Is a Systematic Review Considered Evidence Based Practice

• Journal List
• J Family unit Med Prim Care
• v.ii(1); Jan-Mar 2013
• PMC3894019

J Family Med Prim Care. 2013 Jan-Mar; 2(i): ix–14.

Systematic Reviews and Meta-assay: Understanding the Best Show in Primary Healthcare

S. Gopalakrishnan

Section of Community Medicine, SRM Medical College, Infirmary and Enquiry Centre, Kattankulathur, Tamil Nadu, Bharat

P. Ganeshkumar

Department of Community Medicine, SRM Medical College, Hospital and Research Centre, Kattankulathur, Tamil Nadu, India

Abstruse

Healthcare decisions for individual patients and for public health policies should exist informed by the best available inquiry evidence. The practice of evidence-based medicine is the integration of individual clinical expertise with the best available external clinical evidence from systematic research and patient'due south values and expectations. Master care physicians need bear witness for both clinical practice and for public health determination making. The show comes from proficient reviews which is a state-of-the-art synthesis of current evidence on a given research question. Given the explosion of medical literature, and the fact that time is ever scarce, review articles play a vital role in decision making in prove-based medical exercise. Given that nearly clinicians and public health professionals practice not accept the time to track downwards all the original articles, critically read them, and obtain the testify they need for their questions, systematic reviews and clinical exercise guidelines may be their best source of bear witness. Systematic reviews aim to identify, evaluate, and summarize the findings of all relevant individual studies over a health-related upshot, thereby making the available evidence more than accessible to determination makers. The objective of this commodity is to innovate the primary care physicians well-nigh the concept of systematic reviews and meta-assay, outlining why they are of import, describing their methods and terminologies used, and thereby helping them with the skills to recognize and understand a reliable review which will be helpful for their day-to-day clinical practice and enquiry activities.

Keywords: Bear witness-based medicine, meta-analysis, primary care, systematic review

Introduction

Testify-based healthcare is the integration of best inquiry evidence with clinical expertise and patient values. Green denotes, "Using evidence from reliable research, to inform healthcare decisions, has the potential to ensure all-time practice and reduce variations in healthcare delivery." Even so, incorporating research into practice is time consuming, and and then we need methods of facilitating easy access to evidence for decorated clinicians.[1] Ganeshkumar et al. mentioned that nearly half of the private practitioners in India were consulting more than 4 h per day in a locality,[2] which explains the difficulty of them in spending time in searching evidence during consultation. Ideally, clinical decision making ought to be based on the latest testify bachelor. Nonetheless, to keep beside with the continuously increasing number of publications in wellness inquiry, a primary healthcare professional person would need to read an insurmountable number of manufactures every day, covered in more than 13 million references and over 4800 biomedical and health journals in Medline alone. With the view to address 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 evidence.[ane,3,four]

Systematic reviews and meta-analyses have become increasingly important in healthcare settings. Clinicians read them to keep up-to-date with their field and they are oft used as a starting bespeak for developing clinical practice guidelines. Granting agencies may require a systematic review to ensure at that place is justification for further research and some healthcare journals are moving in this direction.[v]

This article is intended to provide an easy 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 master healthcare professionals in research methodology and day-to-day clinical practice.

The purpose of this commodity is to innovate readers to:

1. The two approaches of evaluating all the bachelor bear witness on an consequence i.e., systematic reviews and meta-assay,

2. Talk over the steps in doing a systematic review,

3. Introduce the terms used in systematic reviews and meta-analysis,

4. Interpret results of a meta-assay, and

5. The advantages and disadvantages of systematic review and meta-assay.

Application

What is the effect of antiviral treatment in dengue fever? Most oftentimes a primary care physician needs to know convincing answers to questions like this in a principal care setting.

To notice out the solutions or answers to a clinical question like this, one has to refer textbooks, ask a colleague, or search electronic database for reports of clinical trials. Doctors need reliable information on such bug and on the effectiveness of large number of therapeutic interventions, just the information sources are too many, i.eastward., nearly 20,000 journals publishing two million articles per twelvemonth with unclear or confusing results. Because no study, regardless of its type, should exist interpreted in isolation, a systematic review is generally the best class of show.[vi] So, the preferred method is a skilful summary of inquiry reports, i.due east., systematic reviews and meta-analysis, which will give evidence-based answers to clinical situations.

In that location are two fundamental categories of research: Main research and secondary research. Primary research is collecting data directly from patients or population, while secondary research is the assay of data already collected through primary enquiry. A review is an commodity that summarizes a number of chief studies and may describe 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 consequence. It synthesizes the results of multiple primary studies related to each other by using strategies that reduce biases and random errors.[7] To this finish, systematic reviews may or may not include a statistical synthesis called meta-assay, depending on whether the studies are like 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]

• Review: The general term for all attempts to synthesize the results and conclusions of two or more publications on a given topic.

• Overview: When a review strives to comprehensively identify and track downwardly all the literature on a given topic (likewise called "systematic literature review").

