Introduction:
Conducting a systematic review involves several crucial steps to ensure the quality and reliability of the findings. One of these critical stages is filtering studies and establishing inclusion and exclusion criteria. This process determines which studies will be included in the review and which ones will be excluded based on predefined criteria. In this article, we will provide beginners with a practical guide to navigating this essential step, along with examples to illustrate the process, including the use of Rayyan software for filtration.
Understanding Inclusion and Exclusion Criteria: Inclusion criteria are the characteristics that studies must have to be considered for inclusion in the systematic review. These criteria typically relate to the research question, population, intervention/exposure, comparison, and outcomes (PICOS). On the other hand, exclusion criteria are used to eliminate studies that do not meet specific standards or are not relevant to the research question.
Developing Inclusion and Exclusion Criteria:
- Begin by clearly defining the research question and objectives of the systematic review.
- Identify key components of the PICOS framework: Population, Intervention/Exposure, Comparison, Outcomes, and Study design.
- Determine specific criteria for each component based on the research question and objectives.
- Consider factors such as study design, language, publication date, and geographical location.
- Ensure that the criteria are clear, measurable, and feasible to apply consistently across all studies.
Practical Filtration Methods: One practical way to filter studies is by using dedicated software like Rayyan. Rayyan allows researchers to import search results from databases, screen titles and abstracts, and collaborate with team members in the screening process. Researchers can create inclusion and exclusion criteria within Rayyan and systematically go through each study to determine its eligibility for inclusion in the review.
Applying Inclusion and Exclusion Criteria:
- Import search results into Rayyan and screen titles and abstracts based on predefined inclusion and exclusion criteria.
- Review full-text articles of potentially relevant studies to assess eligibility further.
- Use Rayyan's features to tag studies as included or excluded and record reasons for decisions.
- Collaborate with team members by sharing screening tasks and discussing discrepancies.
- Use Rayyan's reporting features to generate summaries of included and excluded studies for transparency and reproducibility.
Examples: Example 1: Research question - "Does exercise reduce the risk of cardiovascular disease in adults?" Inclusion criteria:
- Population: Adults aged 18 years and above.
- Intervention: Any form of exercise intervention.
- Comparison: No exercise or sedentary lifestyle.
- Outcomes: Incidence or prevalence of cardiovascular disease.
- Study design: Randomized controlled trials (RCTs), cohort studies. Exclusion criteria:
- Studies involving children or adolescents.
- Studies focusing on non-exercise interventions.
- Studies without relevant outcome measures.
- Case reports, editorials, and reviews.
Example 2: Research question - "What are the psychological effects of social media use in adolescents?" Inclusion criteria:
- Population: Adolescents aged 10-19 years.
- Intervention/Exposure: Use of social media platforms.
- Comparison: Different levels or types of social media use.
- Outcomes: Psychological well-being, depression, anxiety, self-esteem.
- Study design: Observational studies (cross-sectional, cohort), intervention studies. Exclusion criteria:
- Studies involving adults or children outside the specified age range.
- Studies focusing solely on physical health outcomes.
- Studies not assessing the impact of social media use on psychological factors.
- Studies with inadequate methodological quality.
Conclusion: Filtering studies and setting inclusion and exclusion criteria are essential steps in conducting a systematic review. Utilizing tools like Rayyan can streamline the filtration process and enhance collaboration among team members. By adhering to a systematic approach and using practical methods, beginners can effectively navigate this process and produce robust review findings.