Updating the PRISMA reporting guideline for network meta-analysis: a scoping review

Updating the PRISMA reporting guideline for network meta-analysis: a scoping review | medRxiv /* */ /* */ <!-- <!-- /*! * yepnope1.5.4 * (c) WTFPL, GPLv2 */ (function(a,b,c){function d(a){return"[object Function]"==o.call(a)}function e(a){return"string"==typeof a}function f(){}function g(a){return!a||"loaded"==a||"complete"==a||"uninitialized"==a}function h(){var a=p.shift();q=1,a?a.t?m(function(){("c"==a.t?B.injectCss:B.injectJs)(a.s,0,a.a,a.x,a.e,1)},0):(a(),h()):q=0}function i(a,c,d,e,f,i,j){function k(b){if(!o&&g(l.readyState)&&(u.r=o=1,!q&&h(),l.onload=l.onreadystatechange=null,b)){"img"!=a&&m(function(){t.removeChild(l)},50);for(var d in y[c])y[c].hasOwnProperty(d)&&y[c][d].onload()}}var j=j||B.errorTimeout,l=b.createElement(a),o=0,r=0,u={t:d,s:c,e:f,a:i,x:j};1===y[c]&&(r=1,y[c]=[]),"object"==a?l.data=c:(l.src=c,l.type=a),l.width=l.height="0",l.onerror=l.onload=l.onreadystatechange=function(){k.call(this,r)},p.splice(e,0,u),"img"!=a&&(r||2===y[c]?(t.insertBefore(l,s?null:n),m(k,j)):y[c].push(l))}function j(a,b,c,d,f){return q=0,b=b||"j",e(a)?i("c"==b?v:u,a,b,this.i++,c,d,f):(p.splice(this.i++,0,a),1==p.length&&h()),this}function k(){var a=B;return a.loader={load:j,i:0},a}var l=b.documentElement,m=a.setTimeout,n=b.getElementsByTagName("script")[0],o={}.toString,p=[],q=0,r="MozAppearance"in l.style,s=r&&!!b.createRange().compareNode,t=s?l:n.parentNode,l=a.opera&&"[object Opera]"==o.call(a.opera),l=!!b.attachEvent&&!l,u=r?"object":l?"script":"img",v=l?"script":u,w=Array.isArray||function(a){return"[object Array]"==o.call(a)},x=[],y={},z={timeout:function(a,b){return b.length&&(a.timeout=b[0]),a}},A,B;B=function(a){function b(a){var a=a.split("!"),b=x.length,c=a.pop(),d=a.length,c={url:c,origUrl:c,prefixes:a},e,f,g;for(f=0;f<d;f++)g=a[f].split("="),(e=z[g.shift()])&&(c=e(c,g));for(f=0;f<b;f++)c=x[f](c);return c}function g(a,e,f,g,h){var i=b(a),j=i.autoCallback;i.url.split(".").pop().split("?").shift(),i.bypass||(e&&(e=d(e)?e:e[a]||e[g]||e[a.split("/").pop().split("?")[0]]),i.instead?i.instead(a,e,f,g,h):(y[i.url]?i.noexec=!0:y[i.url]=1,f.load(i.url,i.forceCSS||!i.forceJS&&"css"==i.url.split(".").pop().split("?").shift()?"c":c,i.noexec,i.attrs,i.timeout),(d(e)||d(j))&&f.load(function(){k(),e&&e(i.origUrl,h,g),j&&j(i.origUrl,h,g),y[i.url]=2})))}function h(a,b){function c(a,c){if(a){if(e(a))c||(j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}),g(a,j,b,0,h);else if(Object(a)===a)for(n in m=function(){var b=0,c;for(c in a)a.hasOwnProperty(c)&&b++;return b}(),a)a.hasOwnProperty(n)&&(!c&&!--m&&(d(j)?j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}:j[n]=function(a){return function(){var b=[].slice.call(arguments);a&&a.apply(this,b),l()}}(k[n])),g(a[n],j,b,n,h))}else!c&&l()}var h=!!a.test,i=a.load||a.both,j=a.callback||f,k=j,l=a.complete||f,m,n;c(h?a.yep:a.nope,!!i),i&&c(i)}var i,j,l=this.yepnope.loader;if(e(a))g(a,0,l,0);else if(w(a))for(i=0;i (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0];var j=d.createElement(s);var dl=l!='dataLayer'?'&l='+l:'';j.src='//www.googletagmanager.com/gtm.js?id='+i+dl;j.type='text/javascript';j.async=true;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-P4HH5NV'); Skip to main content Home About Submit ALERTS / RSS Search for this keyword Advanced Search Updating the PRISMA reporting guideline for network meta-analysis: a scoping review View ORCID Profile Areti Angeliki Veroniki , Andrea C. Tricco , Daniella Rangira , Joanne E. McKenzie , Tianjing Li , Sharon E. Straus , Maureen Smith , Ferrán Catalá-López , Dianna Wolfe , Vera Nincic , Menelaos Konstantinidis , Juan Franco , David Tovey , Sai Surabi Thirugnanasampanthar , Jasmeen Dourka , Rachel Warren , George Wells , Adrienne Stevens , Brian Hutton doi: https://doi.org/10.1101/2025.02.06.25321746 Areti Angeliki Veroniki 1 Knowledge Translation Program, Li Ka Shing Knowledge Institute, St. Michael’s Hospital , Unity Health Toronto, 209 Victoria Street, Toronto, ON, Canada 2 Institute for Health Policy, Management, and Evaluation, University of Toronto , 155 College Street, Toronto, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Areti Angeliki Veroniki For correspondence: a.veroniki{at}utoronto.ca Areti-Angeliki.Veroniki{at}unityhealth.to Andrea C. Tricco 1 Knowledge Translation Program, Li Ka Shing Knowledge Institute, St. Michael’s Hospital , Unity Health Toronto, 209 Victoria Street, Toronto, ON, Canada 3 Epidemiology Division & Institute of Health Policy, Management, and Evaluation, Dalla Lana School of Public Health, University of Toronto , Toronto, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Daniella Rangira 1 Knowledge Translation Program, Li Ka Shing Knowledge Institute, St. Michael’s Hospital , Unity Health Toronto, 209 Victoria Street, Toronto, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Joanne E. McKenzie 4 Methods in Evidence Synthesis Unit, School of Public Health and Preventive Medicine, Monash University , Melbourne, Australia Find this author on Google Scholar Find this