Example of a Summary of Literature Review and Synthesis for Evidence-based Practice

• Periodical List
• J Family Med Prim Care
• five.two(1); Jan-Mar 2013
• PMC3894019

J Family Med Prim Care. 2013 Jan-Mar; ii(1): 9–14.

Systematic Reviews and Meta-analysis: Understanding the Best Testify in Principal Healthcare

S. Gopalakrishnan

Department of Community Medicine, SRM Medical College, Hospital and Enquiry Center, Kattankulathur, Tamil Nadu, India

P. Ganeshkumar

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

Abstruse

Healthcare decisions for individual patients and for public health policies should be informed past the best available enquiry 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's values and expectations. Primary care physicians need prove for both clinical practice and for public health conclusion making. The evidence comes from good reviews which is a state-of-the-art synthesis of electric current evidence on a given inquiry question. Given the explosion of medical literature, and the fact that fourth dimension is always deficient, review articles play a vital role in decision making in bear witness-based medical exercise. Given that nearly clinicians and public health professionals exercise non accept the time to track downwardly all the original articles, critically read them, and obtain the show they need for their questions, systematic reviews and clinical practice 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 available show more accessible to decision makers. The objective of this commodity is to introduce the principal care physicians about the concept of systematic reviews and meta-assay, 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 mean solar day-to-day clinical practise and inquiry activities.

Keywords: Evidence-based medicine, meta-analysis, primary intendance, systematic review

Introduction

Evidence-based healthcare is the integration of best inquiry evidence with clinical expertise and patient values. Light-green denotes, "Using testify from reliable research, to inform healthcare decisions, has the potential to ensure best practice and reduce variations in healthcare delivery." However, incorporating research into practice is time consuming, so we need methods of facilitating easy access to testify for decorated clinicians.[i] Ganeshkumar et al. mentioned that nearly half of the private practitioners in Republic of india were consulting more than iv h per solar day in a locality,[ii] which explains the difficulty of them in spending time in searching bear witness during consultation. Ideally, clinical decision making ought to be based on the latest evidence available. Still, to go on abreast with the continuously increasing number of publications in wellness research, a primary healthcare professional would need to read an insurmountable number of manufactures every day, covered in more than than 13 meg references and over 4800 biomedical and health journals in Medline solitary. With the view to address this challenge, the systematic review method was developed. Systematic reviews aim to inform and facilitate this procedure through research synthesis of multiple studies, enabling increased and efficient access to evidence.[1,3,iv]

Systematic reviews and meta-analyses have go increasingly of import in healthcare settings. Clinicians read them to go on up-to-date with their field and they are often used as a starting point for developing clinical do guidelines. Granting agencies may require a systematic review to ensure in that location is justification for further enquiry and some healthcare journals are moving in this direction.[five]

This commodity 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 chapters building for general practitioners and other main healthcare professionals in research methodology and twenty-four hour period-to-mean solar day clinical practice.

The purpose of this commodity is to introduce readers to:

1. The two approaches of evaluating all the available show on an effect i.east., systematic reviews and meta-analysis,

2. Discuss the steps in doing a systematic review,

3. Innovate the terms used in systematic reviews and meta-assay,

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? Most often a chief care physician needs to know convincing answers to questions like this in a master care setting.

To observe out the solutions or answers to a clinical question similar this, 1 has to refer textbooks, ask a colleague, or search electronic database for reports of clinical trials. Doctors need reliable data on such issues and on the effectiveness of large number of therapeutic interventions, simply the data sources are too many, i.eastward., nearly xx,000 journals publishing 2 million articles per year with unclear or disruptive results. Because no study, regardless of its type, should be interpreted in isolation, a systematic review is more often than not the all-time grade of prove.[6] So, the preferred method is a proficient summary of research reports, i.due east., systematic reviews and meta-assay, which will requite evidence-based answers to clinical situations.

At that place are two cardinal categories of research: Primary research and secondary research. Main research is collecting data directly from patients or population, while secondary research is the analysis of data already collected through primary research. A review is an commodity that summarizes a number of master studies and may describe conclusions on the topic of interest which tin can exist 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 outcome. Information technology synthesizes the results of multiple primary studies related to each other by using strategies that reduce biases and random errors.[7] To this end, systematic reviews may or may not include a statistical synthesis chosen meta-analysis, depending on whether the studies are similar enough so that combining their results is meaningful.[8] Systematic reviews are often called overviews.

The testify-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 rail down all the literature on a given topic (too called "systematic literature review").

