Analysis and limitations — the author should discuss what the results mean for the area of study being addressed, including how the results might change what is already known about a subject. There should also be a description of the limitations of the study. How to find systematic reviews and meta-analyses of social and psychosocial interventions What is an effect size and what does it mean? How to read a forest plot Checklist for appraising systematic reviews. A meta-analysis is a mathematical synthesis of the results of two or more primary studies that addressed the same hypothesis in the same way.
Although meta-analysis can increase the precision of a result, it is important to ensure that the methods used for the reviews were valid and reliable. High-quality systematic reviews and meta-analyses take great care to find all relevant studies, critically assess each study, synthesize the findings from individual studies in an unbiased manner, and present balanced important summary of findings with due consideration of any flaws in the evidence.
Systematic review and meta-analysis is a way of summarizing research evidence, which is generally the best form of evidence, and hence positioned at the top of the hierarchy of evidence. They objectively summarize large amounts of information, identifying gaps in medical research, and identifying beneficial or harmful interventions which will be useful for clinicians, researchers, and even for public and policymakers.
Source of Support: Nil. Conflict of Interest: None declared. National Center for Biotechnology Information , U. J Family Med Prim Care. Gopalakrishnan and P. Author information Copyright and License information Disclaimer. Address for correspondence: Dr. E-mail: moc. This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3. This article has been cited by other articles in PMC. Abstract Healthcare decisions for individual patients and for public health policies should be informed by the best available research evidence.
Keywords: Evidence-based medicine, meta-analysis, primary care, systematic review. Introduction Evidence-based healthcare is the integration of best research evidence with clinical expertise and patient values. The purpose of this article is to introduce readers to: The two approaches of evaluating all the available evidence on an issue i. Application What is the effect of antiviral treatment in dengue fever?
Terminologies Systematic review A systematic review is a summary of the medical literature that uses explicit and reproducible methods to systematically search, critically appraise, and synthesize on a specific issue. Meta-analysis A meta-analysis is the combination of data from several independent primary studies that address the same question to produce a single estimate like the effect of treatment or risk factor.
Sift the studies to select relevant ones To select the relevant studies from the searches, we need to sift through the studies thus identified. Assess the quality of studies The steps undertaken in evaluating the study quality are early definition of study quality and criteria, setting up a good scoring system, developing a standard form for assessment, calculating quality for each study, and finally using this for sensitivity analysis. For example, the quality of a randomized controlled trial can be assessed by finding out the answers to the following questions: Was the assignment to the treatment groups really random?
Was the treatment allocation concealed? Were the groups similar at baseline in terms of prognostic factors? Were the eligibility criteria specified? Were the assessors, the care provider, and the patient blinded?
Did the analyses include intention-to-treat analysis? Calculate the outcome measures of each study and combine them We need a standard measure of outcome which can be applied to each study on the basis of its effect size.
Combining studies Homogeneity of different studies can be estimated at a glance from a forest plot explained below. Interpret results: Graph The results of a meta-analysis are usually presented as a graph called forest plot because the typical forest plots appear as forest of lines. Forest plot Meta-analysis graphs can principally be divided into six columns [ Figure 1 ]. Open in a separate window. Figure 1. Figure 2.
Subgroup analysis and sensitivity analysis Subgroup analysis looks at the results of different subgroups of trials, e. Advantages of Systematic Reviews Systematic reviews have specific advantages because of using explicit methods which limit bias, draw reliable and accurate conclusions, easily deliver required information to healthcare providers, researchers, and policymakers, help to reduce the time delay in the research discoveries to implementation, improve the generalizability and consistency of results, generation of new hypotheses about subgroups of the study population, and overall they increase precision of the results.
Summary A systematic review is an overview of primary studies which contains an explicit statement of objectives, materials, and methods, and has been conducted according to explicit and reproducible methodology. References 1. Green S. Systematic reviews and meta-analysis. Singapore Med J. Evaluation of computer usage in healthcare among private practitioners of NCT Delhi. Stud Health Technol Inform.
Evidence based medicine: What it is and what it isn't. Ried K. Interpreting and understanding meta-analysis graphs--a practical guide. Aust Fam Physician. PLoS Med. Assessing the quality of research. Systematic reviews: Synthesis of best evidence for clinical decisions.
Ann Intern Med. Clarke M. The cochrane collaboration and systematic reviews. Br J Surg. Centre for Reviews and Dissemination, University of York, In he was retained as a scientific adviser to a legal team acting on oseltamivir. TJ has a potential financial conflict of interest in the drug oseltamivir. In , TJ was a member of three advisory boards for Boerhinger Ingelheim. He is holder of a Cochrane Methods Innovations Fund grant to develop guidance on the use of regulatory data in Cochrane reviews.
TJ was a member of an independent data monitoring committee for a Sanofi Pasteur clinical trial on an influenza vaccine. He has also received income from the publication of a series of toolkit books published by Blackwells.
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