An Integrative Review (Focus on Purpose Validity Reliability and Applicability)?
J Family Med Prim Intendance. 2013 January-Mar; 2(1): ix–14.
Systematic Reviews and Meta-assay: Agreement the All-time Evidence in Principal Healthcare
S. Gopalakrishnan
Department of Community Medicine, SRM Medical College, Infirmary and Inquiry Centre, Kattankulathur, Tamil Nadu, Republic of india
P. Ganeshkumar
Department of Customs Medicine, SRM Medical Higher, Hospital and Research Centre, Kattankulathur, Tamil Nadu, Bharat
Abstract
Healthcare decisions for individual patients and for public health policies should be informed by the best available inquiry evidence. The practice of testify-based medicine is the integration of individual clinical expertise with the best available external clinical evidence from systematic inquiry and patient'due south values and expectations. Primary care physicians need show for both clinical practice and for public health conclusion making. The evidence comes from proficient reviews which is a state-of-the-fine art synthesis of current evidence on a given research question. Given the explosion of medical literature, and the fact that time is ever deficient, review articles play a vital role in decision making in evidence-based medical do. Given that most clinicians and public health professionals do non accept the time to track down all the original articles, critically read them, and obtain the evidence they demand for their questions, systematic reviews and clinical exercise guidelines may be their best source of evidence. Systematic reviews aim to identify, evaluate, and summarize the findings of all relevant individual studies over a health-related issue, thereby making the bachelor evidence more than accessible to decision makers. The objective of this article is to introduce the primary care physicians about the concept of systematic reviews and meta-analysis, outlining why they are important, describing their methods and terminologies used, and thereby helping them with the skills to recognize and empathise a reliable review which volition be helpful for their day-to-solar day clinical practice and research activities.
Keywords: Evidence-based medicine, meta-analysis, master care, systematic review
Introduction
Bear witness-based healthcare is the integration of best research evidence with clinical expertise and patient values. Greenish denotes, "Using show from reliable research, to inform healthcare decisions, has the potential to ensure all-time practise and reduce variations in healthcare delivery." Still, incorporating research into practice is time consuming, and and then we need methods of facilitating piece of cake access to evidence for busy clinicians.[1] Ganeshkumar et al. mentioned that near half of the private practitioners in India were consulting more 4 h per day in a locality,[2] which explains the difficulty of them in spending fourth dimension in searching evidence during consultation. Ideally, clinical decision making ought to be based on the latest evidence bachelor. However, to go along abreast with the continuously increasing number of publications in health research, a primary healthcare professional person would need to read an insurmountable number of articles every day, covered in more than than 13 million references and over 4800 biomedical and health journals in Medline solitary. With the view to accost this challenge, the systematic review method was developed. Systematic reviews aim to inform and facilitate this process through research synthesis of multiple studies, enabling increased and efficient access to bear witness.[1,3,4]
Systematic reviews and meta-analyses accept get increasingly important in healthcare settings. Clinicians read them to keep up-to-date with their field and they are frequently used as a starting betoken for developing clinical practice guidelines. Granting agencies may crave a systematic review to ensure there is justification for further research and some healthcare journals are moving in this direction.[v]
This article is intended to provide an piece of cake guide to understand the concept of systematic reviews and meta-analysis, which has been prepared with the aim of capacity building for general practitioners and other principal healthcare professionals in research methodology and day-to-twenty-four hours clinical practice.
The purpose of this commodity is to introduce readers to:
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The 2 approaches of evaluating all the available show on an issue i.east., systematic reviews and meta-analysis,
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Discuss the steps in doing a systematic review,
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Introduce the terms used in systematic reviews and meta-analysis,
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Interpret results of a meta-analysis, and
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The advantages and disadvantages of systematic review and meta-analysis.
Awarding
What is the effect of antiviral treatment in dengue fever? Most often a master care physician needs to know convincing answers to questions like this in a primary intendance setting.
To notice out the solutions or answers to a clinical question like this, i has to refer textbooks, ask a colleague, or search electronic database for reports of clinical trials. Doctors demand reliable information on such problems and on the effectiveness of large number of therapeutic interventions, only the information sources are as well many, i.eastward., nearly 20,000 journals publishing 2 million manufactures per year with unclear or confusing results. Because no study, regardless of its type, should be interpreted in isolation, a systematic review is generally the best form of evidence.[vi] So, the preferred method is a practiced summary of inquiry reports, i.e., systematic reviews and meta-assay, which will give prove-based answers to clinical situations.
