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22.3.2  Abstract

The content under each heading in the abstract should be as follows:

Background: This should be one or two sentences to explain the context or elaborate on the purpose and rationale of the Overview.

Objectives: This should be a precise statement of the primary objective of the Overview, ideally in a single sentence. Where possible the style should be of the form ‘To summarize Cochrane reviews that assess the effects of [interventions or comparisons] for [health problem] for/in [types of people, disease or problem and setting if specified]’.

Methods: This section should succinctly address the search strategy used to identify systematic reviews for inclusion in the Overview and the methods used for data collection and analysis. The latter should be restricted to description of the guidelines used for extracting data and assessing data quality and validity and not include details of what data were extracted. The method by which the guidelines were applied should be stated (for example, independent extraction by multiple review authors).

Main results: This section should begin with the total number of systematic reviews included in the Overview, and brief details pertinent to the interpretation of the results (for example, the quality of the included systematic reviews or a comment on the comparability of the reviews, if appropriate). It should address the primary objective and be restricted to the main qualitative and quantitative results (generally including not more than seven key results). The outcomes included should be selected based on their expected value in helping someone to make a decision about whether or not to use a particular intervention. If relevant, the number of studies and participants contributing to the separate outcomes should be noted, along with the quality of evidence specific to these outcomes. The results should be expressed in narrative as well as quantitatively if the numerical results are not clear or intuitive (such as those from standardized mean differences analyses). The summary statistics in the abstract should be the same as those highlighted in the text of the Overview, and should be presented in a standard way, such as ‘risk ratio 2.31 (95% confidence interval 1.13 to 3.45)’. Both absolute and relative effects should be reported, if possible. However, review authors should be cautious about reporting absolute effects when control group risk for an outcome varies across studies or reviews (see Chapter 11, Section 11.5.5). If overall results are not calculated in an included review, a qualitative assessment or a description of the range and pattern of the results can be given. However, ‘vote counts’ in which the numbers of ‘positive’ and ‘negative’ studies (or reviews) are reported should be avoided.

Authors’ conclusions: The primary purpose of the Overview should be to present information, rather than to offer advice. The Authors’ conclusions should be succinct and drawn directly from the findings of the Overview so that they directly reflect the main results. Authors should be careful not to confuse a lack of evidence with a lack of effect. Assumptions should not be made about practice circumstances, values, preferences, tradeoffs; and the giving of advice or recommendations should generally be avoided. Any important limitations of data and analyses should be noted. Important conclusions about specific implications for research, including systematic reviews, should be included if relevant. Authors should not make general statements that ‘more research is needed’.