for dental post-graduates

1. Systematic Review
A Beginner’s Guide
Dr Saee Deshpande
MDS, Fellow-FAIMER, Fellow- Oral Implantology
Associate Professor
Dept of Prosthodontics, VSPM Dental College & Research Centre, Nagpur

2. Learning objectives
• Understand what is systematic review
• Understand the importance of systematic
review
• Learn the process of doing a systematic
review

3. In a nutshell….

5. Types of Research

6. Study Designs

7. How to identify study design?
Q1. What was the aim of the study?
• To simply describe a population (PO questions) descriptive
• To quantify the relationship between factors (PICO questions) analytic.
Q2. If analytic, was the intervention randomly allocated?
• Yes? RCT
• No? Observational study
• For observational study the main types will then depend on the timing of
the measurement of outcome, so our third question is:
Q3. When were the outcomes determined?
• Some time after the exposure or intervention?
cohort study (‘prospective study’)
• At the same time as the exposure or intervention?
cross sectional study or survey
• Before the exposure was determined?
case-control study (‘retrospective study’ based on recall of the exposure)

8. Situation Intervention Outcome
Traditionally……

9. All endodontically treated
teeth need post and core
and crowns
Never use cantilevers
Replace all teeth
Complete caries removal
Use of pit and fissure sealants
border molding, face bows
and split casts are must..!!
Antibiotic prophylaxis in PJR

11. Evidence Based Dentistry

12. • "A systematic review is 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" -- PRISMA
statement

14. Why needed?
• To practice evidence based dentistry for
better quality of patient care
• To reduce Research Wastage
• Stakeholders:
– Clinicians & caregivers
– Patients & their families
– Policy makers

15. The systematic review in context:
Source: HLWIKI International, copied under Creative Commons (CC BY-NC-SA 2.5 CA)

16. Narrative vs Systematic Review

17. Scoping vs Systematic Review

18. Types of a systematic review
1. Interventions
2. Methodology
3. Diagnostic test accuracy
4. Umbrella review/ overview of reviews

19. Examples

20. • Summary Review | Evidence-Based Dentistry volume19, pages116–117 (2018)
• Occlusal schemes for complete dentures. Pei Jia Loh & Colin Levey
• Data sources : Medline, Scopus and Cochrane Library databases
• Study selection: Randomised controlled trials (RCTs) or prospective studies comparing
bilateral balanced occlusion (BBO) with other schemes, eg lingual occlusion (LO) canine
guidance (CG) and neutral-centric or zero-degree (ZD).
• Data extraction and synthesis: One reviewer extracted the data and two reviewers
assessed risk of bias using the Newcastle-Ottawa scale for non-randomised studies and
the Cochrane risk of bias tool for RCTs. A narrative summary of the findings was
presented.
• Results : Seventeen studies, 11 RCTs and six prospective studies involving a total of 492
were included. Average follow-up period was 2.96 months (range 1-6 months). Six RCTs
were considered to be at low risk of bias, two at unclear risk and three at high risk.
Studies compared BBO with LO, CG and ZD. Twelve out of 16 studies reported on
quality of life and patients satisfaction.
• Conclusions: The present systematic review indicated that BBO does not confer better
quality of life/satisfaction or masticatory performance and muscle activity. Thus,
lingualised occlusion can be considered a predictable occlusal scheme for
complete dentures in terms of quality of life/satisfaction and Masticatory performance,
while canine guidance can be used to reduce muscular activity.

