Conducting Systematic Reviews: An Evidenced‑Based Approach

Dr Liris Benjamin • Dr Ektor Polykandriotis • Ross Academic Research Society (RARS) 

Conducting Systematic Reviews: An Evidence‑Based Approach Dr Liris Benjamin^{1, 2} • Dr Ektor Polykandriotis^{1, 2} • Ross Academic Research Society (RARS)¹, Ross University School of Medicine² 

Abstract Systematic reviews synthesize high‑quality research that provides evidence to inform clinical and policy decision‑making. The process utilizes explicit, reproducible methods and often incorporates meta‑analysis to quantitatively summarize results (Page et al., 2021; Higgins et al., 2024). This article outlines the hierarchy of evidence, distinguishes systematic from narrative reviews, introduces meta‑analysis, and provides a stepwise guide to conducting a systematic review, referencing key methodological frameworks including PRISMA, the Cochrane Handbook, GRADE, CASP, JBI, and ROBINS‑I (Guyatt et al., 2025; Sterne et al., 2016). 

Introduction Evidence‑based medicine emphasizes decisions grounded in comprehensive, transparent syntheses of available research (Higgins et al., 2024). Systematic reviews—particularly those that follow PRISMA 2020 guidance—minimize bias and increase precision through structured, reproducible processes (Page et al., 2021). 

Hierarchy of Evidence Systematic reviews and meta‑analyses of randomized trials sit at the top of the evidence hierarchy, followed by randomized controlled trials, observational studies, case series, and expert opinion (Higgins et al., 2024; Schünemann et al., 2023). 

What is a Narrative Review? 

A narrative review (also referred to as a traditional or expert review) is a qualitative, interpretive synthesis of the literature that provides a broad, contextualized overview of a topic without a predefined protocol or exhaustive search strategy. Rather than aiming to identify all eligible studies or quantify effect sizes, narrative reviews selectively integrate key literature to explain concepts, trace theoretical development, and offer critical perspectives. They are flexible and author-driven, allowing synthesis across heterogeneous evidence, integration of interdisciplinary insights, and the development of conceptual or theoretical frameworks (Baethge et al., 2019; Green et al., 2006). Narrative reviews are particularly well suited for exploring complex or emerging topics, generating new models, and translating evidence into clinically meaningful or educationally relevant interpretations (Ferrari, 2015). 

What Is a Systematic Review? A systematic review is a comprehensive, protocol‑driven synthesis of all evidence meeting predefined eligibility criteria (Higgins et al., 2024). PRISMA 2020 provides standardized reporting requirements and the flow diagram used to document study selection (Page et al., 2021; PRISMA Statement, 2020). 

Empirical evidence suggests that narrative reviews constitute the majority of published review articles, accounting for approximately 70–75% of the literature, whereas systematic reviews represent about 25–30% (Baethge et al., 2019). Narrative reviews are optimally used when the goal is theory building, contextual understanding, or synthesis across diverse methodologies rather than answering narrowly defined effectiveness questions (Green et al., 2006). They are widely published in clinical and practice-oriented journals, theoretical and conceptual journals in psychology and education, and medical education or simulation journals, as well as in invited “state-of-the-art” review sections. In contrast to systematic reviews, which are designed to answer focused questions about effectiveness, narrative reviews are best suited to address broader interpretive questions such as conceptual meaning and integration across domains (Ferrari, 2015). 

Narrative Review vs Systematic Review  Narrative reviews provide a general overview or context and often lack transparency in study selection and appraisal.  They are broad, flexible summary of a topic compared with  a systematic review which  follows a rigid, predefined protocol to answer a specific research question with minimal bias. Further when heterogeneity is acceptable, quantitative synthesis via meta‑analysis can further enhance precision (Higgins et al., 2024). 

Meta‑Analysis: Quantitative Synthesis Meta‑analysis commonly uses risk ratios or odds ratios for dichotomous outcomes, and mean differences or standardized mean differences for continuous outcomes (Higgins et al., 2024).   Forest plots and funnel plots are complementary graphical tools for meta-analyses.  Forest plots reveal individual study effects and overall pooled results to show heterogeneity.  On the other hand, funnel plots (usually requiring > 10 studies) are scatterplots designed to detect publication bias by visualizing asymmetry in study results.  Typically a funnel plot resembles an inverted funnel.  An absence bias results in a symmetrical shape whereas asymmetry suggests potential bias of study the results. 

Steps in Conducting a Systematic Review 

 1) Formulate a focused research question using  PICO framework.  (PICO – Population, Intervention, Comparator, Outcomes). Other abbreviations utilized include PICOTS - , Timing  and Setting  or PICOD (study Design. However they all o assist in creating the  

2) Develop and register a protocol. For example, Prospective registration in PROSPERO enhances transparency. 

3) Perform a comprehensive search. Utilize multi‑database strategies, grey literature searches, and registry screening. 

 4) Select studies and extract data. Dual‑reviewer screening and extraction reduce error 

  5) Assess risk of bias.  

6) Synthesize and present results. Provide narrative and/or quantitative synthesis; when meta‑analysis is used, include a GRADE Summary of Findings table to communicate certainty of evidence  

7) Explore heterogeneity and bias. Use subgroup analysis or meta‑regression as planned; evaluate funnel plot asymmetry cautiously. 

