{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T03:01:32Z","timestamp":1789441292044,"version":"build-2803163510"},"reference-count":26,"publisher":"Public Library of Science (PLoS)","issue":"4","license":[{"start":{"date-parts":[[2025,4,1]],"date-time":"2025-04-01T00:00:00Z","timestamp":1743465600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:sec id=\"sec023\">\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Conducting meta-analyses on ordinal outcome data is more complex than on binary or continuous data. This study aims to summarise the current biomedical literature on meta-analytical methods for ordinal outcomes and attempts to reproduce the results of previous studies.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec024\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A systematic search was conducted in three databases, MEDLINE, EMBASE, and PsycINFO, from inception to 05\/05\/2024. Forward and backward citation searches were also performed. The screening was conducted in two phases using Covidence software. Studies were included if they reported or compared methods for meta-analysis of ordinal outcomes in clinical interventional studies. Relevant studies were summarised and discussed. If sufficient data for methods comparison were available, either in the retrieved reports or after contacting the authors, an attempt at reproducible research was made.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec025\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>333 records were screened, yielding four methodological studies that met the inclusion criteria. These studies addressed meta-analytical methods for ordinal scales ranging from 5 to 20 ordered categories. The three primary approaches identified were (1) ordinal models (proportional odds and generalised odds), (2) binary models (dichotomisation of ordinal scales), and (3) continuous models (treating ordinal scales as continuous variables). None of the included studies provided a comprehensive comparison of all three approaches. Two studies compared different proportional odds models; one compared binary with proportional odds, but the full results were not published, and one compared continuous and generalised odds models using simulated data with one scenario. The latter study allowed for reproducibility, but our analysis produced different results, and attempts to clarify the discrepancy with the authors were unsuccessful.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec026\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>A significant knowledge gap exists regarding the optimal meta-analytical method for ordinal outcomes in clinical interventional studies. Further methodological research is required to establish a robust evidence base for choosing the most appropriate approach.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1371\/journal.pone.0313720","type":"journal-article","created":{"date-parts":[[2025,4,1]],"date-time":"2025-04-01T16:43:41Z","timestamp":1743525821000},"page":"e0313720","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":3,"title":["Meta-analytical approaches to ordinal outcome data in clinical interventional studies: A scoping review with reproducible research"],"prefix":"10.1371","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2614-610X","authenticated-orcid":true,"given":"Ali","family":"Mulhem","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2025,4,1]]},"reference":[{"key":"pone.0313720.ref001","volume-title":"Cochrane Handbook for Systematic Reviews of Interventions version 6","author":"JJ Deeks","year":"2022"},{"issue":"5","key":"pone.0313720.ref002","doi-asserted-by":"crossref","first-page":"625","DOI":"10.1002\/sim.2934","article-title":"Recent developments in meta-analysis","volume":"27","author":"AJ Sutton","year":"2008","journal-title":"Stat Med"},{"key":"pone.0313720.ref003","doi-asserted-by":"crossref","DOI":"10.1002\/9781119558378","volume-title":"Introduction to meta-analysis.","author":"M Borenstein","year":"2021"},{"key":"pone.0313720.ref004","volume-title":"Analysis of ordinal categorical data","author":"A Agresti","year":"2014"},{"issue":"2","key":"pone.0313720.ref005","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1097\/00006199-199003000-00019","article-title":"Treating ordinal scales as interval scales: an attempt to resolve the controversy","volume":"39","author":"TR Knapp","year":"1990","journal-title":"Nurs Res"},{"key":"pone.0313720.ref006","doi-asserted-by":"crossref","DOI":"10.1101\/2024.06.24.24309421","article-title":"Opportunities for more powerful statistical analyses of ordinal scales: a scoping review of neurological trials","author":"Y Long","year":"2024"},{"issue":"1","key":"pone.0313720.ref007","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1186\/s13063-024-08072-2","article-title":"Statistical analyses of ordinal outcomes in randomised controlled trials: a scoping review","volume":"25","author":"CJ Selman","year":"2024","journal-title":"Trials"},{"issue":"1","key":"pone.0313720.ref008","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1186\/s13643-021-01626-4","article-title":"The PRISMA 2020 statement: an updated guideline for reporting systematic reviews","volume":"10","author":"MJ Page","year":"2021","journal-title":"Syst Rev"},{"issue":"7","key":"pone.0313720.ref009","doi-asserted-by":"crossref","first-page":"467","DOI":"10.7326\/M18-0850","article-title":"PRISMA