author on PubMed Search for this author on this site Tianjing Li 5 Department of Ophthalmology, School of Medicine, University of Colorado Denver , Denver, Colorado, United States Find this author on Google Scholar Find this author on PubMed Search for this author on this site Sharon E. Straus 1 Knowledge Translation Program, Li Ka Shing Knowledge Institute, St. Michael’s Hospital , Unity Health Toronto, 209 Victoria Street, Toronto, ON, Canada 2 Institute for Health Policy, Management, and Evaluation, University of Toronto , 155 College Street, Toronto, ON, Canada 6 Department of Geriatric Medicine, University of Toronto , Toronto, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Maureen Smith 7 Patient Partner, SPOR Evidence Alliance , Ottawa, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Ferrán Catalá-López 8 Clinical Epidemiology Program, Ottawa Hospital Research Institute , Ottawa, ON, Canada 9 Centre for Human and Social Sciences (CCHS), Institute of Public Goods and Policies (IPP), Spanish National Research Council (CSIC) , Madrid, Spain Find this author on Google Scholar Find this author on PubMed Search for this author on this site Dianna Wolfe 10 Methodological and Implementation Research Program, Ottawa Hospital Research Institute , Ottawa, Ontario Find this author on Google Scholar Find this author on PubMed Search for this author on this site Vera Nincic 1 Knowledge Translation Program, Li Ka Shing Knowledge Institute, St. Michael’s Hospital , Unity Health Toronto, 209 Victoria Street, Toronto, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Menelaos Konstantinidis 1 Knowledge Translation Program, Li Ka Shing Knowledge Institute, St. Michael’s Hospital , Unity Health Toronto, 209 Victoria Street, Toronto, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Juan Franco 11 Institute of General Practice, Medical Faculty of the Heinrich-Heine-University Düsseldorf , Düsseldorf, Germany Find this author on Google Scholar Find this author on PubMed Search for this author on this site David Tovey 12 Journal of Clinical Epidemiology , Sussex, United Kingdom Find this author on Google Scholar Find this author on PubMed Search for this author on this site Sai Surabi Thirugnanasampanthar 1 Knowledge Translation Program, Li Ka Shing Knowledge Institute, St. Michael’s Hospital , Unity Health Toronto, 209 Victoria Street, Toronto, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Jasmeen Dourka 1 Knowledge Translation Program, Li Ka Shing Knowledge Institute, St. Michael’s Hospital , Unity Health Toronto, 209 Victoria Street, Toronto, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Rachel Warren 1 Knowledge Translation Program, Li Ka Shing Knowledge Institute, St. Michael’s Hospital , Unity Health Toronto, 209 Victoria Street, Toronto, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site George Wells 13 Cardiovascular Research Methods Centre, University of Ottawa Heart Institute 14 School of Epidemiology and Public Health, University of Ottawa 15 Department of Medicine, University of Ottawa Find this author on Google Scholar Find this author on PubMed Search for this author on this site Adrienne Stevens 16 Centre for Immunization Programs, Infectious Diseases & Vaccination Programs Branch , Public Health Agency of Canada , Ottawa, ON, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Brian Hutton 10 Methodological and Implementation Research Program, Ottawa Hospital Research Institute , Ottawa, Ontario 17 Ottawa University School of Epidemiology and Public Health , Ottawa, Ontario Find this author on Google Scholar Find this author on PubMed Search for this author on this site Abstract Full Text Info/History Metrics Supplementary material Data/Code Preview PDF STANDFIRST This scoping review represents the initial step in updating the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) extension for network meta-analysis (NMA) to improve the usability and relevance of systematic reviews with NMA for diverse audiences. The update will address gaps in reporting, such as documenting methods for assessing NMA homogeneity and transitivity, defining intervention nodes, and considering advances in statistical modeling. It will align with PRISMA 2020 and incorporate input from diverse knowledge users, including patients and the public. This scoping review included 61 studies, comprising 23 guidance documents and 38 overviews of reviews evaluating the completeness of reporting and methodological quality of published NMAs. We identified 37 additional NMA items for inclusion in the next step—the Delphi survey. Building on a 2014 scoping review by our team, we incorporated recent studies to inform the PRISMA-NMA update, adhering to established standards for guideline development. SUMMARY POINTS Network meta-analyses (NMAs) are increasingly prominent in evidence synthesis, but their methodological transparency and reporting completeness remain inconsistent, which affects the reliability of results. This scoping review highlights the need to update PRISMA-NMA to address evolving methodologies (e.g., component NMA) and reporting challenges to improve accessibility and utility of NMA findings. The review underscores progress and gaps in NMA reporting since the 2015 PRISMA-NMA extension, focusing on synthesis methods, homogeneity, consistency and transitivity assessments, and network geometry. Key recommendations, such as defining pre-specified nodes, specifying statistical methods, and addressing competing interests, were often overlooked in NMA reporting, but addressing these gaps could enhance transparency, reproducibility, and trust in NMA results. INTRODUCTION Systematic reviews are fundamental to evidence-informed practice and policy, underscoring the need for their accurate, complete, and transparent reporting. