SOM Library: Systematic Reviews: Quality Assessment

Quality Assessment

Once screening (article selection) is completed, the Quality Assessment part of the systematic review process may begin.

Since systematic reviews rely on data from other studies, the evidence in a systematic review is only as good as, or as free from bias as, the included studies. Therefore, the methodological quality of each individual study included in a systematic review should be assessed. This process involves appraising, judging, and documenting potential risks of bias.

The quality assessment tool is based upon the types of studies which will be included in your systematic review.

The Cochrane Risk of Bias tool assesses risk of bias in Randomized Controlled Trials (RCTs).
Reviewers assess each study based on five domains:

Risk of bias arising from the randomization process
Risk of bias due to deviations from the intended interventions (effect of assignment to intervention)
Risk of bias due to missing outcome data
Risk of bias in measurement of the outcome
Risk of bias in selection of the reported result

Judgment can be low or high risk of bias, or can express some concerns.
This is an example of the Cochrane Risk of Bias tool in a published article:

example of Cochrane Risk of Bias tool

Cochrane Risk of Bias tool
Quality assessment tool that assesses risk of bias in randomized controlled trials.

The Newcastle-Ottawa Scale assesses risk of bias in non-randomized studies (case-control, cohort studies).
Reviewers assess each study based on three criteria:

Selection of the study groups
Comparability of the groups
Ascertainment of either the exposure or outcome of interest for case-control or cohort studies respectively

This is an example of the Newcastle-Ottawa Scale in a published article:

example of Newcastle Ottawa Scale

Newcastle-Ottawa Scale
Quality assessment tool that assesses risk of bias in non-randomized studies (case-control, cohort studies).