This module will discuss the stage in a review when, having found studies relevant to the question, we assess the quality of studies.

Learning objectives

• Understand what is meant by the 'quality' of a trial
• Be aware of empirical studies investigating the relative importance of different aspects of quality
• Be aware of problems in using quality scales to measure quality
• Be aware of ways to reduce bias in quality assessment
• Be aware of methods of incorporating quality in a meta-analysis, for instance use of a threshold or requirement of minimal characteristics, quality related sensitivity analyses, and weighting

Relevant section of the Cochrane Handbook for Systematic Reviews of Interventions

• Chapter 8: Assessing risk of bias in included studies

Where does this go in a Cochrane review?

• The Methods section of your protocol should describe how you plan to do this, and then you should describe how you did this in your complete review
• The section ‘Risk of bias in included studies’ should summarise the quality of all studies, but not describe the quality of individual studies in great detail, although any important flaws in individual studies should be noted here
• The ‘Characteristics of included studies’ table should include details of the methodological quality of individual studies.