Versions and changes to the Handbook

Process for updating the Handbook

For details on when and how updates to the Handbook are made, please see here.

Handbook updates pending 

      Chapter 10:

      • Updates throughout the chapter reflect the most up-to-date research, tools and best practices regarding the random-effects model.

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      What's new in Handbook version 6.5 (2024)

      Chapter III-S1 Supplementary material

      • Edits throughout to reflect developments in reporting practices. These updates have not resulted in any methods-related changes to the MECIR conduct standards.

      Chapter 4:

      • Updates throughout the searching and selecting studies chapter that reflect the most up-to-date research, tools and best practices.

      Technical supplement to Chapter 4:

      • Updates throughout the searching and selecting studies chapter that reflect the most up-to-date research, tools and best practices.

      Chapter 20-Technical Supplement:

      • This new technical supplement focuses on the integrated full systematic review of economic evidence as a methodological framework. These updates have not resulted in any methods-related changes to the MECIR conduct standards.

      Chapter 13:

      • This update introduces the ROB-ME (“Risk Of Bias due to Missing Evidence”) tool for assessing the risk of bias due to missing evidence in a meta-analysis. These updates have not resulted in any methods-related changes to the MECIR conduct standards.
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      What's new in Handbook version 6.4 (2023)

      Chapter I

      • Edits throughout due to changes to organizational structures in Cochrane and to update other details relevant to Cochrane. Jacqueline Chandler stepped down as author and Ella Flemyng has been added as an author.

      Chapter II

      • Edits throughout due to changes to organizational structures in Cochrane, changes introduced by a new focused review format, and changes to how to propose Cochrane Reviews.
      • Jacqueline Chandler stepped down as author and Ella Flemyng has been added as an author.

      Chapter III

      • Edits throughout due to changes introduced by a new focused review format, including the retirement of the Cochrane's Protocol and Reporting standards (MECIR items PR1 to PR44 and R1 to R109) and the endorsement of PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analysis) reporting guidelines for use in Cochrane Reviews of interventions
      • Jacqueline Chandler has stepped down as author and Ella Flemyng has been added as an author. T

      Chapter IV

      • Edited to reflect the retirement of Cochrane's reporting standards for Updates (MECIR items UR1 to UR7) to ensure this information is included in the chapter.
      • Jacqueline Chandler has stepped down as author and Ella Flemyng has been added as an author.

      Chapter V

      • Edits throughout due to changes to organizational structures in Cochrane and changes introduced by a new focused review format.

      Chapter 2

      • Edits to section 2.4.1 due to changes to organizational structures in Cochrane and section 2.5.2 related to changes introduced with a new focused review format.

      Chapter 3

      • Edits to Table 3.2.c. related to changes introduced with a new focused review format.
      • MECIR items C17 and C18 were added in MECIR Box 3.2.d.

      Chapter 4:

      • Updates throughout the searching and selecting studies chapter that reflect the most up-to-date research, tools and best practice. These updates have not resulted in any methods-related changes to the MECIR conduct standards.
      • Chris Marshall has stepped down as author.

      Technical supplement to Chapter 4:

      • Amended sentence in section 3.4 (page 53) to correct search syntax; previous sentence was "For example, in CENTRAL and Ovid it is possible to combine sets using the syntax HarmoniSR Working Group -#10  and ‘or/1-100’ respectively." and has been updated to "For example, in CENTRAL and Ovid it is possible to combine sets using the syntax {OR #1-#100} and ‘or/1-100’ respectively."

      • Chris Marshall has stepped down as author.

      Chapter 6:

      • Supplementary material 10.S1 (version 6.3, 2022), titled Statistical Algorithms in Review Manager 5.1, has been relocated into the RMW Knowledge Base. The last paragraph of section 6.1.1 has been updated to reflect this.
      • MECIR item C61 was included in a new box called MECIR Box 6.4.a, with additional context in the main text.

      Chapter 10:

      • The Supplementary material associated with Chapter 10 (Version 6.3, 2022) will be relocated into the RMW Knowledge Base. The last paragraph of section 10.2 needs to be updated to reflect this change.
      • MECIR item C62 was included in a new box called MECIR Box 10.10.a., with additional context in the main text.

