Systematic Review Planning, Study Selection, and Risk of Bias

Planning a systematic review is a fundamental step in conducting a reliable meta-analysis because it establishes a transparent and reproducible framework for identifying, selecting, and evaluating scientific evidence. The process begins with formulating a focused research question using structured frameworks such as PICO (Population, Intervention, Comparison, and Outcome) or PECO (Population, Exposure, Comparison, and Outcome). Researchers then define the study objectives, develop a review protocol, specify research hypotheses where appropriate, and establish explicit inclusion and exclusion criteria. These decisions help keep the review focused on its research objectives and minimize arbitrary choices during the review process.

The next stage involves conducting a systematic literature search using appropriate sources and following a structured procedure to select eligible studies. Students will learn the principles of literature searching, the identification and removal of duplicate records, and the screening of studies based on predefined eligibility criteria. The PRISMA 2020 flow diagram provides a standardized way to document the number of records identified, screened, excluded, and included in the review, thereby improving transparency and reproducibility. In addition, students will learn data extraction, including collecting relevant study characteristics, research methods, sample sizes, outcomes, and statistical results needed for subsequent analysis. Accurate, consistent data extraction is essential to ensure the evidence included in a meta-analysis is suitable for meaningful statistical synthesis.

An equally important component of systematic review planning is assessing risk of bias, the potential for systematic errors in a study's design, conduct, analysis, or reporting to distort its findings. Distinguish risk of bias from statistical limitations, such as small sample sizes, wide confidence intervals, or low statistical power, because these issues affect the precision and certainty of estimates in different ways. Students will explore the principles of risk-of-bias assessment according to study design and understand how methodological weaknesses can influence the validity of individual study findings and the overall conclusions of a meta-analysis. By the end of this session, students should be able to explain the systematic review planning process, describe the procedures for study selection and data extraction, and recognize why evaluating study quality and risk of bias is essential for producing credible, transparent, and scientifically defensible conclusions.