Greenwood, DC

Zagari, RM

R. M. Zagari

D. C. Greenwood

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Alimentary Pharmacology & Therapeutics

Letter: questions regarding the diagnostic performance of serum assays for atrophic gastritis-Authors' reply

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This is a repository copy of Letter: questions regarding the diagnostic performance of serum assays for atrophic gastritis – authors’ reply.White Rose Research Online URL for this paper:http://eprints.whiterose.ac.uk/121456/Version: Accepted VersionArticle:Zagari, RM and Greenwood, DC (2017) Letter: questions regarding the diagnostic performance of serum assays for atrophic gastritis – authors’ reply. Alimentary Pharmacology and Therapeutics, 46 (11-12). pp. 1118-1119. ISSN 0269-2813 https://doi.org/10.1111/apt.14369© 2017 John Wiley & Sons Ltd. This is the peer reviewed version of the following article: Zagari, R. M. and Greenwood, D. C. (2017), Letter: questions regarding the diagnostic performance of serum assays for atrophic gastritis—Authors' reply. Aliment Pharmacol Ther, 46: 1118–1119. doi:10.1111/apt.14369, which has been published in final form at https://doi.org/10.1111/apt.14369. This article may be used for non-commercial purposes inaccordance with Wiley Terms and Conditions for Self-Archiving. Uploaded in accordance with the publisher's self-archiving policy.eprints@whiterose.ac.ukhttps://eprints.whiterose.ac.uk/Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Letter: questions regarding the diagnostic performance of serum assays for atrophic gastritis – authors’ reply  Rocco Maurizio Zagari1, Darren C. Greenwood 2.  1 Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy 2 Division of Biostatistics, University of Leeds, Leeds, UK     Corresponding author:  Prof. Rocco Maurizio Zagari,  Department of  Medical and Surgical Sciences, University of Bologna, Policlinico S. Orsola-Malpighi, Via Massarenti n. 9, 40138 Bologna, Italy.  Tel and Fax: +39 051 2144117 Email: roccomaurizio.zagari@unibo.it  Keywords: serum panel test, diagnosis, atrophic gastritis.  Word count: 378          Reply. We thank Dr. Graham for his interest (1) in our systematic review with meta-analysis on the diagnostic performance of the serum panel test for the diagnosis of atrophic gastritis (2).   His reminder that positive and negative predictive values depend on the prevalence of the condition in the population the test is being applied to is very relevant to the interpretation of the figures deriving from our meta-analysis of test accuracy studies conducted in different populations. This is one reason why we emphasized the median prevalence of atrophic gastritis in the studies being reviewed.  Dr. Graham will know that sensitivity and specificity do not provide information about the clinical impact of a test, i.e. how the test performs at a particular prevalence of disease; likelihood ratios do this by providing an estimate of positive and negative post-test probabilities of disease, but there is no evidence that likelihood ratios improve diagnostic decision making (3). A systematic review of test accuracy studies should help clinicians and health policy makers to decide whether to perform a test, and such a decision usually needs information also on the consequences coming from false negative or positive test results (3). Thus, in estimating predictive values we tried to provide further information on the clinical performance of the panel test.  Dr Graham's assertion that our interpretation of data is misleading may stem from a typographical error in our article, for which we apologize. In the discussion we stated that "the panel test would miss only nine subjects for every 100 with atrophic gastritis (negative predictive value = 91%)" when we meant to say "the panel test would miss the presence of atrophic gastritis in only nine subjects for every 100 with a negative test result (negative predictive value = 91%)". If Dr Graham had based his calculations on the numerical results we reported, he would have achieved the same results as us.  We thank Dr Graham for highlighting a typographical error in one sentence of our discussion, but the summary sensitivity, specificity, positive and negative predictive values quoted throughout the abstract, text, tables and figures are correct.   In conclusion, we believe that the results our meta-analysis can support the role of the combination of pepsinogen, gastrin-17 and anti-Helicobacter pylori antibodies serum assays in screening subjects for gastric cancer prevention.      References 1. Graham DY. Letter: questions regarding the diagnostic performance of serum assays for atrophic gastritis. Aliment Pharmacol Ther. 2017 in press. 2.  Zagari RM, Rabitti S, Greenwood DC, Eusebi LH, Vestito A, Bazzoli F. Systematic review with meta-analysis: diagnostic performance of the combination of pepsinogen, gastrin-17 and anti-Helicobacter pylori antibodies serum assays for the diagnosis of atrophic gastritis. Aliment Pharmacol Ther. 2017;00:1-11 3. Cochrane Collaboration, Diagnostic Test Accuracy Working Group: handbook for DTA reviews. http://srdta.cochrane.org/handbook-dta-reviews.  The authors’ declarations of personal and financial interests are unchanged from those in the original article (2)   

Letter: questions regarding the diagnostic performance of serum assays for atrophic gastritis – authors’ reply

Zagari, Rm

Greenwood, Dc

Archivio istituzionale della ricerca - Alma Mater Studiorum Università di Bologna

Letter: questions regarding the diagnostic performance of serum assays for atrophic gastritisâAuthors' reply

https://eprints.whiterose.ac.uk/121456/1/Reply%20to%20dr.%20Graham%20DCG.pdf

Letter: questions regarding the diagnostic performance of serum assays for atrophic gastritis – authors’ reply

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