      Chapter 14

      • Edits to section 14.1.1 to confirm all Summary of Findings tables in Cochrane Reviews appear at the beginning, before the Background section.
      Chapter 15:
      • Amended typos in Table 15.5.c, reproduced from Guyatt et al. 2013b (Erratum published here). For SMD of 0.9, when the event is undesirable, the risk difference is -0.04 (-4%) instead of 40%. For SMD of 0.2, when the event is desirable, the risk difference is 0.06 (6%) instead of 61%.
      • Amended the text for MECIR item C72 in MECIR Box 15.3.a.

      Chapter 20:

      • Amended EMBASE (OvidSP) filter reported in Box 20.2.e to fix curly inverted commas (straight are required) and other related errors in lines 3, 4 and 6.

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      What's new in Handbook version 6.3 (2022)

      Chapter III:

      • Changes to the reporting chapter reflect developments in reporting practices in line with PRISMA 2020, new guidance for writing a Cochrane plain language summary and additional reporting requirements when assessing risk of bias using updated tools such as RoB 2 and ROBINS-I. These updates have not resulted in any changes to either MECIR reporting standards or methods-related changes to the MECIR conduct standards.

      Chapter 4 and technical supplement to Chapter 4:

      • Updates throughout the searching and selecting studies chapter that reflect the most up-to-date research, tools and best practice. These updates have not resulted in any methods-related changes to the MECIR conduct standards (some standards were tweaked to help with readability). 

      Chapter 7:

      • Clarifying that the original risk of bias tool can still be used in Cochrane Intervention Reviews, though Risk of Bias 2 is preferred if author and editorial teams are able to use it. MECIR conduct standards were updated to clarify this.

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      What's new in Handbook version 6.2 (2021)

      Version 6.2 available here.

      Chapter 1

      • Section 1.3, ‘Declarations of interest’ subsection updated to reflect Cochrane’s new conflict of interest policy.

      Chapter 3

      • Section III.3.7, ‘Declarations of interest’ subsection updated to reflect Cochrane’s new conflict of interest policy.

      Chapter 4

      • Section 4.4.6 updated to clarify definitions for errata and retractions; two references added to the chapter; and small edits for formatting or readability edits that do not affect scientific content.
      • Supplementary 1: Section 3.6.3 clarification that the search is optimised for CINAHL Plus; Section 3.7 updates to Box 3.g. search strategy for CENTRAL; Section 3.9 updates on searching for retractions; and small edits for formatting or readability edits that do not affect scientific content.

      Chapter 7

      • Section 7.3.2, MECIR Box 7.3.c, C56: Highly desirable -changed to- C56: Mandatory

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      What's new in Handbook version 6.1 (2020)

      Only chapter 14 and 20 are reprinted as version 6.1, all other chapters remain as 6 versions.

      Version 6.1 is available here. 

      Chapter 14

      • 14.2.2 Domains that can lead to decreasing the certainty level of a body of evidence: In each case, if a reason is found for downgrading the evidence, it should be classified as ‘no limitation’ (not important enough to warrant downgrading), ‘serious’ (downgrading the certainty rating by one level) or ‘very serious’ (downgrading the certainty grade by two levels). For non-randomized studies assessed with ROBINS-I, rating down by three levels should be classified as ‘extremely’ serious.

        - changed to -

        In each case, if no reason is found for downgrading the evidence, it should be classified as ‘no limitation or not serious’ (not important enough to warrant downgrading). If a reason is found for downgrading the evidence, it should be classified as ‘serious’ (downgrading the certainty rating by one level) or ‘very serious’ (downgrading the certainty grade by two levels). For non-randomized studies assessed with ROBINS-I, rating down by three levels should be classified as ‘extremely’ serious.

      Chapter 20

      • Patricia Aluko is now the first and corresponding author for Chapter 20 on economic evidence, and Ian Shemilt has stepped down as co-author. This change is reflected in the new authorship list and citation of the Chapter.

