Cawood Systemic Review and Meta-analysis of the Effects of High

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

J Family Med Prim Intendance. 2013 Jan-Mar; 2(1): 9–xiv.

Systematic Reviews and Meta-analysis: Understanding the Best Show in Master Healthcare

S. Gopalakrishnan

Department of Customs Medicine, SRM Medical College, Infirmary and Research Centre, Kattankulathur, Tamil Nadu, Republic of india

P. Ganeshkumar

Department of Community Medicine, SRM Medical College, Infirmary and Research Centre, Kattankulathur, Tamil Nadu, Republic of india

Abstract

Healthcare decisions for private patients and for public health policies should be informed by the best available research evidence. The practice of evidence-based medicine is the integration of individual clinical expertise with the best available external clinical prove from systematic research and patient'due south values and expectations. Principal intendance physicians need evidence for both clinical practice and for public health determination making. The bear witness comes from good reviews which is a state-of-the-art synthesis of electric current evidence on a given research question. Given the explosion of medical literature, and the fact that time is always scarce, review articles play a vital role in decision making in evidence-based medical practice. Given that most clinicians and public health professionals do not take the time to runway down all the original articles, critically read them, and obtain the prove they need for their questions, systematic reviews and clinical practice guidelines may be their best source of prove. Systematic reviews aim to identify, evaluate, and summarize the findings of all relevant individual studies over a health-related outcome, thereby making the available evidence more accessible to decision makers. The objective of this article is to introduce the principal 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 understand a reliable review which will be helpful for their day-to-day clinical practice and inquiry activities.

Keywords: Prove-based medicine, meta-assay, primary care, systematic review

Introduction

Bear witness-based healthcare is the integration of all-time research testify with clinical expertise and patient values. Light-green denotes, "Using testify from reliable enquiry, to inform healthcare decisions, has the potential to ensure best practice and reduce variations in healthcare commitment." However, incorporating research into practice is fourth dimension consuming, and then we need methods of facilitating easy access to bear witness for busy clinicians.[i] Ganeshkumar et al. mentioned that most half of the individual practitioners in India were consulting more than 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 evidence available. However, to go along abreast with the continuously increasing number of publications in health 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 wellness 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 prove.[1,3,4]

Systematic reviews and meta-analyses take go increasingly important in healthcare settings. Clinicians read them to keep up-to-date with their field and they are often used as a starting point 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.[5]

This article is intended to provide an piece of cake guide to sympathise the concept of systematic reviews and meta-analysis, which has been prepared with the aim of capacity building for full general practitioners and other primary healthcare professionals in research methodology and twenty-four hour period-to-twenty-four hours clinical practice.

The purpose of this article is to introduce readers to:

1. The two approaches of evaluating all the bachelor testify on an issue i.e., systematic reviews and meta-analysis,

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-analysis, and

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

Application

What is the effect of antiviral treatment in dengue fever? Nearly often a primary care doctor needs to know convincing answers to questions similar this in a primary care setting.

To detect out the solutions or answers to a clinical question similar this, i has to refer textbooks, enquire a colleague, or search electronic database for reports of clinical trials. Doctors demand reliable information on such problems and on the effectiveness of big number of therapeutic interventions, simply the information sources are too many, i.e., nearly 20,000 journals publishing two million articles per twelvemonth with unclear or confusing results. Because no study, regardless of its type, should be interpreted in isolation, a systematic review is generally the all-time grade of evidence.[6] So, the preferred method is a good summary of research reports, i.e., systematic reviews and meta-analysis, which will give prove-based answers to clinical situations.

There are ii key categories of research: Primary research and secondary research. Chief research is collecting data directly from patients or population, while secondary research is the analysis of information already collected through primary research. A review is an commodity that summarizes a number of primary studies and may draw conclusions on the topic of interest which tin 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 assess, and synthesize on a specific outcome. It synthesizes the results of multiple master studies related to each other by using strategies that reduce biases and random errors.[7] To this cease, systematic reviews may or may non 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 often chosen overviews.

The evidence-based practitioner, David Sackett, defines the following terminologies.[three]

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

• Overview: When a review strives to comprehensively place and rail downward all the literature on a given topic (also chosen "systematic literature review").

