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. 2021:28:39.
doi: 10.1051/parasite/2021035. Epub 2021 Apr 26.

Anti-Toxoplasma IgG assays: What performances for what purpose? A systematic review

Florence Robert-Gangneux  1 , Hélène Guegan  1
Affiliations

Anti-Toxoplasma IgG assays: What performances for what purpose? A systematic review

Florence Robert-Gangneux et al. Parasite. 2021.

Abstract
in English, French

Chronic infection with Toxoplasma gondii is attested by the detection of specific anti-Toxoplasma IgG. A wide panel of serologic methods is currently marketed, and the most suitable method should be chosen according to the laboratory resources and the screened population. This systematic review of evaluation studies aimed at establishing an overview of the performances, i.e. sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of marketed anti-Toxoplasma IgG assays, and discussing their technical characteristics to guide further choice for routine diagnostic use. According to PRISMA guidelines, the search performed in PubMed and Web of Science databases recovered 826 studies, of which 17 were ultimately included. Twenty commercial anti-Toxoplasma IgG assays were evaluated, in comparison with an accepted reference method. Most of them were enzyme-immunoassays (EIAs, n = 12), followed by agglutination tests (n = 4), immunochromatographic tests (n = 3), and a Western-Blot assay (WB, n = 1). The mean sensitivity of IgG assays ranged from 89.7% to 100% for standard titers and from 13.4% to 99.2% for low IgG titers. A few studies pointed out the ability of some methods, especially WB to detect IgG early after primary infection. The specificity of IgG assays was generally high, ranging from 91.3% to 100%; and higher than 99% for most EIA assays. The PPV was not a discriminant indicator among methods, whereas significant disparities (87.5%-100%) were reported among NPVs, a key-parameter assessing the ability to definitively rule out a Toxoplasma infection in patients at-risk for opportunistic infections.

Title: Les tests pour la détection d’IgG anti-Toxoplasma : quelles performances pour quel usage ? Une revue systématique.

Abstract: L’infection chronique à Toxoplasma gondii est attestée par la détection d’IgG anti-Toxoplasma spécifiques. Un large panel de méthodes sérologiques est actuellement commercialisé, et le choix d’une méthode doit être adapté aux ressources du laboratoire ainsi qu’à la population ciblée. Cette revue systématique des études d’évaluation visait à établir une vue d’sensemble des performances, c’est-à-dire la sensibilité, la spécificité, la valeur prédictive positive (VPP) et la valeur prédictive négative (VPN) des kits commercialisés pour la détection d’IgG anti-Toxoplasma, et à discuter leurs caractéristiques techniques pour guider le choix pour un usage diagnostique de routine. Selon les directives PRISMA, la recherche effectuée dans les bases de données PubMed et Web of Science a permis de retrouver 826 études, dont 17 ont été définitivement incluses. Vingt dosages commerciaux d’IgG anti-Toxoplasma ont été évalués, en comparaison avec une méthode de référence. La plupart des tests étaient des méthodes de dosage immuno-enzymatique (n = 12), d’agglutination (n = 4), immunochromatographiques (n = 3) et de Western-Blot (n = 1). La sensibilité moyenne des dosages IgG variait de 89,7 à 100 % pour les titres standards et de 13,4 % à 99,2 % pour les faibles titres d’IgG. Quelques études ont souligné la capacité de certaines méthodes, en particulier le Western-Blot, à détecter les IgG au cours d’une primo-infection. La spécificité des tests IgG était généralement élevée, allant de 91,3 % à 100, et supérieure à 99 % pour la plupart des tests immuno-enzymatiques. La VPP n’était pas un indicateur discriminant entre les méthodes, alors que des disparités significatives (87,5 % à 100 %) ont été rapportées entre les VPN, un paramètre-clé reflétant la capacité d’un test à éliminer formellement une toxoplasmose chez les patients à risque d’infections opportunistes.

Keywords: Anti-Toxoplasma IgG; Diagnosis; Sensitivity; Serology; Specificity; Toxoplasmosis.

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Figures

Figure 1
Figure 1
Flow chart of article selection for review.
Figure 2
Figure 2
Positive predictive value (PPV) and negative predictive value (NPV) calculated for 10 anti-Toxoplasma IgG EIA assays (A, C) and 8 manual assays (B, D) included in the study.
See this image and copyright information in PMC

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