• Meta-analysis: A specific statistical strategy for assembling the results of several studies into a single 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 nigh the furnishings of interventions and then that conclusions are defensible. Systematic reviews can also demonstrate where knowledge is lacking. This tin can so be used to guide time to come research. Systematic reviews are usually carried out in the areas of clinical tests (diagnostic, screening, and prognostic), public health interventions, adverse (impairment) effects, economic (cost) evaluations, and how and why interventions work.[ix]

Cochrane reviews

Cochrane reviews are systematic reviews undertaken past members of the Cochrane Collaboration which is an international not-for-profit organization that aims to aid people to make well-informed decisions about healthcare by preparing, maintaining, and promoting the accessibility of systematic reviews of the effects of healthcare interventions.

Cochrane Primary Health 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 main care and to ensure proper representation in the interests of principal 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 fairly represented within the Collaboration.[10]

Meta-analysis

A meta-analysis is the combination of data from several independent principal studies that address the same question to produce a single estimate similar the consequence of treatment or risk cistron. It is the statistical analysis of a large 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.[13] Meta-analysis provides a logical framework to a research review where similar measures from comparable studies are listed systematically and the bachelor effect measures are combined wherever possible.[xiv]

The primal rationale of meta-analysis is that information technology reduces the quantity of data by summarizing data from multiple resources and helps to programme inquiry as well as to frame guidelines. Information technology also helps to make efficient utilise of existing data, ensuring generalizability, helping to check consistency of relationships, explaining data inconsistency, and quantifies the data. It helps to improve the precision in estimating the chance by using explicit methods.

Therefore, "systematic review" will refer to the entire process of collecting, reviewing, and presenting all bachelor evidence, while the term "meta-assay" will refer to the statistical technique involved in extracting and combining data to produce a summary consequence.[fifteen]

Steps in doing systematic reviews/meta-assay

Following are the six fundamental essential steps while doing systematic review and meta-analysis.[16]

Define the question

This is the virtually of import part of systematic reviews/meta-analysis. The research question for the systematic reviews may be related to a major public wellness problem or a controversial clinical situation which requires acceptable intervention as a possible solution to the present healthcare demand of the community. This step is most important since the remaining steps will be based on this.

Reviewing the literature

This can be washed by going through scientific resource such as 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 principal sources, raw information from published trials and other unpublished sources known to experts in the field. Among the bachelor 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 showtime sift is pre-screening, i.e., to decide which studies to retrieve in full, and the second sift is pick which is to look once more at these studies and decide which are to be included in the review. The next pace is selecting the eligible studies based on similar study designs, year of publication, language, choice among multiple articles, sample size or follow-up issues, similarity of exposure, and or treatment and completeness of information.

It is necessary to ensure that the sifting includes all relevant studies similar the unpublished studies (desk drawer problem), studies which came with negative conclusions or were published in non-English journals, and studies with pocket-size sample size.

Assess the quality of studies

The steps undertaken in evaluating the report quality are early definition of study quality and criteria, setting upwards a good scoring system, developing a standard form for assessment, calculating quality for each study, and finally using this for sensitivity assay.

For example, the quality of a randomized controlled trial tin can be assessed by finding out the answers to the following questions:

1. Was the consignment to the treatment groups actually random?

2. Was the treatment allotment concealed?

3. Were the groups similar at baseline in terms of prognostic factors?

4. Were the eligibility criteria specified?

5. Were the assessors, the care provider, and the patient blinded?

6. Were the bespeak estimates and measure of variability presented for the primary outcome measure?

7. Did the analyses include intention-to-treat analysis?

Calculate the outcome measures of each study and combine them

We need a standard measure of effect which tin exist practical to each report on the basis of its result size. Based on their blazon of upshot, post-obit are the measures of result: Studies with binary outcomes (cured/not cured) have odds ratio, risk ratio; studies with continuous outcomes (claret pressure) have means, difference in means, standardized deviation in means (effect sizes); and survival or time-to-event data have chance ratios.

Combining studies

Homogeneity of different studies can exist estimated at a glance from a forest plot (explained below). For example, if the lower confidence interval of every trial is below the upper of all the others, i.due east., the lines all overlap to some extent, then the trials are homogeneous. If some lines practise not overlap at all, these trials may be said to exist heterogeneous.

The definitive test for assessing the heterogeneity of studies is a variant of Chi-square test (Mantel–Haenszel test). The concluding step is computing the mutual approximate and its confidence interval with the original data or with the summary statistics from all the studies. The best guess of treatment result tin 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 scale is used to combine the data to estimate the weighting.

Translate results: Graph

The results of a meta-analysis are normally presented every bit a graph called forest plot because the typical forest plots appear every bit forest of lines. Information technology provides a simple visual presentation of private studies that went into the meta-analysis at a glance. It shows the variation between the studies and an estimate of the overall result of all the studies together.

