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Systematic Reviews & Other Syntheses

Introduction

Once included studies have been selected for a synthesis, the next step is to extract key details from the studies. This process, known as data extraction, is described in detail in the module linked on the right.
It is strongly recommended that Queen's reviewers take advantage of the institutional subscription to Covidence review software to facilitate data extraction, including: creating and completing a data extraction template, accessing reviewer consensus and resolving conflicts, and creating and customizing tables.

Common Types of Data to Extract

The typical categories of data extracted in systematic reviews include [1,2]:

  • Extraction details (e.g., reference ID, name of extractor);

  • Study characteristics (e.g., authors, year, country);

  • Methodology;

  • Participant details (e.g., demographics);

  • Intervention/exposure and comparator details;

  • Outcomes measured;

  • Results (e.g., effect sizes, confidence intervals);

  • Miscellaneous (e.g., comments from review team).

Reporting Standards

Before beginning the extraction process, check the reporting guidelines specific to your review type. For example, PRISMA requires you to report the following[3]:

Image of the PRISMA 2020 Checklist showing data collection process and data items.

Bibliography

  1. Li T, Higgins JPT, Deeks JJ. Chapter 5: Collecting data [last updated October 2019]. In: Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions version 6.5. Cochrane, 2024. Available from cochrane.org/handbook.
  2. Munn Z, Tufanaru C, Aromataris E. Data extraction and synthesis: the steps following study selection in a systematic review. American Journal of Nursing. 2014 Jul;114(7):49-54. doi: 10.1097/01.NAJ.0000451683.66447.89.
  3. Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, Shamseer L, Tetzlaff JM, Akl EA, Brennan SE, Chou R, Glanville J, Grimshaw JM, Hróbjartsson A, Lalu MM, Li T, Loder EW, Mayo-Wilson E, McDonald S, McGuinness LA, Stewart LA, Thomas J, Tricco AC, Welch VA, Whiting P, Moher D. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. J Clin Epidemiol. 2021 Jun;134:178-189. doi: 10.1016/j.jclinepi.2021.03.001.

Training Module

An inter-professional team led by Queen's has set out to develop an open access module series titled The Essentials of Conducting Systematic Reviews to introduce researchers to all stages of the systematic review process.

Check out Module 5: Extracting Data.

 

Resource Spotlight

Covidence now offers a practical guide for: Data Extraction for Intervention Systematic Reviews.