Cochrane Style Essentials

Essential style guidelines for authors of Cochrane reviews and protocols
Essential style guidelines for authors of Cochrane reviews and protocols

From the Cochrane Style Manual. Last updated: June 2024. See How to cite.

Cochrane protocols, reviews, and updates must follow the guidance in the Cochrane Style Manual. Key points are summarised here for authors. Our author guidelines provide further guidance on preparing manuscripts for submission to Cochrane.

 

Why does style matter?

We developed Cochrane house style to ensure clarity for our readers and accuracy in our evidence.

Our editors check submissions against this style guide. Follow these essential guidelines to reduce the number of corrections you will need to make when revising your submission.

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Clarity and accuracy

Consistency

Refer to key terms and results consistently throughout all sections:

  • Describe interventions and outcomes in the same terms and using the same names throughout (check all sections where mentioned)
  • Choose your terminology and avoid synonyms for key terms (e.g. use 'study' or 'trial')
  • Your results must be the same wherever they are cited
    • Abstract (Main results, Conclusions) - read a published best practice example.
    • Plain language summary (Key messages, What did we find? Main results)
    • Authors’ conclusions 
    • Summary of findings
    • Results (Effects of interventions)
    • Discussion (Summary of results)
  • Text and numbers in the Results of the search section must match those in the PRISMA flow diagram, and the numbers should add up

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Plain language summary

Your plain language summary shares the findings of your review with non-expert readers of the Cochrane Library:

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GRADE

You do not need to define the term ‘GRADE’ when describing your evidence: 

  • Use ‘quality’ or ‘certainty’ consistently, and cite the GRADE publication that uses the same phraseology
  • Use normal text (not italic) to present GRADE judgements (e.g. very low-quality evidence or very low-certainty evidence)

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Tense and voice

  • Use the active voice to be clear and concise: (e.g. 'two authors extracted data' rather than 'data were extracted by two authors);
  • Explain things you plan to do, using the future tense (e.g. in a protocol for a Cochrane review - 'we will conduct subgroup analyses');
  • Explain things you have done, using the past tense (e.g. in a Cochrane review - 'we conducted subgroup analyses'). 

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Presenting data

  • There are different ways to present summary statistics in the text (see Statistical presentation): 
    • the risk ratio (RR) was 0.14 (95% confidence interval (CI) 0.08 to 0.24); [use this option if the RR and CI have not been abbreviated earlier in the text] 
    • mean difference 1.09 hours (95% CI 0.98 to 1.20); 
    • (RR 1.02, 95% CI 0.87 to 1.19).
  • Where multiple pieces of information are presented within a bracket, use this order and format: (summary statistic, CI; P value, I2; number of trials, number of participants; certainty of evidence; link to analysis).
  • Present numerical results to two decimal places (e.g. RR 0.14) unless the number is very small, in which case use three significant figures. 

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    Formatting

    References and citations

    Include a reference to the Cochrane Handbook, using the reference fields in RevMan.

    Reference type Other
    Authors Higgins JP, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA, editor(s)
    English title Cochrane Handbook for Systematic Reviews of Interventions Version 6.3 (updated February 2022). Cochrane, 2022
    Journal/book/source Available from training.cochrane.org/handbook

    References. See References. 

    • Study/reference identifier: use the last name of the first author and the year of publication as the study/reference identifier (e.g. Baldini 2004). Alternatively, if a trial is more widely known by an acronym, use the format 'TRIALNAME YYYY'; use the year of publication of the primary reference for the trial
    • Authors: list only the first six authors of any reference, separate each author with a comma, and use ‘, et al’ after the sixth author if there are more than six authors; for example, Abera G, Takahashi N, Thugwane J, Roba F, Hwang Y-C, Yegorova V, et al. You must use a comma before ‘et al’
    • Punctuation: no full stops at the end of each line, for example, after the authors or article title
    • Journal article title: the first letter of the first word of the article title should be in upper case; all other words should be lower-case unless they are proper names (trade names, country names, acronyms, etc.) or require an upper-case letter
    • Translated article title: include the English translation of a journal article title if it is provided by the journal or database. If an English translation is not available, only enter the original title
    • Journal title: enter the full journal title using title case (i.e. each substantive word starts with an upper-case letter)
    • Translated journal title: include the English translation of a journal title if it is provided by the journal or database. Place the English title in square brackets after the original journal title
    • Page number style: 324-6 or 256-60 are correct (not 324-326 or 324-26, nor 256-260 or 256-0)

    Citations.

    • Cochrane's focused review format uses a numbered citation system. RevMan will automatically insert your citations as numbers, and will automatically renumber the citations before submission. See the RevMan Knowledge Base.
    • You can use study/reference identifiers as part of a sentence (e.g. 'We included Jones 2001 in the analysis.')
    • You can list study/reference identifiers in brackets, before the full stop at the end of the sentence or within the closest punctuation. See Citing references.
    • If two or more references are used to support one statement, separate each citation with a semicolon. If you are not using numbered citations, RevMan will automatically order your citations alphabetically. See the RevMan Knowledge Base. 
    • Sentences that include multiple pieces of information that are supported by a number of citations should be structured so that it is clear to which piece of information each citation relates, for example 'One trial included children only (Smith 2014), while another included adults only (Jones 2018).'

