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      Sensitivity of diagnostic tests for human soil-transmitted helminth infections: a meta-analysis in the absence of a true gold standard

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          Abstract

          Highlights

          • A Bayesian latent class meta-analysis of diagnostic tests for soil-transmitted helminths was performed.

          • Overall sensitivity of evaluated diagnostic tests was low.

          • Test performance was strongly influenced by intensity of infection.

          • FLOTAC method sensitivity was highest overall and in both intensity groups.

          • The performance of the Kato-Katz method in high intensity settings was acceptable.

          Abstract

          Reliable, sensitive and practical diagnostic tests are an essential tool in disease control programmes for mapping, impact evaluation and surveillance. To provide a robust global assessment of the relative performance of available diagnostic tools for the detection of soil-transmitted helminths, we conducted a meta-analysis comparing the sensitivities and the quantitative performance of the most commonly used copro-microscopic diagnostic methods for soil-transmitted helminths, namely Kato-Katz, direct microscopy, formol-ether concentration, McMaster, FLOTAC and Mini-FLOTAC. In the absence of a perfect reference standard, we employed a Bayesian latent class analysis to estimate the true, unobserved sensitivity of compared diagnostic tests for each of the soil-transmitted helminth species Ascaris lumbricoides, Trichuris trichiura and the hookworms. To investigate the influence of varying transmission settings we subsequently stratified the analysis by intensity of infection. Overall, sensitivity estimates varied between the different methods, ranging from 42.8% for direct microscopy to 92.7% for FLOTAC. The widely used double slide Kato-Katz method had a sensitivity of 74–95% for the three soil-transmitted helminth species at high infection intensity, however sensitivity dropped to 53–80% in low intensity settings, being lowest for hookworm and A. lumbricoides. The highest sensitivity, overall and in both intensity groups, was observed for the FLOTAC method, whereas the sensitivity of the Mini-FLOTAC method was comparable with the Kato-Katz method. FLOTAC average egg count estimates were significantly lower compared with Kato-Katz, while the compared McMaster counts varied. In conclusion, we demonstrate that the Kato-Katz and Mini-FLOTAC methods had comparable sensitivities. We further show that test sensitivity of the Kato-Katz method is reduced in low transmission settings.

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          Most cited references42

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          FLOTAC: new multivalent techniques for qualitative and quantitative copromicroscopic diagnosis of parasites in animals and humans.

          Accurate diagnosis of parasitic infections is of pivotal importance for both individual patient management and population-based studies, such as drug efficacy trials and surveillance of parasitic disease control and elimination programs, in both human and veterinary public health. In this study, we present protocols for the FLOTAC basic, dual and double techniques, which are promising new multivalent, sensitive, accurate and precise methods for qualitative and quantitative copromicroscopic analysis. These various methods make use of the FLOTAC apparatus, a cylindrical device with two 5-ml flotation chambers, which allows up to 1 g of stool to be prepared for microscopic analysis. Compared with currently more widely used diagnostic methods for parasite detection in animals (e.g., McMaster and Wisconsin techniques) and humans (e.g., Kato-Katz and ether-based concentration techniques), the FLOTAC techniques show higher sensitivity and accuracy. All FLOTAC techniques can be performed on fresh fecal material as well as preserved stool samples, and require approximately 12-15 min of preparation time before microscopic analysis.
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            An ether sedimentation technique for routine stool examinations.

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              Estimation of diagnostic-test sensitivity and specificity through Bayesian modeling.

              We review recent Bayesian approaches to estimation (based on cross-sectional sampling designs) of the sensitivity and specificity of one or more diagnostic tests. Our primary goal is to provide veterinary researchers with a concise presentation of the computational aspects involved in using the Bayesian framework for test evaluation. We consider estimation of diagnostic-test sensitivity and specificity in the following settings: (i) one test in one population, (ii) two conditionally independent tests in two or more populations, (iii) two correlated tests in two or more populations, and (iv) three tests in two or more populations, where two tests are correlated but jointly independent of the third test. For each scenario, we describe a Bayesian model that incorporates parameters of interest. The WinBUGS code used to fit each model, which is available at http://www.epi.ucdavis.edu/diagnos-tictests/, can be altered readily to conform to different data.
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                Author and article information

                Contributors
                Journal
                Int J Parasitol
                Int. J. Parasitol
                International Journal for Parasitology
                Elsevier Science
                0020-7519
                1879-0135
                01 October 2014
                01 October 2014
                : 44
                : 11
                : 765-774
                Affiliations
                Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, WC1E 7HT London, United Kingdom
                Author notes
                [* ]Corresponding author. Tel.: +44 (0)20 7927 2583. birgit.nikolay@ 123456lshtm.ac.uk
                Article
                S0020-7519(14)00143-X
                10.1016/j.ijpara.2014.05.009
                4186778
                24992655
                2fc19da3-9bbd-4b00-a1f3-c582181b5d15
                © 2014 The Authors
                History
                : 19 March 2014
                : 19 May 2014
                : 20 May 2014
                Categories
                Article

                Parasitology
                soil transmitted helminths,diagnostics,meta-analysis,latent class analysis
                Parasitology
                soil transmitted helminths, diagnostics, meta-analysis, latent class analysis

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