{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,29]],"date-time":"2026-10-29T18:53:10Z","timestamp":1793299990191,"version":"4.5.0"},"reference-count":27,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2026,7,19]],"date-time":"2026-07-19T00:00:00Z","timestamp":1784419200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,7,19]],"date-time":"2026-07-19T00:00:00Z","timestamp":1784419200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Veterinary Ophthalmology"],"published-print":{"date-parts":[[2026,9]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>Cohen's kappa is widely used to measure rater agreement on binary outcomes and performs well when outcome prevalence is relatively balanced. This paper aims to explain the challenges encountered with Cohen's kappa, and to provide guidance to veterinary ophthalmologists on the usage and interpretation of kappa values.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Animals Studied<\/jats:title>\n                    <jats:p>Article based on an existing dataset in which two examiners graded iridocorneal angle abnormalities in 60 client\u2010owned dogs during pre\u2010breeding examinations.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Procedure<\/jats:title>\n                    <jats:p>Following the 2022 ECVO\u2010HED (European College of Veterinary Ophthalmology\u2014Hereditary Eye Diseases) gonioscopy grading scheme and its general recommendations, eyes were classified into two categories\u2014\u201cbreeding\u2010YES\u201d (not affected, mildly or moderately affected) or \u201cbreeding\u2010NO\u201d (severely affected). Inter\u2010examiner agreement was separately assessed for real (60 left and 58 right eyes) and simulated data (manually balanced left eye dataset with unchanged agreement between examiners).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>While the two examiners classified 52\/60 left and 51\/58 right eyes into the \u201cbreeding\u2010YES\u201d category, they disagreed on 7\/60 left and 1\/58 right eyes, with resulting kappa values of 0.18 and 0.91 for the left and right eyes, respectively. After balancing the data, with both examiners classifying 27\/60 left eyes into the \u201cbreeding\u2010yes\u201d category, but still disagreeing on 7\/60 eyes, the kappa value increased to 0.77.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Readers should be cautious when comparing kappa values across studies with different underlying prevalence and bias. Under non\u2010ideal data distribution,\u00a0additional statistical indices like prevalence\u2010 and bias index, prevalence\u2010and\u2010bias\u2010adjusted kappa (PABAK), and maxKappa, do not replace Cohen's kappa, but assist in interpreting it.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/vop.70208","type":"journal-article","created":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T03:50:56Z","timestamp":1784519456000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Challenges and Misinterpretations of Cohen's Kappa in Agreement Studies in Ophthalmology"],"prefix":"10.1111","volume":"29","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4507-7581","authenticated-orcid":false,"given":"Malwina Ewa","family":"Kowalska","sequence":"first","affiliation":[{"name":"Ophthalmology Section, Vetsuisse Faculty University of Zurich  Zurich Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-1185-053X","authenticated-orcid":false,"given":"Niklas","family":"Holz","sequence":"additional","affiliation":[{"name":"Ophthalmology Section, Vetsuisse Faculty University of Zurich  Zurich Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8782-7144","authenticated-orcid":false,"given":"Simon Anton","family":"Pot","sequence":"additional","affiliation":[{"name":"Ophthalmology Section, Vetsuisse Faculty University of Zurich  Zurich Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-5873-2866","authenticated-orcid":false,"given":"Antonella","family":"Rampazzo","sequence":"additional","affiliation":[{"name":"Ophthalmology Section, Vetsuisse Faculty University of Zurich  Zurich Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5757-5708","authenticated-orcid":false,"given":"Sonja","family":"Hartnack","sequence":"additional","affiliation":[{"name":"Section of Epidemiology, Vetsuisse Faculty University of Zurich  Zurich Switzerland"},{"name":"Centre for Veterinary Systems Transformation and Sustainability, Clinical Department for Farm Animals and Food System Science University of Veterinary Medicine Vienna  Vienna Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,7,19]]},"reference":[{"key":"e_1_2_13_2_1","doi-asserted-by":"publisher","DOI":"10.1177\/001316446002000104"},{"key":"e_1_2_13_3_1","doi-asserted-by":"publisher","DOI":"10.1177\/001316448104100307"},{"key":"e_1_2_13_4_1","doi-asserted-by":"publisher","DOI":"10.1093\/aje\/126.2.161"},{"key":"e_1_2_13_5_1","doi-asserted-by":"publisher","DOI":"10.2307\/2529310"},{"key":"e_1_2_13_6_1","doi-asserted-by":"publisher","DOI":"10.1201\/9780429258589"},{"key":"e_1_2_13_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/0471445428"},{"key":"e_1_2_13_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jcrimjus.2017.12.010"},{"key":"e_1_2_13_9_1","doi-asserted-by":"publisher","DOI":"10.1037\/h0026714"},{"key":"e_1_2_13_10_1","unstructured":"ECVO HED Committee \u201cECVO Manual for Presumed Inherited Eye Diseases in Dogs and Cats \u201d(2013) https:\/\/www.ecvo.eu\/hereditary\u2010eye\u2010diseases\/ecvo\u2010manual.html."},{"key":"e_1_2_13_11_1","doi-asserted-by":"publisher","DOI":"10.1111\/vop.13292"},{"key":"e_1_2_13_12_1","doi-asserted-by":"publisher","DOI":"10.1038\/sdata.2016.18"},{"key":"e_1_2_13_13_1","first-page":"4.4.1","volume-title":"R: A Language and Environment for Statistical Computing","author":"R Core Team","year":"2023"},{"key":"e_1_2_13_14_1","unstructured":"M.StevensonandE.Sergeant \u201cepiR: Tools for the Analysis of Epidemiological Data \u201d(2024) https:\/\/CRAN.R\u2010project.org\/package=epiR."},{"key":"e_1_2_13_15_1","doi-asserted-by":"publisher","DOI":"10.1093\/ptj\/85.3.257"},{"key":"e_1_2_13_16_1","first-page":"423","volume-title":"Bias, Prevalence and Kappa","author":"Byrt T.","year":"1993"},{"key":"e_1_2_13_17_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.prevetmed.2006.02.004"},{"key":"e_1_2_13_18_1","doi-asserted-by":"publisher","DOI":"10.1186\/1471\u20102288\u20109\u20105"},{"key":"e_1_2_13_19_1","doi-asserted-by":"publisher","DOI":"10.1177\/096228029200100202"},{"key":"e_1_2_13_20_1","volume-title":"Veterinary Epidemiologic Research","author":"Dohoo I.","year":"2014"},{"key":"e_1_2_13_21_1","volume-title":"High Agreement but Low Kappa: I. 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