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    Headings

    Use the RevMan toolbar to format and nest headings at the appropriate level, i.e. a subheading following a level 3 heading should be formatted as level 4, and so on (see Headings). 

    • Subheadings should always be formatted as the heading level below the heading they follow. 
    • Check that level 5 headings are formatted as such and are not normal text presented in bold. 
    • Remove unnecessary capitals from headings; Cochrane uses sentence case (see Use of capitals). 

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    Numbers and dates

    • Numbers: spell out numbers less than 10 in full, unless used with units (e.g. 5 mL) or in a list with other numbers (e.g. 6, 12, and 24 months), or in tables (see Numbers);
    • In the main text, write numbers in full if they appear at the start of a sentence (e.g. 'Two authors extracted data').
    • Dates: spell months out in full to avoid confusion between different regional date formats (e.g. 10 March 2023), and express decades as, for example, 1960s (no apostrophe). 

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    Lists 

    • Choose either bullets or numbered points for all lists throughout the review. Use the bullet/number icons in Review Manager to format lists. 

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    Abbreviations and symbols

    Use abbreviations and acronyms only if they are widely known and not using them could make reading tedious. 

    • Write out in full in the first instance and follow immediately by the abbreviated version or acronym in brackets; for example, 'We contacted the World Health Organization (WHO). The WHO provided the relevant information.' (See When to use abbreviations.) 
    • Use 'e.g.' and 'i.e.' (with full stops, but not followed by a comma), and 'etc.' (see e.g./i.e.).
    • Standard unit abbreviations do not need to be defined (e.g. mL and mg) (see Units).  
    • Insert one space between a number and the unit (e.g. 0.4 mg) (see Units). 
    • Use symbols (e.g. + − & < > =) in text only if the descriptive version is cumbersome or inappropriate. 
    • Keep one space either side of the symbol (e.g. > 100 participants) except for a negative number (e.g. negative pressure of −50 mmHg). 
    • There should be no space either side of / (e.g. 10/51) (see Symbols). 

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    Language and spelling

    • Spelling: be consistent with UK/US English spelling preferences and when using words where different spelling is possible (e.g. randomised and randomized)
    • Pharmaceutical drugs: use the recommended International Non-proprietary Name (rINN) for all pharmaceutical drugs (and put the specific brand name in brackets if needed)
    • Databases: MEDLINE (not Medline); Embase (not EMBASE); OLDMEDLINE (not Oldmedline); PsycLIT (not Psychlit); PsycINFO (not Psychinfo); CINAHL (not CINHAL or Cinahl)
    • Follow Cochrane style for commonly-used terms (see table below)

    handsearching (not hand searching) 

    website (not web site) 

    P value (not p-value) 

    fixed-effect model (not fixed effect model) 

    random-effects model (not random effects model) 

    subgroup (not sub-group) 

    prespecified (not pre-specified) 

    Cochrane (instead of the Cochrane Collaboration) 

    the Cochrane Library (no italics) 

    the Cochrane Central Register of Controlled Trials (CENTRAL) 

    follow up (verb) and follow-up (noun or adjective) 

     

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    Data and analyses

    Presentation of outcomes 

    • Start each individual outcome with a capital letter, including subcategories
    • Write outcomes in sentence case, for example ‘Intranasal spray’, not ‘Intranasal Spray’ 

    Presentation of axes 

    • Relabel axes; the default labelling, ‘Favours [experimental], ‘Favours [control]’ is not acceptable. Use the name of the intervention and control
    • Use sentence case for axes labels and remove square brackets, for example, ‘Favours intranasal spray’ not ‘Favours [Intranasal Spray]’ 

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    Characteristics of included studies

    • Include only brief, concise details; rephrase information from studies to avoid quotations (this is in compliance with Cochrane’s plagiarism policy). If quotations are essential present them within double inverted commas: "Atomoxetine in six sizes from 2.5 to 40 mg were supplied by the manufacturer (Eli Lilly)."
    • If needed, support risk of bias judgements in risk of bias tables with quotations from the study, presented within double inverted commas, "Within each site, participants were randomised in blocks for age groups (2 to < 4 years, and 4 to < 6 years) to treatment groups of 2.5 mg, 5 mg, or placebo."
    • Include the same information for each study, structured under the recommended headings: Methods, Participants, Interventions, Outcomes, Notes
    • Start all boxes with a capital letter
    • Use either bullet points or numbered points, but not both; the choice should match what is used in the review text
    • Follow colons with a lower-case letter, except for proper nouns and acronyms
    • Construct a list of definitions of abbreviations used in tables in the Footnotes section

    Structure your Characteristics of studies as shown below in RevMan, to produce results like this best practice example on the Cochrane Library:

     

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    How to cite

    Mitchell D, Royle E. Cochrane Style Essentials. June 2024. https://training.cochrane.org/online-learning/author-guidelines/essential-style-guidelines.

    Note: change the date shown above to the date of the version you used.

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