• Meta-analysis: A specific statistical strategy for assembling the results of several studies into a unmarried estimate.

Systematic reviews adhere 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 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.[9]

Cochrane reviews

Cochrane reviews are systematic reviews undertaken by members of the Cochrane Collaboration which is an international not-for-profit arrangement that aims to assist people to brand well-informed decisions virtually healthcare by preparing, maintaining, and promoting the accessibility of systematic reviews of the effects of healthcare interventions.

Cochrane Chief Wellness Care Field is a systematic review of primary healthcare enquiry on prevention, treatment, rehabilitation, and diagnostic exam accuracy. The overall aim and mission of the Principal Health Care Field is to promote the quality, quantity, dissemination, accessibility, applicability, and impact of Cochrane systematic reviews relevant to people who work in primary care and to ensure proper representation in the interests of main intendance 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 inside the primary healthcare disciplines, as well every bit ensuring that primary care perspectives are adequately represented inside the Collaboration.[10]

Meta-assay

A meta-analysis is the combination of information from several independent primary studies that address the same question to produce a single estimate similar the effect of treatment or risk factor. It is the statistical analysis of a big collection of analysis and results from individual studies for the purpose of integrating the findings.[xi] The term meta-assay has been used to announce the full range of quantitative methods for research reviews.[12] Meta-analyses are studies of studies.[13] Meta-assay provides a logical framework to a research review where similar measures from comparable studies are listed systematically and the available outcome measures are combined wherever possible.[xiv]

The fundamental rationale of meta-assay is that it reduces the quantity of information by summarizing data from multiple resources and helps to program research equally well as to frame guidelines. It also helps to brand efficient utilise of existing data, ensuring generalizability, helping to check consistency of relationships, explaining data inconsistency, and quantifies the data. Information technology helps to improve the precision in estimating the adventure by using explicit methods.

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

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 almost 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 adequate intervention as a possible solution to the present healthcare demand of the customs. This step is most important since the remaining steps will exist based on this.

Reviewing the literature

This can be done by going through scientific resources such as electronic database, controlled clinical trials registers, other biomedical databases, non-English literatures, "gray literatures" (thesis, internal reports, non–peer-reviewed journals, pharmaceutical manufacture files), references listed in primary sources, raw data 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 demand to sift through the studies thus identified. The first sift is pre-screening, i.e., to decide which studies to think in full, and the second sift is selection which is to look over again at these studies and determine which are to be included in the review. The next step is selecting the eligible studies based on similar study designs, yr of publication, language, choice amidst multiple articles, sample size or follow-upward issues, similarity of exposure, and or treatment and completeness of information.

Information technology is necessary to ensure that the sifting includes all relevant studies like the unpublished studies (desk-bound drawer trouble), studies which came with negative conclusions or were published in non-English journals, and studies with pocket-sized sample size.

Appraise the quality of studies

The steps undertaken in evaluating the study quality are early on 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 assay.

For case, the quality of a randomized controlled trial can exist assessed by finding out the answers to the post-obit questions:

1. Was the assignment to the treatment groups really random?

2. Was the treatment allocation curtained?

3. Were the groups like 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 betoken estimates and measure out of variability presented for the principal outcome mensurate?

7. Did the analyses include intention-to-care for analysis?

Calculate the issue measures of each study and combine them

Nosotros need a standard measure of event which can be practical to each report on the basis of its result size. Based on their type of issue, following are the measures of upshot: Studies with binary outcomes (cured/not cured) have odds ratio, run a risk ratio; studies with continuous outcomes (blood pressure) accept means, divergence in means, standardized divergence in ways (effect sizes); and survival or time-to-upshot information accept hazard ratios.

Combining studies

Homogeneity of different studies can be estimated at a glance from a forest plot (explained below). For example, if the lower conviction interval of every trial is below the upper of all the others, i.e., the lines all overlap to some extent, and then the trials are homogeneous. If some lines do non overlap at all, these trials may be said to be heterogeneous.