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement provides reporting 1 recommendations to facilitate clarity, transparency, and reproducibility of systematic reviews. A number of extensions to PRISMA have been developed for particular review questions (e.g., diagnostic test accuracy), types of reviews (e.g., scoping reviews), or particular methods. An example of the latter is the PRISMA extension for network meta-analysis (NMA), published in 2015, 2 which focuses on systematic reviews with NMAs. NMA allows the synthesis of evidence about the effect of multiple interventions in a single model, enabling comparisons of interventions that may plausibly be considered in specific contexts by incorporating indirect evidence alongside direct evidence. NMAs have revolutionized evidence synthesis and clinical decision-making across various fields 3 – 8 over the past two decades, and have been adopted by agencies such as the National Institute for Health and Care Excellence (NICE), the Canada Drug Agency (CDA; formerly CADTH 9 ), the National Health Service (NHS), and the World Health Organization (WHO) to inform health policies, cost-effectiveness analyses, and health technology assessments. 9 – 12 The update of the 2009 PRISMA Statement in 2020, 1 evidence of the need for improved reporting of systematic reviews with NMA and the continued evolution of NMA methodologies, 13 – 21 provides the impetuses for updating PRISMA-NMA. The update of PRISMA-NMA aims to enhance the usability and relevance of systematic reviews that include NMAs for diverse audiences. Specifically, this update will address incompletely reported items (e.g., documentation of methods and findings for assessing homogeneity and similarity of intervention comparisons, and transparent synopsis of efforts to define intervention nodes), and incorporate advances in statistical modeling. Also, this update will provide an improved alignment with the updated PRISMA 2020 and involvement of diverse knowledge users— including patients and the public—throughout the update process to ensure new end-user perspectives are integrated. As a first step in the process to update the PRISMA-NMA extension, we aimed to identify potential items for inclusion by undertaking a scoping review of studies evaluating the completeness of reporting and methodological quality of NMAs. We updated a 2014 scoping review performed by members of the research team 22 to identify additional, more recent studies to inform the PRISMA-NMA extension update. 2 The identified items will form the basis of the next step in the process – the Delphi survey ( Figure 1 ). This process aligns with guidance for the development of reporting guidelines in health. 23 Download figure Open in new tab Figure 1. Flow diagram illustrating the individual steps involved in the updated PRISMA-NMA process. METHODS Protocol The 2020 JBI (formerly Joanna Briggs Institute) methodological guidelines for scoping reviews were used to guide the methods of this scoping review 24 and the PRISMA extension for scoping reviews was used to guide the reporting of this review. 25 The methods for this study were drafted with input provided by evidence synthesis experts and knowledge users, including a patient partner (MS). We published our study protocol in the JBI 26 and registered it with the Open Science Framework at https://osf.io/7bkwy . Any protocol deviations are mentioned in Appendix 1. A lay summary of this study, prepared by our patient partner (MS), is provided in Appendix 2. Literature search We updated our previously developed literature search 22 based on feedback from the steering committee composed of international researchers with at least ten years of experience in systematic reviews with NMA and experience in the development of reporting guidelines for studies in health (AAV, ACT, JEM, TL, SES, BH) and a patient partner with extensive experience in patient engagement in systematic reviews with NMA (MS). The literature search was developed by an experienced librarian and was peer-reviewed by another librarian using the Peer Review of Electronic Search Strategies (PRESS) Checklist (see Appendix 3 for literature search). 27 Multiple databases were searched including MEDLINE, EMBASE, CINAHL, and The Cochrane Library from inception until December 11, 2023. We searched for unpublished literature based upon CDA Grey Matters guidance on December 13, 2023. 