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

Systematic reviews attach to a strict scientific design based on explicit, pre-specified, and reproducible methods. Considering of this, when carried out well, they provide reliable estimates about the furnishings of interventions so that conclusions are defensible. Systematic reviews can also demonstrate where noesis is lacking. This tin can then 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 (harm) furnishings, economical (cost) evaluations, and how and why interventions work.[9]

Cochrane reviews

Cochrane reviews are systematic reviews undertaken past members of the Cochrane Collaboration which is an international not-for-turn a profit arrangement that aims to assist 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 Intendance Field is a systematic review of primary healthcare research on prevention, treatment, rehabilitation, and diagnostic test accurateness. The overall aim and mission of the Main Wellness Care Field is to promote the quality, quantity, broadcasting, accessibility, applicability, and affect of Cochrane systematic reviews relevant to people who work in primary care 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 intendance perspectives are adequately represented inside the Collaboration.[ten]

Meta-analysis

A meta-analysis is the combination of data from several independent principal studies that accost the same question to produce a single gauge like the result of handling or chance gene. It 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.[thirteen] Meta-assay provides a logical framework to a research review where similar measures from comparable studies are listed systematically and the available effect measures are combined wherever possible.[fourteen]

The fundamental rationale of meta-analysis is that it reduces the quantity of information by summarizing data from multiple resource and helps to plan inquiry besides as to frame guidelines. It likewise helps to make efficient use of existing data, ensuring generalizability, helping to check consistency of relationships, explaining information inconsistency, and quantifies the information. It helps to better 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 testify, while the term "meta-analysis" volition refer to the statistical technique involved in extracting and combining information to produce a summary result.[fifteen]

Steps in doing systematic reviews/meta-analysis

Post-obit are the six key essential steps while doing systematic review and meta-assay.[16]

Define the question

This is the nearly important function of systematic reviews/meta-analysis. The research question for the systematic reviews may exist related to a major public wellness problem or a controversial clinical state of affairs which requires acceptable intervention as a possible solution to the nowadays healthcare need of the community. This step is most important since the remaining steps will be 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, "grayness literatures" (thesis, internal reports, non–peer-reviewed journals, pharmaceutical industry files), references listed in principal sources, raw data from published trials and other unpublished sources known to experts in the field. Among 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.eastward., to make up one's mind which studies to retrieve in full, and the second sift is selection which is to look again at these studies and decide which are to exist included in the review. The next step is selecting the eligible studies based on similar study designs, year of publication, linguistic communication, option amongst multiple manufactures, sample size or follow-up issues, similarity of exposure, and or handling and completeness of information.

It is necessary to ensure that the sifting includes all relevant studies like the unpublished studies (desk 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 good scoring system, developing a standard form for assessment, calculating quality for each study, and finally using this for sensitivity analysis.

For case, the quality of a randomized controlled trial can be assessed past finding out the answers to the following questions:

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

2. Was the treatment allocation concealed?

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 point estimates and measure of variability presented for the chief outcome mensurate?

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

Summate the outcome measures of each written report and combine them

We demand a standard measure of consequence which can be practical to each written report on the basis of its effect size. Based on their blazon of outcome, following are the measures of issue: Studies with binary outcomes (cured/not cured) have odds ratio, risk ratio; studies with continuous outcomes (blood pressure) accept ways, departure in means, standardized departure in ways (effect sizes); and survival or time-to-event data have run a risk 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.e., the lines all overlap to some extent, then the trials are homogeneous. If some lines practise non overlap at all, these trials may exist said to be heterogeneous.

The definitive test for assessing the heterogeneity of studies is a variant of Chi-foursquare examination (Mantel–Haenszel examination). The final step is calculating the common guess and its confidence interval with the original data or with the summary statistics from all the studies. The best gauge of treatment effect 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 gauge the weighting.

Interpret results: Graph

The results of a meta-analysis are usually presented as a graph called wood plot because the typical forest plots announced as forest 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 judge of the overall result of all the studies together.

Forest plot

Meta-analysis graphs tin principally exist divided into six columns [Figure 1]. Individual written report results are displayed in rows. The first column ("written report") lists the individual study IDs included in the meta-assay; ordinarily the first writer and year are displayed. The 2nd column relates to the intervention groups and the third cavalcade to the command groups. The fourth column visually displays the study results. The line in the middle is chosen "the line of no effect." The weight (in %) in the 5th column indicates the weighting or influence of the report 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 6th column gives the numerical results for each study (eastward.g., 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 effect of the meta-analysis.[4]

Interpretation of meta-analysis[4]

Thus, the horizontal lines represent individual studies. Length of line is the confidence interval (unremarkably 95%), squares on the line represent upshot size (risk ratio) for the study, with surface area of the square being the study size (proportional to weight given) and position every bit betoken approximate (relative risk) of the written report.[seven]

For example, 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 Effigy 2.[17]

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

The overall upshot is shown as diamond where the position toward the centre represents pooled point estimate, the width represents estimated 95% confidence interval for all studies, and the black plain line vertically in the middle of plot is the "line of no issue" (e.thousand., relative chance = 1).