Wood plot

Meta-analysis graphs can principally be divided into six columns [Effigy ane]. Individual study results are displayed in rows. The beginning cavalcade ("study") lists the individual study IDs included in the meta-analysis; usually the first author and yr are displayed. The 2d column relates to the intervention groups and the 3rd cavalcade to the control groups. The quaternary column visually displays the study results. The line in the center is called "the line of no effect." The weight (in %) in the 5th column indicates the weighting or influence of the study on the overall results of the meta-assay of all included studies. The higher the pct weight, the bigger the box, the more influence the study has on the overall results. The sixth column gives the numerical results for each study (e.1000., odds ratio or relative risk and 95% conviction interval), which are identical to the graphical brandish in the fourth column. The diamond in the final row of the graph illustrates the overall outcome of the meta-analysis.[four]

Interpretation of meta-analysis[4]

Thus, the horizontal lines represent private studies. Length of line is the confidence interval (ordinarily 95%), squares on the line represent issue size (risk ratio) for the study, with area of the foursquare being the written report size (proportional to weight given) and position every bit indicate estimate (relative adventure) of the report.[seven]

For case, 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 Figure 2.[17]

Forest plot of the effectiveness of dexamethasone compared with placebo in preventing the recurrence of acute astringent migraine headache in adults[17]

The overall upshot is shown as diamond where the position toward the center represents pooled point gauge, the width represents estimated 95% confidence interval for all studies, and the black patently line vertically in the eye of plot is the "line of no effect" (e.chiliad., relative run a risk = ane).

Therefore, when examining the results of a systematic reviews/meta-analysis, the post-obit questions should exist kept in listen:

1. Were apples combined with oranges?

   • Heterogeneity among studies may brand whatsoever pooled estimate meaningless.

2. Were all of the apples rotten?

   • The quality of a meta-assay cannot be any better than the quality of the studies it is summarizing.

3. Were some apples left on the tree?

   • An incomplete search of the literature can bias the findings of a meta-analysis.

4. Did the pile of apples amount to more than than merely a hill of beans?

   • Brand sure that the meta-analysis quantifies the size of the effect in units that you can understand.

Subgroup analysis and sensitivity analysis

Subgroup analysis looks at the results of different subgroups of trials, due east.thou., by because trials on adults and children separately. This should be planned at the protocol stage itself which is based on good scientific reasoning and is to exist kept to a minimum.

Sensitivity analysis is used to decide how results of a systematic review/meta-analysis change by trivial with information, for instance, what is the implication if the exclusion criteria or excluded unpublished studies or weightings are assigned differently. Thus, later on the assay, if irresolute makes petty or no deviation to the overall results, the reviewer'due south conclusions are robust. If the fundamental findings disappear, and so the conclusions need to be expressed more charily.

Advantages of Systematic Reviews

Systematic reviews have specific advantages because of using explicit methods which limit bias, describe reliable and accurate conclusions, easily deliver required information to healthcare providers, researchers, and policymakers, help to reduce the time filibuster in the research discoveries to implementation, better the generalizability and consistency of results, generation of new hypotheses about subgroups of the study population, and overall they increment precision of the results.[18]

Limitations in Systematic Reviews/Meta-analysis

As with all research, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. Every bit with other publications, the reporting quality of systematic reviews varies, limiting readers' power to appraise the strengths and weaknesses of those reviews.[v]

Even though systematic review and meta-assay are considered the best evidence for getting a definitive answer to a inquiry question, there are certain inherent flaws associated with it, such as the location and selection of studies, heterogeneity, loss of data on important outcomes, inappropriate subgroup analyses, disharmonize with new experimental data, and duplication of publication.

Publication Bias

Publication bias results in it being easier to notice studies with a "positive" result.[19] This occurs specially due to inappropriate sifting of the studies where in that location is ever a trend towards the studies with positive (pregnant) outcomes. This consequence occurs more than normally in systematic reviews/meta-assay which need to be eliminated.

The quality of reporting of systematic reviews is still non optimal. In a recent review of 300 systematic reviews, few authors reported assessing possible publication bias even though at that place is overwhelming prove both for its being 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 have assessed or interpreted it appropriately.[20]

To overcome certain limitations mentioned in a higher place, the Cochrane reviews are currently reported in a format where at the stop of every review, findings are summarized in the author's point of view and also give an overall picture of the consequence past means of plainly language summary. This is constitute to be much helpful to sympathise the existing evidence about the topic more than easily past the reader.

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. A meta-analysis is a mathematical synthesis of the results of two or more principal studies that addressed the same hypothesis in the same way. Although meta-analysis can increment the precision of a event, it is important to ensure that the methods used for the reviews were valid and reliable.

High-quality systematic reviews and meta-analyses have dandy care to find all relevant studies, critically assess each report, 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 enquiry evidence, which is generally the all-time form of evidence, and hence positioned at the top of the hierarchy of evidence.

Systematic reviews can be very useful decision-making tools for primary care/family unit physicians. They objectively summarize large amounts of information, identifying gaps in medical inquiry, and identifying beneficial or harmful interventions which volition be useful for clinicians, researchers, and even for public and policymakers.

Footnotes

Source of Back up: Nil

Conflict of Interest: None declared.

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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3894019/

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