greater than or equal to]5mm is used for people living with HIV infection. The incremental proportion of patients who are included by this revised definition and the association between this proportion and CD4+ cell count are unknown. METHODS: The literature was systematically reviewed to determine the proportion of people living with HIV (PLWH) without evidence of active tuberculosis in low and middle-income countries who tested TST-positive using cut-offs of [greater than or equal to]5mm and [greater than or equal to]10mm of induration. The difference in the proportion testing TST-positive using the two cut-off sizes was calculated for all eligible studies and was stratified by geographical region and CD4+ cell count. RESULTS: A total of 32 studies identified meeting criteria were identified, providing data on 10,971 PLWH from sub-Saharan Africa, Asia and the Americas. The median proportion of PLWH testing TST-positive using a cut-off of [greater than or equal to]5mm was 26.8% (IQR, 19.8-46.1%; range, 2.5-81.0%). Using a cut-off of [greater than or equal to]10mm, the median proportion of PLWH testing TST-positive was 19.6% (IQR, 13.7-36.8%; range 0-52.1%). The median difference in the proportion of PLWH testing TST-positive using the two cut-offs was 6.0% (IQR, 3.4-10.1%; range, 0-37.6%). Among those with CD4+ cell counts of <200, 200-499 and [greater than or equal to]500 cells/muL, the proportion of positive tests defined by the [greater than or equal to]5mm cut-off that were between 5.0 and 9.9mm in diameter was similar (12.5%, 12.9% and 10.5%, respectively). CONCLUSIONS: There is a small incremental yield in the proportion of PLWH who test TST-positive when using an induration cut-off size of [greater than or equal to]5mm compared to [greater than or equal to]10mm. This proportion was similar across the range of CD4+ cell strata, supporting the current standardization of this cut-off at all levels of immunodeficiency.
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    Open Access
    Systematic review of TST responses in people living with HIV in under-resourced settings: implications for isoniazid preventive therapy
    (Public Library of Science, 2012) Kerkhoff, Andrew D; Kranzer, Katharina; Samandari, Taraz; Nakiyingi-Miiro, Jessica; Whalen, Christopher C; Harries, Anthony D; Lawn, Stephen D
    BACKGROUND: People living with HIV (PLWH) who have positive tuberculin skin tests (TST) benefit from isoniazid preventive therapy (IPT) whereas those testing TST-negative do not. Revised World Health Organization guidelines explicitly state that assessment of TST is not a requirement for initiation of IPT. However, it is not known what proportions of patients will benefit from IPT if implemented without targeting according to TST status. We therefore determined the proportions of PLWH who test TST-positive. METHODOLOGY/PRINCIPAL FINDINGS: We systematically reviewed the literature published between January 1990 and February 2012 to determine the proportions of patients without active tuberculosis attending HIV care services in low and middle-income countries who tested TST-positive (≥5 mm induration). Proportions were also determined for different CD4 count strata. Data from 19 studies with 9,478 PLWH from sub-Saharan Africa, Asia and Central and South America were summarized. The vast majority were not receiving antiretroviral therapy (ART). A sub-analysis was conducted of 5 studies (5,567 subjects) from high TB prevalence countries of PLWH with negative TB screens attending HIV care and treatment settings for whom CD4 stratified data were available. The median proportion of PLWH testing TST-positive overall was 22.8% (range, 19.5-32.6%). The median (range) proportions with CD4 cell counts of <200, 200-499 or ≥500 cells/µL who tested positive were 12.4% (8.2-15.3%), 28.4% (20.1-36.9%) and 37.4% (31.3-56.3%), respectively. Heterogeneity in the data precluded calculation of pooled summary estimates. Conclusions/Significance In most settings, if IPT is administered to PLWH pre-ART without assessment of TST status, only a minority of those treated are likely to benefit, especially among those with the lowest CD4 cell counts. This may be inefficient use of resources and cost-effectiveness analyses should take this into account. Local knowledge of TST response rates may help inform policies. New simple means of identifying those who will benefit from IPT are needed to permit appropriate targeting of this intervention.