The definitive test for assessing the heterogeneity of studies is a variant of Chi-square test (Mantel–Haenszel test). The final pace is computing the common estimate and its confidence interval with the original data or with the summary statistics from all the studies. The best estimate of treatment upshot 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 data to estimate the weighting.

Translate results: Graph

The results of a meta-analysis are usually presented as a graph chosen forest plot because the typical woods plots appear every bit forest of lines. It provides a unproblematic visual presentation of individual studies that went into the meta-analysis at a glance. It shows the variation betwixt the studies and an approximate of the overall result of all the studies together.

Forest plot

Meta-analysis graphs tin can principally exist divided into six columns [Figure i]. Individual study results are displayed in rows. The first column ("study") lists the individual study IDs included in the meta-analysis; usually the first author and twelvemonth are displayed. The 2nd column relates to the intervention groups and the third cavalcade to the control groups. The fourth column visually displays the study results. The line in the heart is called "the line of no effect." The weight (in %) in the 5th cavalcade indicates the weighting or influence of the written report on the overall results of the meta-assay of all included studies. The higher the percentage weight, the bigger the box, the more influence the report has on the overall results. The 6th column gives the numerical results for each study (e.g., odds ratio or relative risk and 95% conviction interval), which are identical to the graphical brandish in the fourth column. The diamond in the concluding row of the graph illustrates the overall result of the meta-analysis.[4]

Interpretation of meta-analysis[four]

Thus, the horizontal lines represent private studies. Length of line is the confidence interval (usually 95%), squares on the line represent issue size (take chances ratio) for the study, with area of the foursquare existence the study size (proportional to weight given) and position as betoken guess (relative gamble) of the study.[vii]

For case, the forest plot of the effectiveness of dexamethasone compared with placebo in preventing the recurrence of acute astringent 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 severe migraine headache in adults[17]

The overall effect is shown as diamond where the position toward the eye represents pooled bespeak gauge, the width represents estimated 95% conviction interval for all studies, and the black obviously line vertically in the centre of plot is the "line of no upshot" (due east.g., relative take chances = i).

Therefore, when examining the results of a systematic reviews/meta-assay, the following questions should be kept in mind:

1. Were apples combined with oranges?

   • Heterogeneity amidst studies may make any pooled judge meaningless.

2. Were all of the apples rotten?

   • The quality of a meta-analysis 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-assay.

4. Did the pile of apples corporeality to more just a hill of beans?

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

Subgroup assay and sensitivity analysis

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

Sensitivity analysis is used to make up one's mind how results of a systematic review/meta-analysis change by fiddling with data, for example, what is the implication if the exclusion criteria or excluded unpublished studies or weightings are assigned differently. Thus, subsequently the analysis, if changing makes little or no difference to the overall results, the reviewer's conclusions are robust. If the fundamental findings disappear, then 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, draw reliable and accurate conclusions, easily deliver required information to healthcare providers, researchers, and policymakers, help to reduce the time filibuster in the inquiry discoveries to implementation, ameliorate 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-analysis

As with all inquiry, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers' power to appraise the strengths and weaknesses of those reviews.[5]

Even though systematic review and meta-analysis are considered the best evidence for getting a definitive answer to a research question, at that place 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, conflict with new experimental data, and duplication of publication.

Publication Bias

Publication bias results in it existence easier to detect studies with a "positive" issue.[19] This occurs particularly due to inappropriate sifting of the studies where in that location is e'er a tendency towards the studies with positive (significant) outcomes. This effect occurs more than commonly in systematic reviews/meta-analysis which need to be eliminated.

The quality of reporting of systematic reviews is yet not optimal. In a recent review of 300 systematic reviews, few authors reported assessing possible publication bias even though there is overwhelming testify both for its beingness and its touch 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 accordingly.[xx]

To overcome certain limitations mentioned above, the Cochrane reviews are currently reported in a format where at the finish of every review, findings are summarized in the author's point of view and also requite an overall movie of the outcome by means of obviously language summary. This is establish to be much helpful to understand the existing evidence nearly the topic more easily past 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 according to explicit and reproducible methodology. A meta-analysis is a mathematical synthesis of the results of two or more than principal studies that addressed the aforementioned hypothesis in the same way. Although meta-analysis can increase the precision of a upshot, it is important to ensure that the methods used for the reviews were valid and reliable.

