How to Appraise a Systematic Review and Meta Analysis in Clinical Practice
Dr. Sanil Rege is a Consultant Psychiatrist and founder of PsychScene, a platform to enhance psychiatry education and Vita Healthcare, providing high quality mental health care services to the public. He is a Fellow of the Royal Australian and New Zealand College of Psychiatrists and Member of the Royal College of Psychiatrists (UK). His clinical and research interests include psychosis, depression, anxiety, post-traumatic stress disorders, and personality disorders.
As we know, any researcher looks to minimise 4 types of biases in any study. These include selection bias, confounding bias, attrition bias and measurement bias…although some of these biases may not apply [in every study].
In a meta-analysis, one’s not really bothered about the individual study, one’s really concerned about the pooled effect size.
By compiling all these studies, you increase the sample size, you increase the power, therefore, you increase the likelihood of detecting a true difference when one truly exists.
Using an article from the British Journal of Psychiatry, Dr. Sanil Rege explains how to read and analyse published data.
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.
These methods limit 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)
Additionally, it 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.
It 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.
Further tutorials and more in-depth information can be found in the PsychScene online course.
Take Home Messages :
1) A systematic review is a compilation of (usually) pooled RCTs which together give a combined review.
2) A graphical representation of a systematic review is a meta-analysis.
3) Large amounts of information can be assimilated quickly by healthcare providers, researchers, and policymakers.