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A Meta-Analysis of Typhoid Diagnostic Accuracy Studies: A Recommendation to Adopt a Standardized Composite Reference.

Storey HL, Huang Y, Crudder C, Golden A, de los Santos T, Hawkins K - PLoS ONE (2015)

Bottom Line: Blood culture is most often used as the reference method to evaluate the accuracy of new typhoid tests; however, it is recognized to be an imperfect gold standard.In order to evaluate existing tests for use as a reference test or inclusion in a CRS, we performed a systematic review of the typhoid literature to include all index/reference test combinations observed.We described the landscape of comparisons performed, showed results of a meta-analysis on the accuracy of the more common combinations, and evaluated sources of variability based on study quality.

View Article: PubMed Central - PubMed

Affiliation: Diagnostics Program, PATH, Seattle, Washington, United States of America.

ABSTRACT
Novel typhoid diagnostics currently under development have the potential to improve clinical care, surveillance, and the disease burden estimates that support vaccine introduction. Blood culture is most often used as the reference method to evaluate the accuracy of new typhoid tests; however, it is recognized to be an imperfect gold standard. If no single gold standard test exists, use of a composite reference standard (CRS) can improve estimation of diagnostic accuracy. Numerous studies have used a CRS to evaluate new typhoid diagnostics; however, there is no consensus on an appropriate CRS. In order to evaluate existing tests for use as a reference test or inclusion in a CRS, we performed a systematic review of the typhoid literature to include all index/reference test combinations observed. We described the landscape of comparisons performed, showed results of a meta-analysis on the accuracy of the more common combinations, and evaluated sources of variability based on study quality. This wide-ranging meta-analysis suggests that no single test has sufficiently good performance but some existing diagnostics may be useful as part of a CRS. Additionally, based on findings from the meta-analysis and a constructed numerical example demonstrating the use of CRS, we proposed necessary criteria and potential components of a typhoid CRS to guide future recommendations. Agreement and adoption by all investigators of a standardized CRS is requisite, and would improve comparison of new diagnostics across independent studies, leading to the identification of a better reference test and improved confidence in prevalence estimates.

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PRISMA flowchart.Study flow depicting search strategy, inclusion/exclusion criteria, and summary of systematic review.
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pone.0142364.g001: PRISMA flowchart.Study flow depicting search strategy, inclusion/exclusion criteria, and summary of systematic review.

Mentions: We performed a review and meta-analysis using the PRISMA reporting guidelines (S1 Table) [11]. In May 2013, a detailed search strategy was designed to identify all papers in English that evaluated diagnostic tests for the detection of typhoid fever among humans. If papers considered typhoid fever to include Salmonella typhi and S. paratyphi A, the data were included as such in our review. The following databases were included: Pubmed, EMBASE, and ISI Web of Science (S2 Table). In all, 276 papers were identified from our searches (Fig 1). After reviewing the abstracts, 72 papers were excluded based on the following: had no original data (10), were not in English (13), had no abstract available (8), did not compare two diagnostic tests (28), were not related to typhoid (7), described single case studies (4), and no full paper was found (2). The remaining papers were reviewed in full (204), and further exclusions were made if two diagnostic tests were not evaluated that dichotomized result as positive or negative for typhoid fever (50), or sufficient data were not given to confidently infer all values of the contingency table (18). A diagnosis based on clinical indicators was considered a diagnostic test if classified as positive or negative. Additional papers were identified from references or collaborators (2). The search strategy was updated September 2013 and nine additional abstracts were identified, of which one paper was added to the study. In total, 413 index/reference comparisons from 139 papers were included in the meta-analysis (Fig 1) [12–181].


A Meta-Analysis of Typhoid Diagnostic Accuracy Studies: A Recommendation to Adopt a Standardized Composite Reference.

Storey HL, Huang Y, Crudder C, Golden A, de los Santos T, Hawkins K - PLoS ONE (2015)

PRISMA flowchart.Study flow depicting search strategy, inclusion/exclusion criteria, and summary of systematic review.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643909&req=5

pone.0142364.g001: PRISMA flowchart.Study flow depicting search strategy, inclusion/exclusion criteria, and summary of systematic review.
Mentions: We performed a review and meta-analysis using the PRISMA reporting guidelines (S1 Table) [11]. In May 2013, a detailed search strategy was designed to identify all papers in English that evaluated diagnostic tests for the detection of typhoid fever among humans. If papers considered typhoid fever to include Salmonella typhi and S. paratyphi A, the data were included as such in our review. The following databases were included: Pubmed, EMBASE, and ISI Web of Science (S2 Table). In all, 276 papers were identified from our searches (Fig 1). After reviewing the abstracts, 72 papers were excluded based on the following: had no original data (10), were not in English (13), had no abstract available (8), did not compare two diagnostic tests (28), were not related to typhoid (7), described single case studies (4), and no full paper was found (2). The remaining papers were reviewed in full (204), and further exclusions were made if two diagnostic tests were not evaluated that dichotomized result as positive or negative for typhoid fever (50), or sufficient data were not given to confidently infer all values of the contingency table (18). A diagnosis based on clinical indicators was considered a diagnostic test if classified as positive or negative. Additional papers were identified from references or collaborators (2). The search strategy was updated September 2013 and nine additional abstracts were identified, of which one paper was added to the study. In total, 413 index/reference comparisons from 139 papers were included in the meta-analysis (Fig 1) [12–181].

Bottom Line: Blood culture is most often used as the reference method to evaluate the accuracy of new typhoid tests; however, it is recognized to be an imperfect gold standard.In order to evaluate existing tests for use as a reference test or inclusion in a CRS, we performed a systematic review of the typhoid literature to include all index/reference test combinations observed.We described the landscape of comparisons performed, showed results of a meta-analysis on the accuracy of the more common combinations, and evaluated sources of variability based on study quality.

View Article: PubMed Central - PubMed

Affiliation: Diagnostics Program, PATH, Seattle, Washington, United States of America.

ABSTRACT
Novel typhoid diagnostics currently under development have the potential to improve clinical care, surveillance, and the disease burden estimates that support vaccine introduction. Blood culture is most often used as the reference method to evaluate the accuracy of new typhoid tests; however, it is recognized to be an imperfect gold standard. If no single gold standard test exists, use of a composite reference standard (CRS) can improve estimation of diagnostic accuracy. Numerous studies have used a CRS to evaluate new typhoid diagnostics; however, there is no consensus on an appropriate CRS. In order to evaluate existing tests for use as a reference test or inclusion in a CRS, we performed a systematic review of the typhoid literature to include all index/reference test combinations observed. We described the landscape of comparisons performed, showed results of a meta-analysis on the accuracy of the more common combinations, and evaluated sources of variability based on study quality. This wide-ranging meta-analysis suggests that no single test has sufficiently good performance but some existing diagnostics may be useful as part of a CRS. Additionally, based on findings from the meta-analysis and a constructed numerical example demonstrating the use of CRS, we proposed necessary criteria and potential components of a typhoid CRS to guide future recommendations. Agreement and adoption by all investigators of a standardized CRS is requisite, and would improve comparison of new diagnostics across independent studies, leading to the identification of a better reference test and improved confidence in prevalence estimates.

Show MeSH
Related in: MedlinePlus