Extension for Scoping Reviews (PRISMA-ScR): checklist and explanation","volume":"169","author":"AC Tricco","year":"2018","journal-title":"Ann Intern Med"},{"issue":"1","key":"pone.0313720.ref010","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1186\/s12874-020-01107-7","article-title":"A tutorial on methodological studies: the what, when, how and why","volume":"20","author":"L Mbuagbaw","year":"2020","journal-title":"BMC Med Res Methodol"},{"issue":"2","key":"pone.0313720.ref011","doi-asserted-by":"crossref","first-page":"68","DOI":"10.5596\/c14-016","article-title":"Product review: covidence (systematic review software)","volume":"35","author":"J Babineau","year":"2014","journal-title":"J Can Health Libr Assoc"},{"key":"pone.0313720.ref012"},{"key":"pone.0313720.ref013","unstructured":"Stata Statistical Software: Release 18."},{"issue":"S1","key":"pone.0313720.ref014","doi-asserted-by":"crossref","DOI":"10.1186\/1745-6215-14-S1-P120","article-title":"Practical methods for ordinal data meta-analysis in stroke","volume":"14","author":"A Krishan","year":"2013","journal-title":"Trials"},{"issue":"23\u201324","key":"pone.0313720.ref015","doi-asserted-by":"crossref","first-page":"2503","DOI":"10.1002\/sim.4780132313","article-title":"A meta-analysis of clinical trials involving different classifications of response into ordered categories","volume":"13","author":"A Whitehead","year":"1994","journal-title":"Stat Med"},{"issue":"15","key":"pone.0313720.ref016","doi-asserted-by":"crossref","first-page":"2243","DOI":"10.1002\/sim.919","article-title":"Meta-analysis of ordinal outcomes using individual patient data","volume":"20","author":"A Whitehead","year":"2001","journal-title":"Stat Med"},{"issue":"12","key":"pone.0313720.ref017","doi-asserted-by":"crossref","first-page":"e0145580","DOI":"10.1371\/journal.pone.0145580","article-title":"The missing medians: exclusion of ordinal data from meta-analyses","volume":"10","author":"TB Cumming","year":"2015","journal-title":"PLoS One"},{"issue":"11","key":"pone.0313720.ref018","doi-asserted-by":"crossref","first-page":"1444","DOI":"10.1212\/WNL.33.11.1444","article-title":"Rating neurologic impairment in multiple sclerosis: an expanded disability status scale (EDSS)","volume":"33","author":"JF Kurtzke","year":"1983","journal-title":"Neurology"},{"issue":"2","key":"pone.0313720.ref019","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1212\/WNL.45.2.251","article-title":"Disease steps in multiple sclerosis: a simple approach to evaluate disease progression","volume":"45","author":"MJ Hohol","year":"1995","journal-title":"Neurology"},{"issue":"7","key":"pone.0313720.ref020","first-page":"28","article-title":"The clinical global impressions scale: applying a research tool in clinical practice","volume":"4","author":"J Busner","year":"2007","journal-title":"Psychiatry (Edgmont)"},{"issue":"5","key":"pone.0313720.ref021","doi-asserted-by":"crossref","first-page":"604","DOI":"10.1161\/01.STR.19.5.604","article-title":"Interobserver agreement for the assessment of handicap in stroke patients","volume":"19","author":"JC van Swieten","year":"1988","journal-title":"Stroke"},{"key":"pone.0313720.ref022","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1201\/9781003194156-7","article-title":"Proportional odds logistic regression for ordered category outcomes.","volume-title":"Handbook of Regression Modeling in People Analytics","author":"K McNulty","year":"2021"},{"issue":"1","key":"pone.0313720.ref023","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1186\/s13643-024-02537-w","article-title":"Network meta-analysis for an ordinal outcome when outcome categorization varies across trials","volume":"13","author":"P Morris","year":"2024","journal-title":"Syst Rev"},{"issue":"1","key":"pone.0313720.ref024","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1186\/s13063-016-1369-2","article-title":"Sharing raw data from clinical trials: what progress since we first asked \u201cWhose data set is it anyway?\u201d","volume":"17","author":"AJ Vickers","year":"2016","journal-title":"Trials"},{"issue":"6519","key":"pone.0313720.ref025","doi-asserted-by":"crossref","first-page":"537","DOI":"10.1136\/bmj.292.6519.537","article-title":"Ordinal scale and statistics in medical research","volume":"292","author":"M Forrest","year":"1986","journal-title":"Br Med J (Clin Res Ed)"},{"issue":"3","key":"pone.0313720.ref026","doi-asserted-by":"crossref","first-page":"204","DOI":"10.1007\/s10519-020-10031-x","article-title":"Best practices for binary and ordinal data analyses","volume":"51","author":"B Verhulst","year":"2021","journal-title":"Behav Genet"}],"container-title":["PLOS ONE"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0313720","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,4,1]],"date-time":"2025-04-01T16:44:56Z","timestamp":1743525896000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0313720"}},"subtitle":[],"editor":[{"given":"Yibeltal Alemu","family":"Bekele","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2025,4,1]]},"references-count":26,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2025,4,1]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0313720","relation":{"has-preprint":[{"id-type":"doi","id":"10.1101\/2024.10.31.24316540","asserted-by":"object"}]},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,4,1]]}}}