There are two fundamental categories of research: Primary research and secondary inquiry. Main inquiry is collecting information directly from patients or population, while secondary research is the analysis of data already collected through primary research. A review is an article that summarizes a number of primary studies and may draw conclusions on the topic of involvement which can be traditional (unsystematic) or systematic.
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 event. It synthesizes the results of multiple primary studies related to each other by using strategies that reduce biases and random errors.[vii] To this end, systematic reviews may or may not include a statistical synthesis called meta-analysis, depending on whether the studies are similar enough so that combining their results is meaningful.[8] Systematic reviews are frequently called overviews.
The evidence-based practitioner, David Sackett, defines the following terminologies.[3]
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Review: The general term for all attempts to synthesize the results and conclusions of two or more publications on a given topic.
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Overview: When a review strives to comprehensively identify and rails downwards all the literature on a given topic (also called "systematic literature review").
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Meta-analysis: A specific statistical strategy for assembling the results of several studies into a unmarried estimate.
Systematic reviews attach to a strict scientific design based on explicit, pre-specified, and reproducible methods. Because of this, when carried out well, they provide reliable estimates about the effects of interventions and then that conclusions are defensible. Systematic reviews can also demonstrate where noesis is lacking. This can then be used to guide future research. Systematic reviews are unremarkably carried out in the areas of clinical tests (diagnostic, screening, and prognostic), public health interventions, adverse (damage) furnishings, economic (toll) evaluations, and how and why interventions work.[9]
Cochrane reviews
Cochrane reviews are systematic reviews undertaken by members of the Cochrane Collaboration which is an international not-for-profit organisation that aims to help people to make well-informed decisions about healthcare by preparing, maintaining, and promoting the accessibility of systematic reviews of the furnishings of healthcare interventions.
Cochrane Primary Wellness Care Field is a systematic review of primary healthcare research on prevention, treatment, rehabilitation, and diagnostic test accurateness. The overall aim and mission of the Primary Health Care Field is to promote the quality, quantity, dissemination, accessibility, applicability, and impact of Cochrane systematic reviews relevant to people who work in master intendance and to ensure proper representation in the interests of primary care clinicians and consumers in Cochrane reviews and review groups, and in other entities. This field would serve to coordinate and promote the mission of the Cochrane Collaboration within the primary healthcare disciplines, as well as ensuring that primary care perspectives are adequately represented within the Collaboration.[10]
Meta-analysis
A meta-assay is the combination of data from several contained primary studies that address the aforementioned question to produce a single estimate like the effect of treatment or run a risk gene. Information technology is the statistical analysis of a big collection of analysis and results from individual studies for the purpose of integrating the findings.[11] The term meta-analysis has been used to denote the full range of quantitative methods for research reviews.[12] Meta-analyses are studies of studies.[xiii] Meta-analysis provides a logical framework to a research review where like measures from comparable studies are listed systematically and the available effect measures are combined wherever possible.[14]
The fundamental rationale of meta-analysis is that it reduces the quantity of data by summarizing data from multiple resources and helps to program research as well equally to frame guidelines. It too helps to brand efficient apply of existing data, ensuring generalizability, helping to cheque consistency of relationships, explaining data inconsistency, and quantifies the data. It helps to improve the precision in estimating the risk past using explicit methods.
Therefore, "systematic review" will refer to the entire process of collecting, reviewing, and presenting all available evidence, while the term "meta-analysis" will refer to the statistical technique involved in extracting and combining information to produce a summary result.[15]
Steps in doing systematic reviews/meta-analysis
Following are the six central essential steps while doing systematic review and meta-analysis.[sixteen]
Ascertain the question
This is the most of import part of systematic reviews/meta-analysis. The research question for the systematic reviews may be related to a major public health trouble or a controversial clinical situation which requires acceptable intervention as a possible solution to the present healthcare need of the community. This pace is virtually important since the remaining steps volition be based on this.