22. Mechanical properties of provisional dental materials: A systematic
review and meta-analysis PLoS One. 2018 Feb 28;13(2):e0193162.
Background: At present, there is no systematic review, which supports the clinicians’ criteria, in
the selection of a specific provisional material over another for a particular clinical situation. The
purpose of this systematic review and meta-analysis was to assess and compare the mechanical
properties of dimethacrylates and monomethacrylates used in fabricating direct provisional
restorations, in terms of flexural strength, fracture toughness and hardness. This review followed
the PRISMA guidelines.
Method: The searches were conducted in PubMed, Embase, Web of Science, Scopus, the New
York Academy of Medicine Grey Literature Report and were complemented by hand-searching,
with no limitation of time or language up to January 10, 2017. Studies that assess and compare
the mechanical properties of dimethacrylate- and monomethacrylate-based provisional restoration
materials were selected. A quality assessment of full-text articles were performed according to
modified ARRIVE and CONSORT criteria and modified Cochrane Collaboration’s tool for in
vitro studies.
Results: Initially, 256 articles were identified. After removing the duplicates and applying the
selection criteria, 24 articles were included in the qualitative synthesis and 7 were included in the
quantitative synthesis (meta-analysis).
Conclusion: It may be concluded that dimethacrylatebased provisional restorations presented
better mechanical behavior than monomethacrylate-based ones in terms of flexural strength and
hardness. Fracture toughness showed no significant differences. Within the monomethacrylate
group, polymethylmethacrylate showed greater flexural strength than polyethylmethacrylate.

23. Non restorative treatment of carious lesions on
primary teeth
American Dental Association: Centre for EBD

24. HOW IS IT DONE?
Systematic review……

25. • Step 1 - A clear and focused question.
• This may require preliminary searching to see what evidence is already available.
• Step 2 - Develop a protocol.
• This is your plan (or recipe) for your review.
– Search strategy and databases
– Eligibility criteria
– Screening process
– Critical appraisal process
– Data analysis / synthesis process
• Register your protocol with Prospero or publish it in a relevant journal.
• Step 3 - Conduct systematic searches.
• Step 4 - Screen search results for relevant studies that meet your eligibility criteria.
• Step 5 - Critically appraise the quality of the included studies.
• Step 6 - Extract relevant data from the included studies.
• Step 7 - Data synthesis.
• Step 8 - Summarise and interpret the evidence to answer your question.

26. PRISMA
Preferred Reporting Items for Systematic Review and Meta-Analysis
• PRISMA is an evidence-based minimum set of items for reporting
in systematic reviews and meta-analyses.
• PRISMA focuses on the reporting of reviews evaluating
randomized trials, but can also be used as a basis for reporting
systematic reviews of other types of research, particularly
evaluations of interventions.
• Several PRISMA extensions have been published in 2015 so far.
• PRISMA-P for developing review protocols was published in
January 2015 in Systematic Reviews and the BMJ.
• PRISMA-IPD (individual patient data) was published in JAMA in
April
• PRISMA-NMA (Network Meta-Analyses) was published in Annals
of Internal Medicine in June.

29. Other guidelines
• CONSORT Consolidated Standards Of Reporting Trials,
is a transparent and consistent procedure for reporting
trials.
• MOOSE Guidelines for Meta-Analyses and Systematic
Reviews of Observational Studies Meta-analysis of
observational studies in epidemiology.
• STROBE statement STrengthening the Reporting of
OBservational studies in Epidemiology.
• Modified ARRIVE (Animal research: reporting in in vivo
experiments)
• Modified CONSORT (for in vitro studies)

30. Formulating a research question
It is important you have a clear, well-formed,
focused question.
Benefits of doing this include:
• it makes searching for evidence easier
• you can easily apply the key concepts in your
question to your search.

32. The Protocol
• It is the plan or methodology of your
systematic review. You need to develop your
protocol at the beginning, before you start
your searches.
• You may refine your protocol as you progress
through your review.

33. What to include in your protocol
• Questions / aims of the review.
• Use your PICO breakdown (or the relevant
framework you are using).
• Your eligibility criteria (inclusion and exclusion).
• Where you will search (databases).
• How you will:
– screen your records.
– extract and manage the data.
– assess bias.
– analyse data.

34. Eligibility Criteria

35. Search
• How to search
• Where to search
• MeSH
• Report search results

36. Common tips
• It is best practice to search using both subject headings
and keyword searches.
• Always search one database at a time.
• Start your search in MEDLINE so you can use the
MeSH when mapping out your search.
• Always search one concept at a time.
• If you use a subject heading make sure you also run it
as a keyword search ('back up' subject headings with
keyword searches).
• You should not need to search for your outcome as
this is often implied in your results

37. What is MeSH?
• Medical Subject Headings (MeSH) is a controlled
vocabulary thesaurus of terms created by the
National Library of Medicine and used for
MEDLINE (PubMed) article records.
• They:
• give uniformity and consistency to the indexing
and cataloging of biomedical literature.
• are updated yearly and selected based on their
importance to clinical care and research.