 8) Interpret and conclude. Integrate effect size, heterogeneity, risk of bias, and GRADE certainty ratings 

Balk, E. M., & Bonis, P. A. L. (2025).  

Common Pitfalls and Best Practices Barriers to a good systematic review include incomplete searches, insufficient protocol detail, and inappropriate pooling. Adherence to PRISMA, Cochrane, GRADE, and validated appraisal tools strengthens rigor and transparency (Higgins et al., 2024; Page et al., 2021; Guyatt et al., 2025). 

Conclusion Systematic reviews, when grounded in robust methodology, provide the most reliable evidence to inform policy and practice. Structured frameworks—PICO, PRISMA, Cochrane standards, ROBINS‑I, CASP/JBI tools, and GRADE—ensure comprehensive appraisal and transparent synthesis (Higgins et al., 2024; Schünemann et al., 2023). 

References  

Balk, E. M., & Bonis, P. A. L. (2025). Systematic review and meta-analysis. UpToDate. https://www.uptodate.com/contents/systematic-review-and-meta-analysis 

Critical Appraisal Skills Programme. (2020). CASP checklists. https://casp-uk.net/casp-tools-checklists/ 

Cochrane Bias Methods Group. (n.d.). ROBINS-I (updated resources). https://methods.cochrane.org/bias/risk-bias-non-randomized-studies-interventions 

Cochrane Library. (n.d.). About PICO. https://www.cochranelibrary.com/about-pico 

GRADE Working Group. (2013). GRADE handbook. https://gradepro.org/handbook/ 

Guyatt, G., Yao, L., Murad, M. H., Hultcrantz, M., Agoritsas, T., De Beer, H., ... Brignardello-Petersen, R. (2025). Core GRADE 6: Presenting the evidence in summary of findings tables. BMJ, 389, e083866. https://doi.org/10.1136/bmj-2024-083866 

Higgins, J. P. T., Li, T., & Deeks, J. J. (2024). Chapter 6: Choosing effect measures and computing estimates of effect. In J. P. T. Higgins, J. Thomas, J. Chandler, M. Cumpston, T. Li, M. J. Page, & V. Welch (Eds.), Cochrane handbook for systematic reviews of interventions (Version 6.5). https://www.cochrane.org/authors/handbooks-and-manuals/handbook/current/chapter-06 

Higgins, J. P. T., Thomas, J., Chandler, J., Cumpston, M., Li, T., Page, M. J., & Welch, V. (Eds.). (2024). Cochrane handbook for systematic reviews of interventions (Version 6.5). Cochrane. https://www.cochrane.org/authors/handbooks-and-manuals/handbook 

Joanna Briggs Institute. (2020). JBI critical appraisal tools. https://jbi.global/critical-appraisal-tools 

National Institute for Health Research. (2026). PROSPERO: International prospective register of systematic reviews. https://www.crd.york.ac.uk/PROSPERO/ 

Page, M. J., McKenzie, J. E., Bossuyt, P. M., Boutron, I., Hoffmann, T. C., Mulrow, C. D., ... Moher, D. (2021). The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. BMJ, 372, n71. https://doi.org/10.1136/bmj.n71 

PRISMA Statement. (2020). PRISMA 2020 flow diagram templates. https://www.prisma-statement.org 

Schünemann, H. J., Higgins, J. P. T., Vist, G. E., Glasziou, P., Akl, E. A., Skoetz, N., & Guyatt, G. H. (2023). Chapter 14: Completing ‘Summary of findings’ tables and grading the certainty of the evidence. In J. P. T. Higgins, J. Thomas, J. Chandler, M. Cumpston, T. Li, M. J. Page, & V. Welch (Eds.), Cochrane handbook for systematic reviews of interventions (Version 6.5). https://www.cochrane.org/authors/handbooks-and-manuals/handbook/current/chapter-14 

Sterne, J. A. C., Hernán, M. A., Reeves, B. C., Savović, J., Berkman, N. D., Viswanathan, M., ... Higgins, J. P. T. (2016). ROBINS-I: A tool for assessing risk of bias in non-randomised studies of interventions. BMJ, 355, i4919. https://doi.org/10.1136/bmj.i4919 

Sterne, J. A. C., Sutton, A. J., Ioannidis, J. P. A., Terrin, N., Jones, D. R., Lau, J., ... Higgins, J. P. T. (2011). Recommendations for examining and interpreting funnel plot asymmetry. BMJ, 343, d4002. https://doi.org/10.1136/bmj.d4002 

Baethge, C., Goldbeck-Wood, S., & Mertens, S. (2019). SANRA—a scale for the quality assessment of narrative review articles. Research Integrity and Peer Review, 4(5). https://doi.org/10.1186/s41073-019-0064-8 

Ferrari, R. (2015). Writing narrative style literature reviews. Medical Writing, 24(4), 230–235. https://doi.org/10.1179/2047480615Z.000000000329 

Green, B. N., Johnson, C. D., & Adams, A. (2006). Writing narrative literature reviews for peer-reviewed journals: Secrets of the trade. Journal of Chiropractic Medicine, 5(3), 101–117. https://doi.org/10.1016/S0899-3467(07)60142-6 

Note: This article was developed with the assistance of AI tools (such as ChatGPT) for drafting and editing support. All content has been reviewed and verified by the author. 

 Ross Academic Research Society Blog https://www.rusmrars.com, April 2026