9 We searched Google and a selection of organizational websites (Agency for Healthcare Research and Quality [AHRQ], Canadian Institute of Health Research [CIHR], CDA, EQUATOR, Guidelines International Network, IQWiG [Institute for Quality and Efficiency in Health Care] in Germany, JBI, NICE, and PRISMA). The literature search was supplemented by reviewing reference lists of the included studies, as well as by a key article 28 identified by the steering committee. Reference scanning was done using Citation Chaser. 29 The search strategy was not limited by study design or language. Eligibility Criteria We included any study design that offered reporting guidance or evaluated completeness of reporting pertaining to systematic reviews that include NMAs; studies assessing risk of bias and methodological quality relevant to NMA; and editorial guidelines or tutorials that described items related to reporting completeness of NMAs. 30 Updates of studies were categorized as companion reports while the initially published paper was considered the main paper in the review. We excluded papers that were unrelated to NMA, did not focus on evaluating or providing reporting guidance, or were published before August 2013, as this was the last search date in the previous scoping review. 25 Study Selection We used the systematic review software platform Synthesi.SR 31 for screening. To ensure reliability, all reviewers completed a pilot test on 50 citations at level one (titles and abstracts) and 25 articles at level two (full-text papers) before screening, independently. After achieving high agreement at level one (88% in a single pilot test) and level two (84% after two pilot tests), team members (FCL, JD, MK, VN, RW, DW, AAV) independently screened all papers in duplicate (see Appendix 4 and 5 for screening guidance). Discrepancies were resolved by discussion with a third investigator (SST, AAV). We translated non-English articles using the DeepL Translate tool 32 or with the help of team members. We summarised the search and selection process in a PRISMA 2020 flow diagram. 1 The list of excluded study post-level two screening with reasoning is provided in Appendix 6. Data extraction Data extraction was performed independently and in duplicate by team members (FCL, JD, MK, VN, RW, DW, AAV, and BH) using a standardized Excel form co-created by the steering committee and reviewers (see Appendix 7 for extraction guidance). We did not combine the results from the studies included in the previous scoping review, 22 given that these already informed the development of the original PRISMA-NMA reporting guideline. 2 We developed a new form, based on the previous review, 22 with categories from which items were extracted: study characteristics (e.g., first author, year of publication, article source, study design [i.e. guidance document or overview of reviews]), study type (e.g., reporting or methodological quality in NMA), funding and funding source (e.g. public, industry, or mixed), reported objectives, inclusion criteria, number of NMAs included (in overviews of reviews [i.e., a study that assesses the reporting quality of a sample of NMAs]), timeframe of assessed literature, conflicts of interest, reporting/methodological guideline used, authors’ conclusions, and the authors’ recommendations as to which items should be reported. Prior to data extraction, we conducted a calibration exercise on a random sample of five included articles and modified the form according to feedback from the reviewers, steering committee, and our patient partner (MS). Data extraction began when we reached a high level of agreement (89% in a single pilot test). During this process our aim was to be overly inclusive and to capture as many details as possible, even if these were relevant only to the core PRISMA 2020. 1 Results from in duplicate data extraction were combined and summarized for each paper by two team members (DR, SST) to comprehensively organize key findings. Then, two team members (DR, AAV) reviewed, combined identical items, and refined wording of the extracted items for clarity. The full list of items was organized according to the broader categories of PRISMA-NMA and PRISMA 2020 statement sections (i.e., Title, Abstract, Introduction, Methods, Results, Discussion, and Other information) and sub-categories (e.g., in the Methods category these were: Eligibility Criteria, Information Sources, Search Strategy, Selection Process, Data Collection, Data Items, Geometry of the Network, Study Risk of Bias Assessment, Effect Measures, Synthesis Methods, Assessment of Inconsistency, Reporting Bias Assessment, and Certainty Assessment). The final list of items was refined according to its relevance to the PRISMA-NMA or the core PRISMA 2020 reporting guideline, with additional input from the steering committee. Data synthesis and analysis We present study characteristics and items suggested by authors across all the included studies (irrespective of type [i.e., overviews of reviews or guidance documents]) in tables. We present reporting items recommended as additional information to the PRISMA-NMA and/or PRISMA 2020 in tables. The frequency of items suggested in the overall sample of studies is depicted in bar-plots. We summarized the findings from overviews of reviews by providing details on the objectives, inclusion criteria, number of NMAs included in the overview, timeframe of the assessed literature, conflicts of interest, the reporting or methodological guidelines used for appraisal, and a summary of the authors’ conclusions. For guidance documents, we presented a summary of the objectives, conflicts of interest, and authors’ conclusions in tables. RESULTS Literature search The literature search resulted in 2,815 citations identified through databases and registers, and 464 records identified through other methods including grey literature, reference scanning, and steering committee nomination ( Figure 2 ). Prior to screening, 715 duplicates were removed, while 2,344 records were excluded at level one. At level two, we assessed 209 citations, of which 137 were excluded. In total, we included 72 papers: 62 primary studies and 10 companion reports (see Appendix 8 for final list of includes). Seven of the companion reports were extracted using the same process as for the primary studies to support the findings of their main papers. 33 – 39 Of the remaining three companion reports, two were linked to the original PRISMA-NMA paper, 22 , 40 and one was a correction paper. 41 The original PRISMA-NMA paper was included as a unique study; however, its data were not extracted or included in the final frequency counts as it is the study being updated in this review. Overall, 61 unique studies were extracted. Download figure Open in new tab Figure 2. PRISMA Flow Diagram for study selection. Study characteristics The study country of origin of the primary author, based on their affiliation, represented 15 countries ( Table 1 ). The most commonly represented countries within the total 61 studies were: Canada (n = 14; 23.0%), followed by the UK (n=12; 19.7%), China (n=7; 11.6%), Switzerland (n=4; 6.6%), and Brazil (n=4; 6.6%). A breakdown of study types is shown in Table 1 . Journals were the source of 51 (83.7%) studies, while the remaining studies were from grey literature sources including 2 (3.3%) textbooks, 6 (9.8%) reports, one (1.6%) presentation, and one (1.6%) thesis. Funding was reported in 34 (55.7%) of the 61 studies, and public funds were the most frequent source among the 34 studies reporting funding (n=27; 79.4%). Of the 61 included studies, 23 (37.7%) were guidance documents and 38 (62.3%) were overviews of reviews with NMA. Of the 23 guidance documents, 12 (52.2%) addressed reporting in NMA and 11 (47.8%) assessed methodological quality in NMA. Of the 38 overviews of reviews, 28 (73.7%) evaluated reporting completeness or quality in NMA and 10 (26.3%) evaluated quality or risk/source of bias in NMA methods. View this table: View inline View popup Table 1. Characteristics of included studies (n=61) Overview of reviews with NMA The median number of NMAs included in each of the overviews was 62 (interquartile range [IQR: 25 to 200 NMAs]; Appendix 9: Table 2 ). The median timeframe assessed for NMAs in the literature was 51 years (IQR: 12.75 to 54.25 years). The longest timeframe spanned 58 years, from the assumed inception of databases in 1964 (based on MEDLINE 42 ) to June 30, 2022 43 . In contrast, the shortest timeframe covered was 729 days, from January 1, 2018 to December 31, 2019. 44 Conflicts of interest were reported in 31 (81.6%) overviews of reviews, with nine (23.7%) specifically disclosing conflicts of interest. Of the 38 overviews of reviews 16 (42.1%) used PRISMA-NMA, three (7.8%) PRISMA, two (5.2%) PRISMA-IPD 45 [extension to individual participant data], nine (23.7%) A Measurement Tool to Assess Systematic Reviews (AMSTAR) 46 (or AMSTAR 2 or R- AMSTAR), seven (18.4%) the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) 47 and seven (18.4%) national or international guidelines (e.g., CDA, 48 NICE 11 ). For example, Lee et al . 39 revealed low-quality of conduct and reporting of NMAs published before 2017 with the most underreported items being network geometry, inconsistency assessment, and protocol registration. Gao et al . 49 noted that the quality of NMAs published before 2018 was variable, including concerts regarding assessment of publication bias, evaluation of inconsistency, reporting of network geometry, and the structure of presentation. Similarly, Williams et al . 50 highlighted that most NMAs published between 2008 and 2017 rarely assessed inconsistency or provided ranking plots and lacked presentation of effect estimates across all treatment comparisons with treatment rankings. View this table: View inline View popup Table 2. Characteristics of overviews of reviews with NMA (n=38) Guidance documents The 23 guidance documents included in this scoping review aimed to provide tools and frameworks to enhance the reporting (n=12, 52.2%) and methodological quality (n=11, 47.8%) of NMAs (Appendix 10: Table 3). Chiocchia et al . 