Reviewing the literature
This can be done by going through scientific resources such every bit electronic database, controlled clinical trials registers, other biomedical databases, non-English literatures, "gray literatures" (thesis, internal reports, not–peer-reviewed journals, pharmaceutical industry files), references listed in chief sources, raw data from published trials and other unpublished sources known to experts in the field. Amidst the available electronic scientific database, the popular ones are PUBMED, MEDLINE, and EMBASE.
Sift the studies to select relevant ones
To select the relevant studies from the searches, we need to sift through the studies thus identified. The first sift is pre-screening, i.e., to decide which studies to call back in full, and the 2nd sift is option which is to await over again at these studies and determine which are to be included in the review. The next pace is selecting the eligible studies based on similar report designs, year of publication, language, choice among multiple manufactures, sample size or follow-up problems, similarity of exposure, and or treatment and completeness of information.
It is necessary to ensure that the sifting includes all relevant studies like the unpublished studies (desk-bound drawer problem), studies which came with negative conclusions or were published in non-English journals, and studies with small sample size.
Assess the quality of studies
The steps undertaken in evaluating the report quality are early definition of study quality and criteria, setting up a adept scoring organization, developing a standard grade for assessment, computing quality for each study, and finally using this for sensitivity assay.
For example, the quality of a randomized controlled trial can be assessed past finding out the answers to the following questions:
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Was the assignment to the handling groups really random?
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Was the treatment allocation concealed?
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Were the groups similar at baseline in terms of prognostic factors?
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Were the eligibility criteria specified?
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Were the assessors, the intendance provider, and the patient blinded?
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Were the indicate estimates and measure of variability presented for the primary result measure out?
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Did the analyses include intention-to-treat analysis?
Calculate the outcome measures of each study and combine them
Nosotros need a standard measure out of upshot which can be applied to each report on the basis of its issue size. Based on their type of outcome, following are the measures of result: Studies with binary outcomes (cured/not cured) take odds ratio, run a risk ratio; studies with continuous outcomes (blood pressure) have ways, divergence in means, standardized divergence in ways (issue sizes); and survival or time-to-event data have take chances ratios.
Combining studies
Homogeneity of different studies can be estimated at a glance from a woods plot (explained beneath). For example, if the lower conviction interval of every trial is below the upper of all the others, i.due east., the lines all overlap to some extent, and so the trials are homogeneous. If some lines do non overlap at all, these trials may exist said to be heterogeneous.
The definitive exam for assessing the heterogeneity of studies is a variant of Chi-square examination (Mantel–Haenszel test). The final pace is calculating the common estimate and its confidence interval with the original data or with the summary statistics from all the studies. The best estimate of handling event can be derived from the weighted summary statistics of all studies which will be based on weighting to sample size, standard errors, and other summary statistics. Log calibration is used to combine the information to estimate the weighting.
Interpret results: Graph
The results of a meta-analysis are commonly presented as a graph chosen forest plot because the typical woods plots announced as woods of lines. It provides a simple visual presentation of individual studies that went into the meta-analysis at a glance. It shows the variation between the studies and an estimate of the overall consequence of all the studies together.
Forest plot
Meta-analysis graphs tin principally be divided into vi columns [Figure i]. Individual study results are displayed in rows. The starting time column ("study") lists the individual study IDs included in the meta-analysis; usually the get-go author and year are displayed. The 2d column relates to the intervention groups and the third cavalcade to the control groups. The 4th column visually displays the study results. The line in the eye is called "the line of no effect." The weight (in %) in the fifth column indicates the weighting or influence of the study on the overall results of the meta-analysis of all included studies. The higher the percentage weight, the bigger the box, the more influence the study has on the overall results. The sixth column gives the numerical results for each written report (e.1000., odds ratio or relative risk and 95% confidence interval), which are identical to the graphical display in the fourth column. The diamond in the last row of the graph illustrates the overall result of the meta-assay.[four]
Interpretation of meta-analysis[4]
Thus, the horizontal lines represent individual studies. Length of line is the confidence interval (usually 95%), squares on the line represent upshot size (risk ratio) for the study, with expanse of the foursquare being the study size (proportional to weight given) and position equally point estimate (relative take chances) of the study.[7]
For example, the forest plot of the effectiveness of dexamethasone compared with placebo in preventing the recurrence of acute severe migraine headache in adults is shown in Effigy two.[17]
Woods plot of the effectiveness of dexamethasone compared with placebo in preventing the recurrence of acute severe migraine headache in adults[17]
The overall outcome is shown as diamond where the position toward the center represents pooled point judge, the width represents estimated 95% confidence interval for all studies, and the blackness plain line vertically in the heart of plot is the "line of no outcome" (due east.g., relative gamble = 1).
