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Systematic (Literature) Review

Dr. Khalid Mahmood

ProfessorDepartment of Information Management

University of the Punjab

Professor of Information Management at University of the Punjab

Post-doctoral research fellow at University of California, Loss Angeles, USA

150+ publications Supervised many doctoral, M.Phil. and master theses Worked for various research journals as editor, reviewer and

editorial board member Conducted many trainings on research writing and publishing

About me

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Acknowledgment I have prepared this presentation with the help of

many books, presentations and Websites. I pay my sincere gratitude to all authors,

professors and experts for their efforts and contributions.

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Literature review The general term for all attempts to

synthesize the results and conclusions of two or more publications on a given topic. A review may or may not be systematic.

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Narrative review Traditional expert review; usually subjective in nature

Systematic review A review of a clearly formulated question that uses systematic

and explicit methods to identify, select and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review

Meta-analysis Quantitative evidence Use of statistical methods to combine the results of various

independent, similar studies More precise calculation of one estimate of treatment effect than

could be achieved by any of the individual, contributing studies

Levels of literature review

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Systematic review – history

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Astronomers claim to be the first users of this method

Explosion of SRs in health sciences in mid 1980s

Term “systematic review” was coined by health care researchers

SR became a significant tool for “evidence-based medicine” or “evidence-based practice”

Growth of SRs in health sciences

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SR – another definitionA systematic review “attempts to collate all empirical evidence that fits pre-

specified eligibility criteria in order to answer a specific research question.

It uses explicit, systematic methods that are

selected with a view to minimizing bias, thus providing more reliable findings from

which conclusions can be drawn and decisions made.”

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SR vs. narrative review

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Characteristics of an SR Clearly stated set of objectives with pre-defined

eligibility criteria for studies Explicit, reproducible methodology Systematic search that attempts to identify all

studies that would meet the eligibility criteria Assessment of the validity of the findings of the

included studies Systematic presentation, and synthesis, of the

characteristics and findings of the included studies

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Steps in an SR Build a review team Develop a protocol or plan Formulate review question Define inclusion and exclusion criteria Locate studies Select studies Assess study quality Extract data Analysis/summary and synthesis of relevant studies Present results Interpret results/determining the applicability of results

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Review team Normally a team work Key skills:

Managing research projects Leading, coordinating

Expertise in the topic Methodological expertise

Planning, searching, managing information, coding, analyzing, synthesizing, writing

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Protocol What is the title? What is the context and what are the conceptual

issues? What is the aim? What is the research question? What is the search strategy? What are the inclusion / exclusion criteria? How will the data be extracted and analyzed? How will the quality of studies be assessed?

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PICO – question components in medicine P – Population

Patients (Demographic factors, socioeconomic factors, setting, etc.)

I – Intervention Drug, procedure, etc.

C – Comparison Alternative to compare with intervention (placebo or

active) O – Outcome

Improvement, effect, measure, etc.

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PICO – example

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Sample questions In undergraduate medical education, does the

use of clicker technology in the classroom improve learning outcomes?

Are antiseptic washes more effective than non antiseptic washes at preventing nosocomial infections in patients undergoing surgery?

Are mass media (or school-based or community-based) interventions effective in preventing smoking in young people?

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Inclusion and exclusion criteria – example

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Searching literature Identifying major concepts Keywords, synonyms, controlled vocabulary Combination of concepts

Boolean operators, string, truncation, proximity, etc. Identifying where to search Search strategy

Varies in different databases Export citations to a reference management software

EndNote, etc. Documenting your search

Database name, date of searching, number of results

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Sources of literature Electronic databases

General vs. subject Grey literature

Conference proceedings, theses, reports, Websites

Browsing issues of topical journals Backward and forward citations of the most

relevant articles Conversation with experts in the field

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Search strategy – example

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Search strategy – example

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Record keeping log – example

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Study selection An initial assessment that occurs following the search It addresses the question “should the paper be

retrieved?” It is essential to use two assessors in both the selection

and critical appraisal processes to limit the risk of error Select only those studies that address the review

question and that match the inclusion criteria Scan titles and abstracts If uncertain? - Retrieve - scan full text

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PRISMA flow diagram

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PRISMA diagram – example

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Study quality assessment Choose appropriate checklist

related to study design It is better to use more reviewers

Inter-reviewer reliability

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Quality assessment criteria

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Quality assessment results

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Data extraction Think about what data you need to extract

from included studies to answer the questions

Pilot a draft data extraction form

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Data extraction form

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Summary table of evidence

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Data synthesis Will results be pooled? How? How will differences between studies be

taken into account? Can subgroups of data be made? How will results be displayed?

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Best of luck for your research endeavors!