Table 1 Some common crucial points that readers should check to see if the systematic review is credible

Purpose of review

Clear research questions

Are they possible to answer and not too vague?

Finding the literature

A clear description of the search criteria

The screening processes

Were the search criteria so clearly explained that the same articles can be found by somebody else?

Was the search assisted by an expert librarian?

Did at least two people search and screen, blind to each other’s findings using clear inclusion/exclusion criteria?

Obtaining information from articles

Extraction of three types of information:

I. descriptive,

II. risk of bias/level of quality,

III. results

The tool to extract risk of bias/quality information

Was the extraction of data done by more than one person, and blindly, and is information transparently reported in tables?

Analysis/synthesis of data

An explanation of how the data would be analyzed (in the Methods section)

Was the analysis so clearly explained that somebody else would be able to get the same results, using the data presented in the tables?

Was it shown how information on RoB/quality was used in terms of what was acceptable and how the level of acceptability influenced the analysis of data or the interpretation of the results?

Results

A full report of the result, no more no less.

Are the research questions answered and if this was not possible, was it explained why not?

“Summary of findings and conclusions” in the Discussion and Conclusions in the Abstract

The Summary of Findings (at the beginning of the Discussion) and the Conclusions (at the end of the Discussion or in the Abstract) all agree and they report also ‘uncomfortable’ results.

Are there any signs of positive or negative ‘spin’ in the Conclusion of the main text or in the Abstract?

Do you trust these authors? If so, now read the Results.

If not, ignore the results, even if they correspond to what you prefer to see!