38. Mapping your search

39. 1. Different terminology - physiotherapy or physical therapy
2. Different spellings - labour or labor
3. Singular and plural word forms - child or children; foot or feet;
sport or sports
4. Other word forms - diabetic or diabetes; obese or obesity
5. Generic vs specific - acetylsalicylic acid, aspirin, aspro clear
6. Common acronyms - cognitive behavior therapy or CBT
7. Words spelt with and without a dash - nonsurgical or non-surgical

40. Truncation
• Truncation - Most databases allow you to find word
variations by using a feature called truncation. Use a symbol
(often the *) to substitute for characters after a word stem.
• It is highly recommended you use truncation to include all
variations of a word in your search.
• diabet* finds diabetic, diabetes exercis* finds exercise,
exercises, exercising
• Limited truncation - allows you to specify how many letters
you want to find after a root word. This is only available in
some databases, for example MEDLINE, EMBASE and
PsycINFO.
• hospital$1 finds hospital or hospitals but NOT hospitalisation

41. Find different word spellings
• Wildcards - allow you to find different word
spellings.
• The wildcard symbol can vary in different
databases so always check the help screens.
• tumo?r finds tumor or tumour
• behavio?r finds behavior or behaviour
• urbani?ation finds urbanisation or urbanization

42. Phrase Searching
• It forces words together in one direction.
• Most databases require you put phrases in
double quotes, for example:
• "carpal tunnel syndrome" Most databases
require you to put your phrases in double
quotes. The one exception is Ovid databases
(for example: MEDLINE, EMBASE, PsycINFO)

43. Mining for keywords
• Some of the following tools may be useful to explore: PubMed
PubReMiner
• When you submit your query (which can be any query that can be
processed by PubMed), PubReMiner will process the result of that query
and display its results (in the form of selectable "keywords") in frequency
tables, which can be added/excluded from the query to optimize the
results.

44. Connectors
Understanding how to combine your terms using AND and OR is critical.
AND - connects different concepts to narrow your search
OR - connects similar concepts (synonyms) to broaden your search
NOT - removes terms. Avoid using NOT as it will likely remove relevant results

45. converting search terms into
search strategy

48. National Library of Medicine - Bethesda, MD, United States.
US Dept of Health & Human services:
The United States National Library of
Medicine (NLM) at the National Institutes of
Health maintains the database as part of the
Entrez system of information retrieval.

49. Some Concepts
• Both PubMed and PubMed
Central index millions of
biomedical articles. They
are provided by the
National Library of
Medicine and the National
Institute of Health.
• PubMed Central (PMC)
contains ALL full-text
articles and documents. It is
a subset of PubMed.
• MedlinePlus: for patients,
families and other
consumers

50. National Center for Biotechnology Information
• The NCBI houses a series of databases
relevant to biotechnology and biomedicine
and is an important resource for
bioinformatics tools and services.
• Major databases include GenBank for DNA
sequences and PubMed, a bibliographic
database for the biomedical literature. Other
databases include the NCBI Epigenomics
database.

52. Searching gray literature
• "...literature that is not formally published in
sources such as books or journal articles." This
can include information such as government
reports, conference proceedings, graduate
dissertations, unpublished clinical trials, and
much more.

53. Why search the gray literature if it
hasn't been peer-reviewed?
• There is a strong bias in scientific publishing
toward publishing studies that show some
sort of significant effect. Meanwhile, many
studies and trials that show no effect end up
going unpublished. But knowing that an
intervention had no effect is just as important
as knowing that it did have an effect when it
comes to making decisions for practice and
policy-making. Thus, the gray literature can
be critical.

