Narrative Review & Meta-Analysis PDF

Narrative Review & Meta-Analysis - A Step by Step Guidance - Dr.med. Dr.Sc. dr. Yanto Sandy Tjang, SpBTKV(K), MBA, MPH, MSc, PhD, FACS, FACC, FETCS, FICS  What Is Literature  Books  Audio-visual material  Journals  CDs/DVDs  C...

Narrative Review & Meta-Analysis - A Step by Step Guidance - Dr.med. Dr.Sc. dr. Yanto Sandy Tjang, SpBTKV(K), MBA, MPH, MSc, PhD, FACS, FACC, FETCS, FICS  What Is Literature  Books  Audio-visual material  Journals  CDs/DVDs  Conference papers  Electronic databases  Theses and  Government reports dissertations  Magazines  Bibliographies  Newspapers  Maps  Grey literature  Internet  Interviews and other  Indexes/Abstracts unpublished research Types of Literature Research Loop Types of Knowledge Synthesis Level of Evidence  Review of Literature  A body of text that aims to review the critical points of current knowledge on a particular topic  A comprehensive survey of publications in a specific field of study or related to a particular line of research  A summary of existing published literature made by experts who select and weigh findings available from the literature  A summary and interpretation of research findings reported in the literature  A process and documentation of the current relevant research literature regarding a particular topic or subject of interest  Review of Literature - Purposes  Define and limit problem  Develop familiarity with topic  Limit research to a subtopic within larger body of knowledge  Place study in historical perspective  Analysis of way in which study relates to existing knowledge  Avoid unintentional and unnecessary replication  Awareness of prior studies so as to avoid unneeded replication  Replication is reasonable if it is needed to verify prior results, investigate results that failed to be significant, or relate problem to a specific site  Select promising methods and measures  Knowledge of and insight into specific research designs for investigating a problem  Awareness of specific instruments, sampling procedures, and data analyses  Relate findings to previous knowledge and suggest future research needs  Relating prior research to what is known places current studyin perspective  This knowledge allows researcher to focus problem on what is not known  Develop research hypotheses  Suggestions for specific research hypotheses  Review of Literature - Designs Narrative Review  Selective review of the literature that broadly covers a specific topic  Does not follow strict systematic methods to locate and synthesize articles Systematic Review  Utilizes exacting search strategies to make certain that the maximum extent of relevant research has been considered  Original articles are methodologically appraised and synthesized Meta-Analysis  Quantitatively combines the results of studies that are the result of a systematic literature review  Capable of performing a statistical analysis of the pooled results of relevant studies Review of Literature - Designs (2) Narrative Review  Steps in Narrative Review  Identifying a topic 7. Write & present  Searching and finding Literature review 1. Identify topic literature  Evaluating literature 6. Syntesize 2. Search & find literature literature  Reading literature critically  Analyzing literature 5. Analyze  Synthesizing literature literature 3. Evaluate literature  Writing and presenting 4. Read Literature literature review critically  Searching and Finding Literature  Bibliographic information, abstract and full text  Formal and informal sources of literature  Print and online literature  Evaluating Literature  Evaluation for relevance  Index of a book, chapter or section headings, abstract of an article, introduction and conclusion, references or bibliography  Evaluation for reliability  Audience, authority, bias, currency, scope  Critical Reading  Passive vs active reading  Previewing  Reading  Taking notes  Responding critically  Analyzing Literature  Varying definitions of key terms  Methodology used  Enough evidence for claims?  Findings consistent with those of similar studies?  Synthesizing Literature  How does each reading relate to topic and purpose?  Define argument/thesis  Identify major trends or patterns emerging from the readings  Reassemble notes based on the results of readings, using organizational aids such as post-its, flags, etc.  Create a detailed topic outline  Synthesizing Literature (2)  Note on topic outline relationships among studies: which researchers, what page, etc. support each point?  Note consistency of results from study to study.  Note discrepancies among studies and provide possible explanations such as dates of studies, different methodologies.  Note landmark studies and if replicated.  Note how individual studies help illustrate or advance theoretical beliefs.  Note gaps or areas needing more research.  