In this section: Commonly used abbreviations | Common abbreviations that do not need to be defined | Acronyms used within Cochrane | e.g., etc., and i.e. | Currency abbreviations
Commonly used abbreviations
This table lists some abbreviations commonly used in Cochrane Reviews. See also Common abbreviations that do not need to be defined and Frequently used names.
| Term | Abbreviation |
| absolute risk reduction | ARR |
| control group risk (avoid control event rate) | CGR |
| controlled clinical trial | CCT |
| confidence interval | CI |
| degrees of freedom | df |
inverse variance or intravascular Note: if both terms are abbreviated in a review, use lower case 'iv' for intravascular. | IV |
| Mantel-Haenszel | M-H |
| mean difference (avoid weighted mean difference) | MD |
| number needed to treat for an additional beneficial outcome (avoid number needed to treat) | NNTB |
| number needed to treat for an additional harmful outcome (avoid number needed to harm) | NNTH |
| odds ratio | OR |
| Peto odds ratio | Peto OR |
| randomized controlled trial | RCT |
| risk difference | RD |
| risk ratio (formerly called relative risk in Review Manager 4) | RR |
| standard deviation | SD |
| standard error | SE |
| standardized mean difference | SMD |
Common abbreviations that do not need to be defined
Also note that it is not necessary to define the full unit name of standard SI units (see General guidance on SI units in the section on Units and systems of measurement).
| Abbreviation | Term |
| AIDS | Acquired immune deficiency syndrome |
| CONSORT | Consolidated Standards of Reporting Trials |
| COVID-19 | coronavirus disease 2019 |
| DNA | Deoxyribonucleic acid |
| GRADE | Grading of Recommendations, Assessment, Development and Evaluation |
| HIV | Human immunodeficiency virus |
| MeSH (not MESH or Mesh) | Medical Subject Headings |
| PRISMA | Preferred Reporting Items for Systematic Reviews and Meta-Analyses |
| UK | United Kingdom |
| USA | United States of America |
Acronyms used within Cochrane
A list of acronyms used within Cochrane is available in the Glossary of terms.
e.g., etc., and i.e.
e.g.: an abbreviation for ‘for example’ (from the Latin ‘exempli gratia’) that can be used in lists within the text, when examples are given in brackets, and in tables (for brevity). Use the form ‘e.g.’ with no following comma.
etc.: always write 'etc.' (followed by a full stop) in Cochrane Reviews. Use a comma before ‘etc.’ if it follows more than one item in a list. If 'etc.' is used at the end of a sentence, do not use two full-stops.
i.e.: an abbreviation for ‘that is’ (from the Latin ‘id est’) that can be used for lists within the text, when information is given in brackets, and in tables (for brevity). Use the form ‘i.e.’ with no following comma.
| Correct | Incorrect |
| e.g. (e.g. men, women, children) | e.g., eg, eg |
| i.e. (i.e. men, women, children) | i.e., ie, ie |
| etc. (Canada, USA, Germany, etc.) | etc e.t.c. |
Currency abbreviations
Currencies should be expressed using standard three-letter codes defined by ISO-4217, but as with other abbreviations it is generally helpful to expand on first use.
Common codes include USD (US dollar), EUR (euro), and GBP (pounds sterling). Full list: https://en.wikipedia.org/wiki/ISO_4217#Active_codes