Steps in systematic review (Part 1)

Systematic reviews are essential tools for synthesising evidence, guiding decision-making, and advancing scientific understanding.

This guide outlines the key steps involved in conducting a systematic review, from formulating a research question to performing an effective literature search.

Understanding the Literature Review Process

Reviewing the literature involves:

• Deciding which documents to include.

• Understanding how authors describe their research.

• Evaluating research methods and results.

• Writing a synthesis that combines content with critical analysis.

Step 1: Framing a Research Question Using PICO

The PICO framework helps define the scope and focus of a systematic review:

• P: Patient or Problem (e.g., children with fever).

• I: Intervention (e.g., paracetamol).

• C: Comparison (e.g., ibuprofen).

• O: Outcome (e.g., reduction in fever).

A well-structured PICO question ensures clarity and relevance in selecting studies.

Step 2: Setting Inclusion and Exclusion Criteria

To ensure comprehensiveness and objectivity, studies must meet predefined criteria, including:

• Study Date: Recent or historical studies.

• Exposure of Interest: Specific interventions or conditions.

• Geographic Location: Studies from particular regions.

• Language: Whether non-English studies are included.

• Participants: Specific populations (e.g., children, elderly).

• Peer Review Status: Published peer-reviewed studies.

• Reported Outcomes: Relevance to the research question.

• Study Design: Randomised controlled trials, cohort studies, etc.

Step 3: Conducting an Article Search

Once criteria are set, relevant studies must be identified using structured search strategies.

1. Using Boolean Logic for Effective Searches

Boolean logic, developed by George Boole, helps refine database searches using three key operators:

• AND: Requires both terms (e.g., diabetes AND exercise).

• OR: Includes any of the terms (e.g., faculty OR teachers OR professors).

• NOT: Excludes unwanted terms (e.g., students NOT dental).

Brackets ( ) help group synonyms together (e.g., (fever OR febrile) AND (paracetamol OR acetaminophen)).

2. Using Alternative Terms and Synonyms

To maximise search results, include different terms for the same concept.

For example:

• Fever → febrile, high temperature

• Paracetamol → acetaminophen, Panadol

3. Constructing a Boolean Search

For the question: Is Vitamin C helpful in treating the flu?

• P (Problem): (influenza OR flu OR orthomyxovirus)

• I (Intervention): (vitamin C OR ascorbic acid OR orange juice)

• O (Outcome): (treatment OR recovery OR success)

• Final Search Query: (influenza OR flu) AND (vitamin C OR ascorbic acid) AND (treatment OR therapy OR recovery)

4. Advanced Search Techniques

• Phrase Searching: Use quotes to search for exact phrases (e.g., “job satisfaction”).

• Truncation and Wildcards: Use symbols to capture word variations.

• Asterisk (*): responsib** → responsible, responsibility.

• Question Mark (?): Replaces a single character (e.g., wom?n → woman, women).

• Search Limits: Most databases allow filtering by language, article type, publication date, and more.

Step 4: Searching Multiple Databases

Different databases index unique journals, so using multiple sources ensures comprehensive coverage.

• PubMed: Biomedical and life sciences.

• Scopus: Broad scientific coverage.

• Web of Science: Citation analysis and impact tracking.

• EBSCOhost, ScienceDirect, OvidSP: Field-specific literature databases.

Using broader terms increases search results, while narrower terms enhance relevance. Balancing these factors is key to an effective literature search.

In the next part, we will explore data extraction, quality assessment, and synthesising results in systematic reviews.