Guides: Systematic Reviews: 5. Extract data & assess quality

Extract data

Data extraction allows the team to see the data from each individual research study in a comparative fashion, and at the same time.

Devise a form tailored to your research question to ensure you obtain all relevant information from each included study. This form will generally include details of study characteristics, participant characteristics, intervention and setting, and results and replicate aspects of your PICO question. You will need to pilot and refine this form before your final search. Ideally this form should be electronic to minimize transcription errors.

Microsoft Excel is familiar software that may be used to create a form. Alternatively, you can use the editable template from Cochrane linked below:

Data Extraction Form (Cochrane Review Group)
Edit this form to suit the needs of your systematic review.

Assess quality of included studies

Critical appraisal is a systematic analysis of research articles to determine the strength of the evidence in reference to your clinical question.

Tools and checklists exist to grade levels of evidence or assess the quality of quantitative and qualitative studies. The Cochrane Handbook for Systematic Reviews of Interventions strongly encourages researchers to use the Cochrane Risk of Bias Tool 2.0 for Cochrane reviews (Higgins, 2019, Section 8.1).

The following are common grading scales and checklists:

Cochrane RoB 2.0 (Risk of Bias) Tool
This is the newly revised Cochrane Collaboration Risk of Bias tool, released in August 2019. The Risk of Bias tool developed by the Cochrane Collaboration evaluates studies in several domains, including selection bias, performance bias, attrition bias, reporting bias, etc. It ONLY can be used for randomized control trials (RCTs).
Joanna Briggs Institute Critical Appraisal Tools
Provides access to critical appraisal tools for different types of studies.
CASP Appraisal Checklists
This set of eight critical appraisal tools are designed to be used when reading research, these include tools for Systematic Reviews, Randomised Controlled Trials, Cohort Studies, Case Control Studies, Economic Evaluations, Diagnostic Studies, Qualitative studies and Clinical Prediction Rule.
STROBE Checklists
STROBE stands for an international, collaborative initiative of epidemiologists, methodologists, statisticians, researchers and journal editors involved in the conduct and dissemination of observational studies, with the common aim of STrengthening the Reporting of OBservational studies in Epidemiology.
Aboriginal and Torres Strait Islander Quality Appraisal Tool (QAT)
This critical appraisal tool offers guidance on how validity or contextual relevance should be assessed for Indigenous populations and cultural contexts.