Systematic Reviews in Health

Appraising the Quality of Studies

When reading the full text of each article identified for inclusion in the review as part of the Data Extraction process, apply a Critical Appraisal Tool (CAT) to each study selected for inclusion. 

Generally, the critical appraisal step will consider:

• Question - Does this study address a clearly focused question?

• Methodological quality - Did the study use valid methods to address this question?  To what extent do the study design and conduct eliminate the potential for systematic error (bias)?

• Precision – What is the likelihood of random errors? (Often depicted as the confidence interval around the result)

• External validity - Are these valid, important results applicable to my patient or population?

It is best however, to use the critical appraisal checklist or worksheet that is most appropriate to the study type included in the Systematic Review.  

See the critical appraisal guides, checklists and worksheets below.

Checklists and Worksheets

These can be downloaded and used to assess the applicability, reliability and validity of published research:

Quality Scales

JADAD - Jadad quality assessment scale for rating Randomized Controlled Trials1 - permits a rank of the studies in the Systematic Review allowing a score to be calculated, based on quality.

1. Jadad, A., et al. (1996). Assessing the quality of reports of randomized clinical trials: is blinding necessary?. Controlled Clinical Trials, 17(1), 1-12. Available: doi:10.1016/0197-2456(95)00134-4