Browsing by Subject "Tuberculin skin test"

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    Open Access
    Effectiveness of control measures to prevent occupational tuberculosis infection in health care workers: a systematic review
    (BioMed Central, 2018-05-25) Schmidt, Bey-Marrié; Engel, Mark E; Abdullahi, Leila; Ehrlich, Rodney
    Background A number of guideline documents have been published over the past decades on preventing occupational transmission of tuberculosis (TB) infection in health care workers (HCWs). However, direct evidence for the effectiveness of these controls is limited particularly in low-and middle-income (LMIC) countries. Thus, we sought to evaluate whether recommended administrative, environmental and personal protective measures are effective in preventing tuberculin skin test conversion among HCWs, and whether there has been recent research appropriate to LMIC needs. Methods Using inclusion criteria that included tuberculin skin test (TST) conversion as the outcome and longitudinal study design, we searched a number of electronic databases, complemented by hand-searching of reference lists and contacting experts. Reviewers independently selected studies, extracted data and assessed study quality using recommended criteria and overall evidence quality using GRADE criteria. Results Ten before-after studies were found, including two from upper middle income countries. All reported a decline in TST conversion frequency after the intervention. Among five studies that provided rates, the size of the decline varied, ranging from 35 to 100%. Since all were observational studies assessed as having high or unclear risk of bias on at least some criteria, the overall quality of evidence was rated as low using GRADE criteria. Conclusion We found consistent but low quality of evidence for the effectiveness of combined control measures in reducing TB infection transmission in HCWs in both high-income and upper-middle income country settings. However, research is needed in low-income high TB burden, including non-hospital, settings, and on contextual factors determining implementation of recommended control measures. Explicit attention to the reporting of methodological quality is recommended. Trial registration This systematic review was registered with PROSPERO in 2014 and its registration number is CRD42014009087 .
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    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.