Loftier-quality systematic reviews and meta-analyses accept keen care to find all relevant studies, critically assess each study, synthesize the findings from individual studies in an unbiased fashion, and present balanced important summary of findings with due consideration of whatever flaws in the bear witness. Systematic review and meta-analysis is a manner of summarizing research evidence, which is generally the best form of show, and hence positioned at the elevation of the hierarchy of evidence.

Systematic reviews can exist very useful decision-making tools for master care/family physicians. 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.

Footnotes

Source of Back up: Nil

Disharmonize of Involvement: None declared.

References

ane. Light-green Southward. Systematic reviews and meta-analysis. Singapore Med J. 2005;46:270–iii. [PubMed] [Google Scholar]

2. Ganeshkumar P, Arun Kumar S, Rajoura OP. Evaluation of figurer usage in healthcare among individual practitioners of NCT Delhi. Stud Health Technol Inform. 2011;169:960–4. [PubMed] [Google Scholar]

3. Sackett D, Rosenberg WM, Gray JA, Haynes RB, Richardson WS. Evidence based medicine: What it is and what information technology isn't. BMJ. 1996;312:71–two. [PMC complimentary article] [PubMed] [Google Scholar]

4. Ried K. Interpreting and understanding meta-assay graphs--a applied guide. Aust Fam Md. 2006;35:635–8. [PubMed] [Google Scholar]

5. Moher D, Liberati A, Tetzlaff J, Altman DG PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. PLoS Med. 2009;six:e1000097. [PMC complimentary article] [PubMed] [Google Scholar]

seven. Melt DJ, Mulrow CD, Haynes RB. Systematic reviews: Synthesis of all-time testify for clinical decisions. Ann Intern Med. 1997;126:376–80. [PubMed] [Google Scholar]

eight. Clarke Thou. The cochrane collaboration and systematic reviews. Br J Surg. 2007;94:391–2. [PubMed] [Google Scholar]

9. Published by CRD, University of York; 2009. Jan, Systematic Reviews: CRD's guidance for undertaking reviews in health care. Centre for Reviews and Dissemination, University of York, 2008. [Google Scholar]

10. Cochrane Primary Wellness Intendance Field, The Cochrane Library, The Cochrane Collaboration, 23^rd Mar. 2012. [Final accessed on 2012 April 30]. Available from: http://world wide web.cochraneprimarycare.org/welcome .

eleven. Glass GV. Primary, secondary, and meta-assay of research. Educ Res. 1976;five:3–eight. [Google Scholar]

12. Goldman L, Feinstein AR. Anticoagulants and myocardial infarction. The bug of pooling, drowning, and floating. Ann Intern Med. 1979;90:92–4. [PubMed] [Google Scholar]

13. Kassirer JP. Clinical trials and meta-analysis. What practice they do for us? Due north Engl J Med. 1992;327:273–4. [PubMed] [Google Scholar]

14. Kavale KA, Glass GV. Meta-analysis and the integration of research in special pedagogy. J Learn Disabil. 1981;xiv:531–8. [PubMed] [Google Scholar]

xv. An introduction to meta-analysis, Cochrane Collaboration open learning textile for reviewers, Version 1.one, Nov. 2002. [Last accessed on 2013 Jan xv]. Available from: http://world wide web.cochrane-net.org/openlearning/html/mod3-two.htm .

sixteen. Higgins JP, Green S. Cochrane Handbook for Systematic Reviews of Interventions Version five.0.2. The Cochrane Collaboration. 2009. [Last accessed on 2009 Sep]. Available from: http://world wide web.cochrane-handbook.org .

18. Greenhalgh T. Papers that summarise other papers (systematic reviews and meta-analyses) BMJ. 1997;315:672–5. [PMC free article] [PubMed] [Google Scholar]

---

Manufactures from Periodical of Family Medicine and Primary Care are provided hither courtesy of Wolters Kluwer -- Medknow Publications

---

sharwooddosever76.blogspot.com

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

Share this post