BackgroundInterventional clinical studies conducted in the regulated drug research environment are reported using International Council for Harmonisation (ICH) regulatory guidance documents: ICH E3 on the structure and content of clinical study reports (CSRs) published in 1995 and ICH E3 supplementary Questions & Answers (Q & A) published in 2012.Since the ICH guidance documents were published, there has been heightened awareness of the importance of disclosure of clinical study results. The use of the CSR as a key source document to fulfil emerging obligations has resulted in a re-examination of how ICH guidelines are applied in CSR preparation. The dynamic regulatory and modern drug development environments create emerging reporting challenges.MethodsRegulatory medical writing and statistical professionals developed Clarity and Openness in Reporting: E3-based (CORE) Reference over a 2-year period. Stakeholders contributing expertise included a global industry association, regulatory agency, patient advocate, academic and Principal Investigator representatives.ResultsCORE Reference should help authors navigate relevant guidelines as they create CSR content relevant for today’s studies. It offers practical suggestions for developing CSRs that will require minimum redaction and modification prior to public disclosure.CORE Reference comprises a Preface, followed by the actual resource. The Preface clarifies intended use and underlying principles that inform resource utility. The Preface lists references contributing to development of the resource, which broadly fall into ‘regulatory’ and ‘public disclosure’ categories. The resource includes ICH E3 guidance text, ICH E3 Q & A 2012-derived guidance text and CORE Reference text, distinguished from one another through the use of shading. Rationale comments are used throughout for clarification purposes.A separate mapping tool comparing ICH E3 sectional structure and CORE Reference sectional structure is also provided.Together, CORE Reference and the mapping tool constitute the user manual.ConclusionsThis publication is intended to enhance the use, understanding and dissemination of CORE Reference.The CORE Reference user manual and the associated website (http://www.core-reference.org) should improve the reporting of interventional clinical studies.Periodic updates of CORE Reference are planned to maintain its relevance.RegistrationCORE Reference was registered with http://www.equator-network.org on 23 March 2015.

Background CORE ( C larity and O penness in R eporting: E 3-based) Reference (released May 2016 by the European Medical Writers Association [EMWA] and the American Medical Writers Association [AMWA]) is a complete and authoritative open-access user’s guide to support the authoring of clinical study reports (CSRs) for current industry-standard-design interventional studies. CORE Reference is a content guidance resource and is not a CSR Template. TransCelerate Biopharma Inc., an alliance of biopharmaceutical companies, released a CSR Template in November 2018 and recognised CORE Reference as one of two principal sources used in its development. Methods The regulatory medical writing and statistical professionals who developed CORE Reference conducted a critical review of the TransCelerate CSR Template. We summarise our major findings and recommendations in this communication. We also re-examined and edited the Version 1 CORE Reference Terminology Table that we first published in 2016, and we present this as Version 2 in this communication. Results Our major critical review findings indicate that opportunities remain to refine the CSR Template structure and instructional text, enhance content clarity, add web links to referenced guidance documents, improve transparency to support the broad readership of CSRs, and develop supporting resources. The CORE Reference ‘Terminology Table’ Version 2 includes estimand as a defined term and an adaptation of the original ‘worked study example’ to incorporate the recently evolved concept of ‘estimands’. Conclusions As TransCelerate’s CSR Template represents an important milestone in authoring CSRs, we offer CSR authors advice and recommendations on its use, similarities, and differences with CORE Reference and advise them to consider shared interpretations between the two. Registration CORE Reference is registered with the EQUATOR Network. The TransCelerate CSR Template is not registered with any external organisation to the knowledge of the authors of this paper. Electronic supplementary material The online version of this article (10.1186/s41073-019-0075-5) contains supplementary material, which is available to authorized users.