17 presented the Risk of Bias due to Missing Evidence in Network Meta-Analysis (ROB-MEN) tool, which evaluates the risk of within-study and across-study bias due to missing evidence for each pairwise comparison in a NMA. Similarly, we identified studies presenting different approaches to evaluate credibility of NMA findings. Nikolakopoulou et al . 20 presented the Confidence in Network Meta-Analysis (CINeMA) framework, which evaluates confidence in NMA results, Brignardello-Petersen et al . 21 presented the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach extended to NMA to judge the certainty of NMA estimates, and Phillippo et al . 84 presented the threshold analysis approach to assess confidence in NMA findings relevant to guideline recommendations and proposed methods to quantify the sensitivity of recommendations to plausible changes. Furthermore, the Risk of Bias in Network Meta-Analysis (RoB NMA) tool was introduced by Lunny et al . 85 as a guidance to assess risk of bias in NMA and to identify potential limitations in NMA conduct that could lead to biased results and conclusions. Overall, conflicts of interest were reported in eight (34.8%) guidance documents, with three (13.0%) specifically disclosing conflicts of interest. PRISMA items Across the 61 included studies, we identified 55 reporting items recommended as additional information to PRISMA-NMA or PRISMA 2020 (Appendix 11: Table 4 ). Among these 55 items, 37 were specific additional recommendations for PRISMA-NMA ( Table 4 ). The frequencies of reporting for both the standard and additional guidance items beyond PRISMA-NMA or PRISMA 2020 in the 61 included studies are presented in Figure 3 . The items reported by the fewest included studies were for the Availability of Data, Code, and Other Materials (n=4; 6.6%), Title (n = 14; 23.0%), Abstract (n = 15; 24.6%), and Certainty of evidence in results (n = 15; 24.6%) items, while the recommendations reported by most studies were for Synthesis methods (n = 48; 78.7%), Assessment of inconsistency (n = 45; 73.8%), Results of synthesis (n = 40; 65.6%), and Network geometry (n = 34; 55.7%). Among the 61 unique studies and seven companion reports that were extracted (n=68), additional items not specified in the PRISMA 2020 or the PRISMA-NMA checklists were recommended in 52 (76.5%) studies including defining pre-specified nodes and describing the node-making process, 14 , 16 , 21 indicating whether statistical methods preserving within-study randomization were used, 50 , 58 , 64 , 74 , 86 and in the presence of inconsistency, specifying whether both direct and indirect evidence were included in the NMA. 50 , 58 , 64 , 74 , 86 Other frequent recommendations included describing the statistical model used to combine results, along with the associated algebra and analysis code, 52 , 75 , 77 , 78 detailing analysis methods to assess consistency and/or the transitivity assumption, 49 , 54 and reporting methods for evaluating the overall certainty of evidence (CINeMA, GRADE-NMA, GRADE for pairwise meta-analysis). 17 , 20 , 36 , 44 , 50 , 59 , 63 , 87 No additional reporting guidance was identified for the following PRISMA 2020 items: information sources, data collection process, conclusions, registration and protocol, support (funding), and competing interests. Similarly, no additional reporting guidance was identified for the presentation of network structure within the results category among the five NMA-related items. Download figure Open in new tab Figure 3. Frequencies of recommending each PRISMA item, considering both PRISMA-NMA and PRISMA 2020, in the included studies (n=61). Abbreviations: NMA: Network Meta-Analysis; PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses; SoE: Summary of Evidence; CoI: Competing Interests; RoB: Risk of Bias. View this table: View inline View popup Table 4. Additional items for PRISMA-NMA domains across included studies (n=61) DISCUSSION This scoping review highlights the progress and gaps in the reporting quality of NMAs since the introduction of the PRISMA-NMA extension in 2015. 2 While NMAs have gained prominence in evidence synthesis, their methodological transparency and reporting completeness remain variable. Our findings show that the reporting of synthesis methods, methods to assess consistency and/or transitivity and their results, as well as of network geometry have received the most attention in overview of reviews with NMAs and NMA reporting guidance documents. This likely reflects their critical importance to the reliability of NMA results. However, reporting of essential elements such as the title, abstract, and certainty of evidence were frequently overlooked in reporting which may reduce the accessibility and practical utility of NMA findings. The findings from this review demonstrates a clear need to update PRISMA-NMA to address evolving methodologies and reporting challenges. Although this