How to Appraise a Systematic Review and Meta Analysis in Clinical Practice
A systematic review is a comprehensive review of primary studies addressing a clearly formulated question using systematic and explicit methods to identify, select and critically appraise relevant research. Meta-analysis is the mathematical synthesis of the primary studies in a systematic review to give a pooled estimate of effect size.
Advantages of systematic reviews and meta-analyses
• Explicit methods are used in identifying and excluding studies based on strict inclusions and exclusions criteria. This limits bias.
• It increases the power of the study by combining different studies, thus increasing the probability of finding a truly significant effect and reducing type II error, i.e. false negative. (This is mainly through a meta-analysis, i.e. quantitative systematic review)
• Large amounts of information can be assimilated quickly by healthcare providers, researchers, and policymakers.
• Prevents or reduces the delay between research discoveries and implementation of effective diagnostic and therapeutic strategies.
• Results of different studies can be formally compared to establish generalisability of findings and consistency of results.
• Reasons for heterogeneity (inconsistencies) can be identified, and new hypothesis can be generated for different subgroups.
• Allows for more objective appraisal of evidence and a more reliable and accurate result due to the methods used.
• Promising research questions to be addressed in future studies may be generated, and the sample size needed in future studies may be calculated accurately.