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      What's new in Handbook version 6 (2019)

      Version 6 was a major revision of the Handbook, and virtually all of it was updated, revised or rewritten from Version 5. A PDF summary of the new material is available.

      Version 6 is available (from Oct 1st, 2019) here.

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      What's new in Handbook version 5.2.0 (June 2017)

      Only chapters 1, 8, 9, 10, 11,12 and 21 are reprinted as version 5.2.0, all other chapters remain as 5.1.0 versions.

      Version 5.2 is available here.

      Where we refer to individual MECIR standards in the text, a symbol in the margin highlights the standard covered. Summary tables of all chapter relevant MECIR standards are at the end of each chapter. We have clarified terminology throughout these chapters where we refer to included ‘studies’ rather than ‘trials’.

      Chapter 1

      • Various amendments for consistency with the comparable chapters in the Cochrane Handbook for Reviews of Diagnostic Test Accuracy.
      • New Section 1.3 outlining the four kinds of Cochrane Reviews (intervention, diagnostic test accuracy, overviews and methodology).
      • Old Section 1.4, ‘Contributors to the Handbook’ relocated to the Preface.
      • Updated information on the Cochrane Library, including which databases are archived and no longer actively updated (Section 1.4).
      • New Section 2.5 brings together updating information on Cochrane training, software and guidance on resources and funding. Information internal to Cochrane (such as the internal workings of Archie) has been removed.

      Chapter 8

      • Includes a description of the feature in RevMan 5.3 allowing ‘Risk of bias’ assessments to be presented visually on forest plots (Section 8.6).
      • Addition of recent empirical evidence (including from the BRANDO study) of the impact of random sequence generation on effect estimates (Section 8.9.1), allocation concealment (Section 8.10.1), blinding of participants and personnel (Section 8.11.1), blinding of outcome assessors (Section 8.12.1) and selective outcome reporting (Section 8.14.1).
      • Additional text added to emphasize the importance of assessing incomplete outcome data separately for different outcomes or time points (Section 8.13.2).
      • New Section 8.16.1.6 on issues that have been raised in relation to risk of bias, but for which the Handbook is unable to provide definitive guidance at present, including the influence of funders, early stopping, and single-centre versus multi-centre studies.

      Chapter 9

      • New Section 9.1.2.1 on the importance of checking data before completing a synthesis, including checking the magnitude and direction of effect in the synthesis against the original study data. This can avoid several possible problems, including errors in the published data, data collection, any calculations or manipulation of data, and data entry into RevMan.
      • Additional emphasis on the importance of considering missing participant data and its impact on meta-analysis (Section 9.4.2).
      • Additional emphasis on the uncertainty of estimating the I2 statistic to quantify heterogeneity when the number of studies in a meta-analysis is small (Section 9.5.2).
      • Clarification that it is It is a mistake to compare within-subgroup inferences such as P values to test for a significant difference between subgroups, and that a formal statistical test to compare subgroups should be used (Section 9.6.3.1).
      • Change in terminology from ‘baseline risk’ to the preferred ‘underlying risk’ when discussing possible sources of heterogeneity (Section 9.6.7).

      Chapter 10

      • Provides updated evidence on the prevalence of reporting bias from studies of FDA data (Section 10.2.1), the peer review process (Section 10.2.1.2), industry documents made available after legal challenges (Section 10.2.1.3), and the publication of positive trials in prestigious journals (Section 10.2.2.2).
      • Includes a recommendation to search systematically for unpublished trial data, including a brief discussion of sources (Section 10.3.2).
      • Notes that the Clinicaltrials.gov trials register now requires preliminary results to be posted within one year of the study’s completion (Section 10.3.3).
      • Notes that the minimum number of trials required to generate a funnel plot with adequate power to detect asymmetry may be considerably higher than 10 in some circumstances. (Section 10.4.3.1).
      • New Section 10.4.4.7 discusses regression methods for dealing with potential reporting biases.