review primarily focuses on literature addressing reporting, rather than new methodological advancements, we recognize that evolving NMA methods (e.g., component NMA, individual participant NMA) may warrant attention in updated guidance. Recent approaches on evaluating certainty of evidence in NMA findings, such as the CINeMA framework, 20 GRADE-NMA, 21 and threshold analysis, 84 as well as the RoB NMA tool to assess risk of bias in NMA, 17 emphasize the growing complexity of NMAs and the demand for rigorous evaluation of confidence and methodological quality. However, the adoption of these approaches has not been universal, underscoring the need for additional reporting guidance to promote their integration into practice. Importantly, this review identifies areas where PRISMA-NMA 2 can be expanded to enhance its relevance, coverage, and usability. For example, defining pre-specified nodes, 36 , 62 , 85 , 88 specifying statistical methods that preserve within-study randomization, 50 , 58 , 64 , 74 , 86 and describing methods used to explore the consistency and/or transitivity assumptions, 49 , 54 were frequently recommended in our included studies, but are not currently emphasized in PRISMA- NMA. Addressing these gaps in the updated checklist could improve the transparency and reproducibility of NMAs. Another significant finding is that the included articles placed little emphasis on reporting of competing interests (e.g., those related to the interventions assessed in the NMA). This omission could undermine trust in NMA findings. Strengthening the focus on this element in the updated PRISMA-NMA guideline could better align NMA practices with open science and transparency. Additionally, the included studies highlighted the importance of protocol transparency and data sharing, 44 , 92 aligning with the PRISMA 2020 1 and EQUATOR 100 guidance, as well as recent calls for open science promoting for reproducible research. The strengths of our scoping review lie in its systematic approach and extensive engagement with knowledge users. By employing an integrated knowledge translation framework, we incorporated valuable insights throughout the research process, from refining the research question to interpreting the findings. A diverse range of knowledge users, including patient partners, journal editors, healthcare providers, policymakers, methodologists and statisticians, will be actively involved in all steps of updating the PRISMA-NMA guideline. This inclusive approach offers an opportunity to ensure the reporting guideline meets the needs of various end-users of evidence. Our review adhered to the 2020 JBI methodological guidelines for scoping reviews, 24 with reviewers working in pairs and independently for screening and data extraction. We included both published and unpublished studies in any language, and the results were reported following the PRISMA extension for scoping reviews. 25 Some limitations of this scoping review are worth noting. First, despite our systematic efforts to identify all relevant studies, it is possible that some studies were missed. However, our search strategy was developed by an experienced librarian, peer-reviewed by a second librarian, and all citations were screened in duplicate by our team. Also, we leveraged the expertise and experience of our authorship team to identify any further studies for inclusion. Second, we did not conduct a risk of bias assessment for the included studies. This is consistent with guidance for scoping reviews, which typically aim to map the available evidence rather than critically appraise individual sources of evidence. 24 , 25 Our primary objective was to compile a comprehensive list of potential checklist items to inform the update of the PRISMA-NMA reporting guideline, rather than to synthesize findings or evaluate the quality of the included evidence. Third, although we conducted the categorization of items in duplicate and had it reviewed by the steering committee, it is possible that some items could belong to a different category, which may affect the frequency calculations of each PRISMA item. This study provides a basis for a Delphi panel survey and a subsequent online meeting of experts and knowledge users that will be held in 2025. The updated PRISMA-NMA should emphasize the principles of open science, transparency, and inclusivity by addressing existing reporting gaps and integrating perspectives from diverse knowledge users, including patients and the public. This approach can enhance trust, improve reproducibility, and strengthen the impact of NMAs supporting evidence-informed decision-making across healthcare and policy settings. Lastly, this study may be of particular interest to methodologists, as it provides valuable insights into the process of updating a reporting guideline. CONCLUSIONS This scoping review underscores the importance of updating the PRISMA-NMA reporting guideline to address gaps in reporting and align with advancements in NMA methodologies. Notable developments in areas such as synthesis methods, consistency