Therefore, when examining the results of a systematic reviews/meta-assay, the following questions should exist kept in mind:
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Were apples combined with oranges?
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Heterogeneity among studies may make any pooled guess meaningless.
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Were all of the apples rotten?
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The quality of a meta-analysis cannot be any better than the quality of the studies it is summarizing.
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Were some apples left on the tree?
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An incomplete search of the literature can bias the findings of a meta-analysis.
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Did the pile of apples amount to more than only a hill of beans?
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Brand sure that the meta-analysis quantifies the size of the outcome in units that yous can empathise.
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Subgroup analysis and sensitivity analysis
Subgroup assay looks at the results of dissimilar subgroups of trials, e.m., by considering trials on adults and children separately. This should exist planned at the protocol stage itself which is based on proficient scientific reasoning and is to be kept to a minimum.
Sensitivity analysis is used to determine how results of a systematic review/meta-analysis change past trivial with data, for example, what is the implication if the exclusion criteria or excluded unpublished studies or weightings are assigned differently. Thus, later on the analysis, if irresolute makes footling or no difference to the overall results, the reviewer's conclusions are robust. If the key findings disappear, then the conclusions need to be expressed more charily.
Advantages of Systematic Reviews
Systematic reviews have specific advantages considering of using explicit methods which limit bias, draw reliable and accurate conclusions, easily deliver required information to healthcare providers, researchers, and policymakers, assistance 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.[xviii]
Limitations in Systematic Reviews/Meta-assay
Equally with all research, the value of a systematic review depends on what was done, what was establish, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers' ability to appraise the strengths and weaknesses of those reviews.[v]
Even though systematic review and meta-assay are considered the all-time evidence for getting a definitive answer to a research question, in that location are certain inherent flaws associated with it, such every bit the location and selection of studies, heterogeneity, loss of data on important outcomes, inappropriate subgroup analyses, conflict with new experimental data, and duplication of publication.
Publication Bias
Publication bias results in it being easier to find studies with a "positive" result.[19] This occurs peculiarly due to inappropriate sifting of the studies where there is always a tendency towards the studies with positive (meaning) outcomes. This result occurs more than commonly in systematic reviews/meta-analysis which demand to be eliminated.
The quality of reporting of systematic reviews is withal not optimal. In a recent review of 300 systematic reviews, few authors reported assessing possible publication bias even though there is overwhelming evidence both for its existence and its impact on the results of systematic reviews. Even when the possibility of publication bias is assessed, there is no guarantee that systematic reviewers take assessed or interpreted it accordingly.[xx]
To overcome sure limitations mentioned above, the Cochrane reviews are currently reported in a format where at the end of every review, findings are summarized in the author's point of view and as well requite an overall pic of the outcome by means of plain linguistic communication summary. This is found to be much helpful to empathize the existing bear witness about the topic more than hands by the reader.
Summary
A systematic review is an overview of primary studies which contains an explicit argument of objectives, materials, and methods, and has been conducted co-ordinate to explicit and reproducible methodology. A meta-analysis is a mathematical synthesis of the results of 2 or more primary studies that addressed the same hypothesis in the aforementioned fashion. Although meta-assay tin increase the precision of a result, information technology 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 discover all relevant studies, critically appraise each report, synthesize the findings from private studies in an unbiased manner, and present balanced of import summary of findings with due consideration of any flaws in the show. Systematic review and meta-analysis is a way of summarizing research prove, which is mostly the best grade of show, and hence positioned at the top of the bureaucracy of evidence.
Systematic reviews can be very useful controlling tools for primary intendance/family unit physicians. They objectively summarize big amounts of information, identifying gaps in medical inquiry, and identifying beneficial or harmful interventions which will be useful for clinicians, researchers, and even for public and policymakers.
Footnotes
Source of Back up: Naught
Conflict of Interest: None declared.
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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3894019/
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