      Chapter 11

      • Title changed from ‘Presenting results and ‘Summary of ‘Findings’ Tables’ to ‘Completing ‘Summary of findings’ tables and grading the confidence in or quality of the evidence’.
      • Old introduction removed (Section 11.1)
      • Old Section 11.2 ‘Reporting the results of the search’, including PRISMA flow diagrams and the ‘Characteristics of included studies’ table, has been removed. This content will be incorporated into updated chapters on searching and reporting the review in Version 6 of the Handbook.
      • Old Section 11.3 ‘Data and analyses’, including the ‘Data ans analyses’ section of a review, forest plots and other data tables has been removed. This content will be incorporated into anew chapters on meta-analysis and reporting the review in Version 6 of the Handbook.
      • Specifically lists the footnotes as an essential component of a SoF table (Section 11.1.3)
      • Updated to refer to the new SoF software, GRADEpro GDT  (Section 11.1.4)
      • Table 11.2.e ‘Judgements about indirectness by outcome’ added, based on GRADEpro GDT, to assist authors in assessing the indirectness of the evidence in their review in relation to the question originally asked.
      • Further guidance included about the use of the Optimal Information Size (OIS) in assessing the imprecision of a body of evidence (Section 11.2.2).
      • New section 11.2 ‘Assessing the quality of a body of evidence’, including guidance on GRADE, moved here from Chapter 12.
      • New Section 11.3 Describing the assessment of the quality of a body of evidence using the GRADE framework, providing guidance on how to express justifications for downgrading or upgrading the quality of the body of evidence using the GRADE approach.

      Chapter 12

      • Greater clarity on terminology used e.g. generalisability and numbers needed to treat.
      • Old section 12.2 ‘Assessing the quality of a body of evidence’, including guidance on GRADE, moved to Chapter 11.
      • Extended Section 12.6 on implications for research with an additional table 12.6a providing a structured approach to the interpretation of the quality of a body of evidence according to individual GRADE criteria.

      Chapter 21

      Please note this chapter will be replaced by and integrated into at least two new chapters in Version 6: Issues of Equity and Specific populations, and Complex Interventions.

      • Greater clarity defining public health and health promotion interventions emphasizing population level rather than individual level intervention are of interest that operate within a broader context.
      • Database table at 21.3 is updated
      • Section 21.4 on assessment of study quality and risk of bias is updated.
      • At section 21.7 additional frameworks are added to assist in determining sustainability

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      What's new in Handbook version 5.1.0 (March 2011)

      A PDF summary of these changes is also available.

      Version 5.1 is available here.

      Chapter 1

      • Section 1.1.3: The publication frequency of the CDSR has been updated (from quarterly to monthly).

      Chapter 2    

      • Section 2.3.6: Reference to the training web site and open learning modules has been updated.

      Chapter 3

      • Box 3.2.c and Section 3.2.5.4: Criterion 5 (Accumulation of changes) for creating a new citation version has been relaxed slightly.

      Chapter 4

      • Section 4.5 (Methods): A new section about planning a ‘Summary of findings’ table has been added.
      • Section 4.5 (Results): A reference PRISMA flow diagrams has been inserted under ‘Results of the search’.
      • Section 4.5 (Discussion): The section on ‘Quality of the evidence’ has been amended to refer to ‘Summary of findings’ tables and GRADE assessments.
      • Section 4.7.2: Guidance on referring to ‘Other published versions of this review’ has been clarified. As a general rule, only new citation versions of publications in the CDSR should be listed (i.e. those that yield a new MEDLINE record).
      • Table 4.9.a and Section 4.9.1: Two new types of RevMan Figure have been added: RevMan study flow diagram (PRISMA template) and RevMan flow diagram.

      Chapter 5

      • Section 5.4.1: Guidance about using outcomes as criteria for including studies has been clarified, including advice against using  a lack of ‘usable’ data as a criterion.

      Chapter 6

      • Section 6.6.1: Advice to document the search results has been added in anticipation of a PRISMA flow diagram.
      • Section 6.6.2: Clarity has been added that the search methods should be presented in a protocol, even if the detailed (line by line) search strategy is not.