and/or transitivity assessment, and critical aspects like certainty of evidence and transparency around competing interests have been overlooked in reporting. Expanding the PRISMA-NMA guideline to include additional guidance, such as reporting of node-making strategies and methods for assessing certainty of evidence, is essential for improving the usability and reliability of NMAs. Supplementary Files File name: Supplementary Appendix Document.docx File format: .docx Title of Data: Appendices Description of Data: Appendices for manuscript File name: PRISMA-ScR Checklist.docx File format: .docx Title of Data: PRISMA-ScR checklist Description of Data: PRISMA-ScR checklist for manuscript Data Sharing The results and details of the studies included in this review can be found in the supplementary material. Data Availability All datasets supporting the conclusions of this article are included within the article. Dissemination We plan to share findings in the following ways: Manuscript in a peer-reviewed journal Research brief National and international meetings/webinars Executive summary with infographics Websites (e.g., Knowledge Translation Program) Newsletters (e.g., Knowledge Translation Canada, Strategy for Patient-Oriented Research Evidence Alliance) Social media (e.g., BlueSky, LinkedIn) Ethics Approval Not applicable. Patient and public engagement Reporting completeness of a systematic review directly impacts patient care through evidence-based health and public health decision-making. Patients and the public can help promote reporting completeness and improve the use of systematic reviewers with network meta- analysis (NMA) in decision-making. Our team and steering committee involved a patient partner (MS) with expertise in patient engagement in reporting guidelines and systematic reviews with NMA, who provided their comments throughout the process of this scoping review. Our patient partner wrote a lay summary for this review (see Appendix 2). Transparency statement The lead author (AAV) is the manuscript’s guarantor and affirms that it is an honest, accurate, and transparent account of the study being reported. No important aspects of the study have been omitted and any discrepancies from the study as originally planned have been explained. Role of the funding source This study was funded by the Canadian Institutes of Health Research Project Grant (No. 190036). ACT is supported by a Tier 1 Canada Research Chair in Knowledge Synthesis for Knowledge Users. SES is supported by a Tier 1 Canada Research Chair in Knowledge Translation. The funders had no role in the conceptualization, design, data collection, analysis, decision to publish, or preparation of the manuscript. Declaration of Interests All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf . BH has previously received honoraria from Eversana Inc. for the provision of methodologic advice related to the conduct of systematic reviews and network meta-analyses. The remaining authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Open Access License This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-4.0) license which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/ Acknowledgments We thank Dr. Jessie McGowan for developing the literature searches. We thank Douglas M Salzwedel, MLIS (Information Specialist, Therapeutics Initiative, University of British Columbia) for peer reviewing the MEDLINE search strategy. We thank Neal Haddaway and Carole Lunny for providing feedback on our original grant proposal. We thank Yang Guo for translating and extraction the included Chinese-language study. We thank Brahmleen Kaur and Evan Mitton for their support in formatting the paper. We acknowledge the traditional land of the Huron-Wendat, the Seneca, and most recently, the Mississaugas of the Credit River on which our research team operates in Toronto, Ontario, Canada. This land is still home to many Indigenous people from across Turtle Island and we are grateful to have the opportunity to work on this land. Footnotes Funding : Canadian Institutes of Health Research (CIHR) Project Grant (No 190036) E-mail: Areti-Angeliki.Veroniki{at}unityhealth.to , E-mail: andrea.tricco{at}unityhealth.to , E-mail: daniella.rangira{at}unityhealth.to , E-mail: joanne.mckenzie{at}monash.edu , E-mail: tianjing.li{at}cuanschutz.edu , E-mail: sharon.straus{at}utoronto.ca , E-mail: maureen_smith{at}rogers.com E-mail: ferran_catala{at}outlook.com , E-mail: dwolfe{at}ohri.ca , E-mail: vera.nincic{at}unityhealth.to , E-mail: menelaos.konstantinidis{at}mail.utoronto.ca , E-mail: juan.franco{at}med.uni-duesseldorf.de , E-mail: daviditovey{at}gmail.com , E-mail: saisurabi.thirugnanasampanthar{at}unityhealth.to , E-mail: rachel.warren{at}unityhealth.to , E-mail: gawells{at}ottawaheart.ca , E-mail: adrienne.stevens{at}phac-aspc.gc.ca , E-mail: bhutton{at}ohri.ca , E-mail: jasmeen.dourka{at}unityhealth.to References 1. ↵ Page MJ , McKenzie JE , Bossuyt PM , Boutron I , Hoffmann TC , Mulrow CD , et al. 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