54. • Identify and record the sources you will search, including some
indication of search terms used if appropriate.
• Try searching databases that specialize in gray
literature like OpenGrey.
• Conference proceedings: Identify professional organizations that have
conferences at which researchers might be presenting work related to
your topic. Search those conference proceedings on the organization's
website or by contacting organizational boards for access to past
proceedings that may not be online.
• Theses and dissertations: There are a number of databases dedicated
to theses and dissertations, which you can search using your search
terms.
• Identify government agencies, international and non-governmental
organizations, that might publish technical papers and reports on your
topic. Search their websites or any online libraries that they may
provide.
• Contact known researchers in the field to determine if there are any
ongoing or unpublished studies that s/he may be aware of.

55. A systematic search is an iterative
process.
• You will need to constantly evaluate, validate,
and verify your search results, as well as revise
and re-run your searches as required.
Your search strategy should be:
• comprehensive
• transparent
• replicable
• validated
• unbiased

56. Elements for peer review of electronic search strategies

57. Reporting your search

58. Record the following
• Title of database searched.
• Name of the database platform e.g. MEDLINE
(OvidSP).
• Database date range.
• Date search conducted.
• Years covered by the search.
• Complete search strategy (include all search
terms and limits).

60. Screen
• What is Screening?
• Screening is a two-part process in
which you determine whether
each individual article meets your
inclusion criteria, and therefore
should be included in your
review.
• To reduce bias, you should have a
minimum of two reviewers to
screen results (yourself and
someone else from your team).
• The Two Stages of Screening
• First Pass (Title/Abstract): This is
where you examine titles and
abstracts to remove obviously
irrelevant material. At this stage you
may not need to provide a
justification for your exclusions.
• Second Pass (Full Text): This is where
you examine the full text for
compliance with your eligibility
criteria. At this stage you must
provide reasons why you exclude
documents.

61. How do I screen?
• After you've finished creating
(building/developing) your search, save it as
the final version in each database that you
identified in your protocol. Once you have
them all ready to go, run each one and export
all of your results to Endnote, using a separate
group to store the results from each database.
From Endnote, export your references. Then
import to Covidence to commence screening.

63. Critical Appraisal
“Critical Appraisal Skills enable you to assess the
trustworthiness, relevance and results of published
papers so that you can decide if they are believable
and useful.” -- Critical appraisal skills, CASP (2013)
Methodological quality:
internal and external validity
Risk of bias

64. AMSTAR check-list
a measurement tool to assess the methodological quality of systematic
reviews.
MECIR
The Methodological Expectations of Cochrane Intervention
Reviews (MECIR) standards specify methodological expectations for
Cochrane Protocols, Reviews, and updates of reviews on the effects of
interventions.

65. Risk of bias assessment
Cochrane risk of bias assessment tool

66. Summary assessments of risk of bias for each important outcome

67. Example presentation of risk of bias assessments for studies in a Cochrane
review of therapeutic monitoring of antiretroviral drugs in people with HIV

68. Risk of bias assessment

69. Data Extraction
The information that you extract from the studies included in
your systematic review will depend on the purpose of your
review and your question.
• Only extract the data that is relevant to your particular
systematic review question.
• Develop a data extraction worksheet or workbook as part of
your protocol. This should include the key constructs you are
interested in as part of your review.
• Your worksheet or workbook should be comprehensive
enough that you should not have to go back to those studies.

70. Checklist of items - data extraction
• Source
• Study ID (created by review author).
• Report ID (created by review author).
• Review author ID (created by review
author).
• Citation and contact details.
• Eligibility
• Confirm eligibility for review.
• Reason for exclusion.
• Methods
• Study design.
• Total study duration.
• Sequence generation*.
• Allocation sequence concealment*.
• Blinding*.
• Other concerns about bias*.
• Participants
• Total number.
• Setting.
• Diagnostic criteria.
• Age.and Sex.
• Country.
• [Co-morbidity], [Socio-demographics], [Ethnicity].
• [Date of study].
• Interventions
• Total number of intervention groups.
• For each intervention and comparison group of
interest:
• Specific intervention.
• Intervention details (sufficient for replication, if
feasible).
• [Integrity of intervention].
Items without parentheses should normally be collected in all reviews; items in square brackets
may be relevant to some reviews and not others.