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

1. Were apples combined with oranges?

   • Heterogeneity among studies may make any pooled estimate 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 tin can bias the findings of a meta-analysis.

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

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

Subgroup analysis and sensitivity analysis

Subgroup analysis looks at the results of unlike subgroups of trials, due east.g., by considering 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 be kept to a minimum.

Sensitivity analysis is used to decide how results of a systematic review/meta-analysis change past piffling with information, for instance, what is the implication if the exclusion criteria or excluded unpublished studies or weightings are assigned differently. Thus, after the analysis, if changing makes fiddling or no departure to the overall results, the reviewer's conclusions are robust. If the key findings disappear, and then the conclusions need to be expressed more cautiously.

Advantages of Systematic Reviews

Systematic reviews accept specific advantages because of using explicit methods which limit bias, depict reliable and accurate conclusions, easily evangelize required information to healthcare providers, researchers, and policymakers, help to reduce the fourth dimension delay in the research discoveries to implementation, ameliorate the generalizability and consistency of results, generation of new hypotheses well-nigh subgroups of the study population, and overall they increment precision of the results.[xviii]

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. 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-analysis are considered the best show for getting a definitive answer to a research question, there are sure inherent flaws associated with it, such as the location and choice of studies, heterogeneity, loss of information on important outcomes, inappropriate subgroup analyses, disharmonize with new experimental information, and duplication of publication.

Publication Bias

Publication bias results in it being easier to find studies with a "positive" outcome.[19] This occurs especially due to inappropriate sifting of the studies where there is always a tendency towards the studies with positive (significant) outcomes. This issue occurs more unremarkably in systematic reviews/meta-assay which need to exist eliminated.

The quality of reporting of systematic reviews is still non optimal. In a contempo review of 300 systematic reviews, few authors reported assessing possible publication bias even though there is overwhelming testify 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 have assessed or interpreted information technology appropriately.[20]

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 bespeak of view and also requite an overall picture of the outcome by means of manifestly linguistic communication summary. This is establish to exist much helpful to understand the existing evidence near the topic more hands past the reader.

Summary

A systematic review is an overview of master 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 ii or more master studies that addressed the aforementioned hypothesis in the same way. Although meta-assay can increment the precision of a result, information technology is of import 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 report, synthesize the findings from private studies in an unbiased mode, and present balanced important summary of findings with due consideration of any flaws in the prove. Systematic review and meta-analysis is a style of summarizing inquiry evidence, which is more often than not the best form of evidence, and hence positioned at the meridian of the hierarchy of prove.

Systematic reviews tin can be very useful determination-making tools for chief 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: Naught

Conflict of Involvement: None alleged.

References

1. Green S. Systematic reviews and meta-analysis. Singapore Med J. 2005;46:270–three. [PubMed] [Google Scholar]

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

three. Sackett D, Rosenberg WM, Grayness JA, Haynes RB, Richardson WS. Evidence based medicine: What it is and what it isn't. BMJ. 1996;312:71–two. [PMC free commodity] [PubMed] [Google Scholar]

4. Ried Chiliad. Interpreting and understanding meta-analysis graphs--a practical guide. Aust Fam Doctor. 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 free article] [PubMed] [Google Scholar]

vii. Cook DJ, Mulrow CD, Haynes RB. Systematic reviews: Synthesis of best bear witness for clinical decisions. Ann Intern Med. 1997;126:376–lxxx. [PubMed] [Google Scholar]

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

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

10. Cochrane Main Wellness Care Field, The Cochrane Library, The Cochrane Collaboration, 23^rd Mar. 2012. [Last accessed on 2012 Apr 30]. Available from: http://www.cochraneprimarycare.org/welcome .

xi. Glass GV. Primary, secondary, and meta-analysis of inquiry. Educ Res. 1976;5:3–8. [Google Scholar]

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

13. Kassirer JP. Clinical trials and meta-analysis. What practise they do for the states? N 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;14:531–8. [PubMed] [Google Scholar]

15. An introduction to meta-analysis, Cochrane Collaboration open learning textile for reviewers, Version 1.1, November. 2002. [Last accessed on 2013 Jan xv]. Available from: http://www.cochrane-net.org/openlearning/html/mod3-ii.htm .

16. Higgins JP, Greenish Due south. Cochrane Handbook for Systematic Reviews of Interventions Version 5.0.2. The Cochrane Collaboration. 2009. [Last accessed on 2009 Sep]. Bachelor from: http://www.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]

---

Articles from Journal of Family Medicine and Primary Care are provided here courtesy of Wolters Kluwer -- Medknow Publications

---

pattersonsocconeregal.blogspot.com

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

Share this post