      Chapter 8

      • The Cochrane ‘Risk of bias tool’ has been modified for RevMan 5.1. The chapter has been modified in numerous places to reflect the modified tool. The changes are summarized in Table 8.5.b. The main alterations are in sections 8.4, 8.5, 8.6, 8.8.3, 8.11, 8.12 [new] and 8.15.
      • The chapter’s editors are now Higgins JPT, Altman DG and Sterne JAC.

      Chapter 9

      • Section 9.6.3.1: A more general version of the test for differences between subgroups is now described, as it has been implemented in RevMan.

      Chapter 10

      • Figure 10.4.c: The figure has been corrected.

      Chapter 11

      • Section 11.2: A new section about PRISMA study flow diagrams has been introduced.
      • Section 11.5.3: The text of bullet point 5 has been modified slightly to clarify the purpose of GRADE.
      • Section 11.5.4: A comment has been inserted to point out the context-specific help file in GRADEpro.

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      What's new in Handbook version 5.0.2 (September 2009)

      Version 5.0.2 is available here.

      Chapter 6

      • Boxes 6.4.a, 6.4.b, 6.4.c, 6.4.d : last lines of each strategy corrected.

      Chapter 13

      • Table 13.2.b: Entries for ITS and ChBA have been corrected for the first two rows.

      Chapter 16

      • Reference added for Hollis 1999 (was missing from browseable version only).

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      What's new in Handbook version 5.0.1 (September 2008)

      Throughout

      • Extensive copy editing for style, spelling and grammar.

      Chapter 3

      • Section 3.2.5.1: Clarification that updated reviews are flagged with a ‘New search’ flag in CDSR.
      • Section 3.5.2: Clarification that withdrawn reviews should be given an ‘Amended’ event in the ‘What’s new’ table.

      Chapter 4

      • Section 4.5: Added “Review authors who wish to mix recommended with optional subheadings should ensure that they are all displayed in appropriately consistent styles, which may require deactivating all of the recommended headings embedded in RevMan and creating them manually.”

      Chapter 6

      • Section 6.2.3.4: Added mention of Section 801 of the Food and Drug Administration Amendments Act of 2007.
      • Section 6.3.2.1: Search strategy in 2nd paragraph rephrased
      • Section 6.4.11: Added mention of search filter appraisal tool.
      • Boxes 6.4.a, 6.4.b, 6.4.c, 6.4.d : Last two lines of each strategy corrected.
      • Box 6.4.f: Lines 9 and 10 of search strategy corrected.

      Chapter 7

      • Section 7.7.6: Added reference to Tierney 2007.

      Chapter 9

      • Section 9.4.1: Added mention of supplementary document Statistical Algorithms in Review Manager 5.
      • Section 9.5.4: Added reference for predictive intervals for random-effects meta-analysis.

      Chapter 11

      • Section 11.5.6.2: Added “If there is an excessive number of outcomes in the review, authors will need to omit the less important outcomes.”
      • Section 11.8: Clarified that trade names should not be used.

      Chapter 12

      • Added new key point, “Quality ratings are made separately for each outcome”.
      • Section 12.6.4: New discussion of source of standard deviations for interpreting SMDs.

      Chapter 13

      • Section 13.1.2, item (e): Removed text “However, justifying a systematic review of NRS on the ground of supplementing randomized trial evidence may be acceptable if the available evidence from randomized trials is of such limited quantity or poor quality that NRS may actually provide better evidence.”
      • Tables 13.2.a and 13.2.b: Added ‘Some other process (specify)? as an option for allocation to groups.

      Chapter 15

      • Section 15.6.1: more information on Purchasing Power Parities and use of gross domestic product deflators.

      Chapter 18

      • Added new key point, “There may be circumstances where the benefits of obtaining IPD are marginal; others where it could be vital.”

      Chapter 21

      • Changed from “health promotion and public health” to “public health and health promotion”.

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      What's new in Handbook version 5 (February 2008)

      Version 5.0 is available here.

      Version 5 was a major revision of the Handbook, and virtually all of it was updated, revised or rewritten from Version 4. A PDF summary of the new material is available.

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