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. 2014 Oct 19;14:532. doi: 10.1186/1471-2334-14-532

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© van’t Hoog et al.; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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Number needed to screen to find one true case of active TB and positive predictive value of each algorithm at different levels of TB prevalence. Panel A: Number needed to screen (NNS) to find one true positive (TP) case; Panel B: Positive predictive value (PPV). CXR = chest X-ray for screening; SSM = sputum smear microscopy; XP = Xpert MTB/RIF; 1 = first screen; 2 = second screen if first is positive.