71. Data extraction Contd..
• Outcomes
• Outcomes and time points (i) collected; (ii)
reported*.
• For each outcome of interest:
• Outcome definition (with diagnostic criteria if
relevant).
• Unit of measurement (if relevant).
• For scales: upper and lower limits, and whether
high or low score is good.
• Results
• Number of participants allocated to each
intervention group.
• For each outcome of interest:
• Sample size.
• Missing participants*.
• Summary data for each intervention group (e.g.
2×2 table for dichotomous data; means and SDs
for continuous data).
• [Estimate of effect with confidence interval; P
value].
• [Subgroup analyses].
• Miscellaneous
• Funding source.
• Key conclusions of the study authors.
• Miscellaneous comments from the study
authors.
• References to other relevant studies.
• Correspondence required.
• Miscellaneous comments by the review
authors.
•

72. GRADE assessment of quality of evidence

73. Registering Protocol
• Registering your protocol helps avoid duplication of work. You do not
want anyone else to do the exact same review you are doing.
• Once you register your review will be available open access through their
database. It will have a unique registration number. This number can be
cited in publications and reports to provide the link between your planned
and completed review. This is recommended by PRISMA (2009) and many
publishers.
• These are international databases of prospectively registered systematic
reviews in health and social care. Key features from a review protocol are
recorded and maintained as a permanent record.
• The database is free to search and provides a comprehensive listing of
systematic reviews registered at inception to enable comparison of
reported review findings with what was planned in the protocol.
• Reviews should have health related outcome

74. Cochrane
• Archibald Leman Cochrane CBE (12 January 1909 – 18 June
1988) was a Scottish doctor noted for his book Effectiveness
and Efficiency: Random Reflections on Health Services.
• This book advocated the use of randomized control trials to
make medicine more effective and efficient.
• His advocacy of randomized controlled trials eventually led
to the development of the Cochrane Library database
of systematic reviews, the establishment of the UK
Cochrane Centre in Oxford and the international Cochrane
Collaboration.
• He is considered to be the originator of the idea of
evidence-based medicine in the current era.

75. • Cochrane, previously known as the Cochrane
Collaboration, was founded in 1993, is a British
charity formed to organize medical research findings
so as to facilitate evidence-based choices about health
interventions faced by health professionals, patients,
and policy makers.
• Cochrane includes 53 review groups that are based at
research institutions worldwide. Cochrane has
approximately 30,000 volunteer experts from around
the world.
• The group conducts systematic reviews of health-care
interventions and diagnostic tests and publishes them
in the Cochrane Library.
Cochrane

76. PROSPERO
• The International Prospective Register of
Systematic Reviews, better known
as PROSPERO, is an open access online database
of systematic review protocols on health-related
topics. Researchers can choose to have their
reviews prospectively registered with PROSPERO.
• The database is produced by the Centre for
Reviews and Dissemination at the University of
York in England, and it is funded by the National
Institute for Health Research.

77. Data set for a registry of systematic
reviews
• Research question, including:
– patients and population
– intervention or exposure
– comparison (if relevant)
– outcomes
• Search strategy and date of execution of search
• Criteria for inclusion and exclusion, including types of:
– Participants
– interventions or exposures
– Outcomes
– studies

78. Data set for a registry of systematic
reviews
• Methods used to assess risk of bias
• Method of analysis (including statistical
analysis if relevant)
• Anticipated start date
• Investigators
• Source of funding
• Competing interests of authors
• Date of registration

79. Review manager- RevMan
• Cochrane collaboration’s Software for
systematic reviews
• For all steps including protocol writing,
statistical analysis and editorial process.
• Free of cost

80. Archie
• Central database – stores all reviews
published and in progress along-with and
contact information
• Needs login : username and password

81. Cochrane Handbook

82. Funding systematic review
The NIHR Cochrane Programme Grant Scheme

83. Useful Resources

84. Now What…
• Topic
• In vivo
• In vitro
• Registration ??
• Desirable
• Preparation
• Read
• Decide your area of interest