Make sure detailed outline follows a logical sequence of topics and subtopics. This will give the literature review the coherence it needs.  Writing and Presenting Literature Review  A general organization looks like a funnel  Broader topics  Subtopics  Studies like yours  How to Organize Studies  Chronological  By publication date  By trend  Thematic  A structure which considers different themes  Methodological  Focuses on the methods of the researcher, e.g., qualitative versus quantitative approaches  Making Links Between Studies Agreements  Similarly, author B points to…  Likewise, author C makes the case that…  Author D also makes this point…  Again, it is possible to see how author E agrees with author D… Disagreements  However, author B points to…  On the other hand, author C makes the case that…  Conversely, author D argues…  Nevertheless, what author E suggests…  Summary Table  It is useful to prepare.  Such a table provides a quick overview that allows the reviewer to make sense of a large mass of information.  The tables could include columns with headings such as:  Author  Type of study  Sample  Design  Data collection approach  Key findings  A Good Literature Review Is…  Focused - The topic should be narrow. It should only present ideas and only report on studies that are closely related to topic.  Concise - Ideas should be presented economically. Don’t take any more space than it needs to present the ideas.  Logical - The flow within and among paragraphs should be a smooth, logical progression from one idea to the next.  Developed - Don’t leave the story half told.  Integrative - The paper should stress how the ideas in the studies are related. Focus on the big picture. What commonality do all the studies share? How are some studies different than others? The paper should stress how all the studies reviewed contribute to the topic.  Current - The review should focus on work being done on the cutting edge of the topic. Meta-Analysis  History 1990s: Mid-1980s, explosion in methods popularity, 1977: first develop. Eg. esp. in modern Hedges, medical meta- Olkin, research 1904: analysis Hunter & quant. lit. published by Schmidt review by Smith & Pearson Glass (1977)  The Popularity of Meta-Analysis publications 3000 2500 2000 Number of Publications 1500 1000 500 0 93-94 94-95 95-96 96-97 97-98 98-99 99-00 2000-1 2001-2 2002-3 2003-4 Year of Publications Number of Meta Analysis publications are steadily increasing since 1993. We graphed the counts of journal articles included “meta analysis” as “publication type” from Pubmed, from years 1993 through 2004  Definition Quantitative approach for systematically combining results of previous research to arrive at conclusions about the body of research. – Quantitative: numbers – Systematically: methodological – Combining: putting together – Previous research: what's already done – Conclusions: new knowledge  Function of Meta-Analysis  Identifies heterogeneity  Increases statistical power and precision of the study  Develop ,refine, and tests hypothesis  Calculates sample size for future studies  Identifies data gaps  Reduces the subjectivity of study comparisons  Advantages of Meta-Analysis  Focuses attention on trials as an evaluation tool to increase the impact of trials on clinical practice.  Encourages designing of good trial and increases strength of conclusions.  Make the results fit for generalising to a larger population.  Improves precision and accuracy of estimates through use of more data sets.  May increase the statistical power to detect an effect.  Inconsistency of results across studies can be quantified, analyzed and corrected.  Hypothesis testing can be applied on summary estimates.  Moderators can be included to explain variation between studies.  The presence of publication bias can be investigated.  Disadvantages of Meta-Analysis  Meta-Analysis may discourage large definitive trials.  Increases tendency to unwittingly mix different trials and ignore differences.  Potential for tension between meta-analyst and conductors of original trials may introduce biasness.  Meta-Analysis of several small studies may not predict the results of a single large study.  Sources of bias are not controlled by the method.  A good meta-analysis of badly designed studies will still result in bad statistics.  How a Meta-Analysis Work  Individual studies – collecting similarity studies from previous research  Effect sizes – transform data (analysis results) into effect size reflect the magnitude of treatment effect or the strength of a relationship between two variables  Precision – The effect size for each study is bounded by as confidence interval, reflect the precision of effect size  Study weight – ideal studies (sample size are larger) are assigned relatively high weight  P-Value – a p-value for a test of the null hypothesis, if p