Systematic Reviews in Nursing Research

Systematic reviews

Dr Graeme D. Smith
Senior Lecturer
Nursing Studies
University of Edinburgh

MSc Advanced Nursing Practice
Research Methods

Systematic reviews

Reading:

Parahoo K (2006) Chapter 7: Literature reviews.
In:Nursing Research: principles, process and
issues pp134-144. Plagrave, New York.
Moore Z & Cowman S (2008) Chapter 10: the
Cochrane database and meta-analysis. In Watson
R et al. Nursing Research Methods. Churchill
Livingstone, Edinburgh

Reviewing literature

 Evidence base
 Literature review

 Systematic review

 Meta analysis

 PRISMA statement

Rigour in systematic reviews:
PRISMA statement
Evidence based medicine (practice):

‘Evidence based medicine (practice) is the
conscientious, explicit and judicious use of
current best evidence in making decisions
about care of individual patients’
Sackett (1996)

Ref: Sackett DL (1996) Evidence based medicine : what it is
and what it isn’t British Medical Journal 312: 71-2

PRISMA statement
 Evidence based health care
 Evidence based practice

 Evidence based nursing

What do we mean by best evidence?
 Studies/trials that use rigorous,
explicit, with reproducible methods

PRISMA statement
Five steps of evidence-based practice:
1. Formulate focused (clinical) question
2. Search the literature for evidence
3. Rate the quality of the available studies
4. Apply evidence to particular (clinical)
situation
5. Assess outcomes of decision
Guyatt et al 1992
Ref Guyatt GH et al (1992) Evidence-based Medicine Working
Group JAMA 268: 2420-2425

PRISMA statement

Why are systematic reviews important?

Searching and reviewing the literature
can tell you:
 if studies on the subject have been
done before
 what others have learned
 how practice has changed as a
consequence of the data
 problems experienced in researching
the subject
 who & where work has been done

PRISMA statement: Evidence

PRISMA statement
CATEGORIES OF EVIDENCE (BSG)
 Ia: Evidence obtained from meta-analysis of randomised

controlled trials.
 Ib: Evidence obtained from one randomised controlled trial
 IIa: Evidence obtained from at least one well designed
controlled study without randomisation
 IIb: Evidence obtained from at least one other type of well

designed quasi-experimental study
 III: Evidence obtained from well designed descriptive
studies: comparative studies and case studies
 IV: Evidence obtained from expert committee reports, or

opinions or clinical experience of respected authorities.

PRISMA statement
GRADING OF RECOMMENDATIONS (BSG)

 Recommendations are based on the level of evidence
presented in support and are graded accordingly
 Grade A requires at least one randomised controlled trial of
good quality addressing the topic of recommendation.
 Grade B requires the availability of clinical studies without
randomisation on the topic of recommendation
 Grade C requires evidence from category IV in the absence
of directly applicable clinical studies.

PRISMA statement
Failings in traditional reviews:
Inadequate & incomplete analysis of evidence
 Two land mark papers in 1990’s

 ‘Textbook reviews & narratives were woefully
inadequate in summarising knowledge’
Antman EM et al. (1992)
 ‘If original studies of effect of clot Tx after heart
attacks had been reviewed systematically
benefits of therapy would have been apparent in
mid-1970’s’ Lau J et al. (1992)

PRISMA statement
Failings in traditional reviews:
 Reviews always been part of health science

 Assessing effectiveness of interventions

 Synthesis of research is not always rigorous

 Historically reviewers rarely began with open
mind ‘dispassionate review hard to achieve’
 Build a case to support their own views

 Narrative studies are rarely explicit
selected/assessed

Literature reviews and nursing practice

 Nursing embraces challenge of conducting
systematic reviews
 Journal of Advanced Nursing:
over years 1990-2006
34 reviews published
1st appeared 1998
increasing trend…
 Requirement of high quality evidence in
nursing practice now more important than
ever
 Cochrane/JBI etc helps in this process

PRISMA statement
Definition of rigour:

‘use of demanding standards: the
application of precise and exacting
standards in the doing of something’

Encarta World English Dictionary

PRISMA statement
Literature Review vs. Systematic review
 What is the difference?

 Literature Review:

‘ is an examination of the literature from the
author’s perspective’

PRISMA statement
Literature Review vs. Systematic review
 What is the difference?

 Data from selected studies are combined and
compared
 If data can not be combined:
‘strength of evidence is assessed’
‘to evaluate the results’
 Conclusions are made on the basis of:
‘results found’ ‘presence
or absence of supporting evidence’

PRISMA statement
Systematic Reviews:
 Research is a big topic
 How do we access and use literature?

Common problems
 Finding the appropriate literature
 Making sense of contradictory findings
 Inadequate information
 Statistics ?
 Therefore – systematic reviews!

PRISMA statement
Definition of systematic review:
‘A systematic review is a review of a clearly
formulated question that uses systematic &
explicit methods to identify, select & critically
appraise relevant research & to collect & analyse
data from studies included in that review’
Cochrane 2005
Ref: Green et al (2005) Cochrane handbook for systematic
reviews of interventions
www.cochrane.org/resources/glossary.htm

PRISMA statement
Systematic reviews:
 Statistical methods (meta-analysis) may or may
not be used to analyse & summarise results of
included studies
Definition of meta-analysis:
‘use of statistical techniques in a systematic review
to integrate the results of included studies’
Cochrane 2005
Ref: Green et al (2005) Cochrane handbook for systematic
reviews of interventions
www.cochrane.org/resources/glossary.htm

Meta-analysis

Reference:

Ankem, K. (2005). Approaches to meta-
analysis: a guide for LIS researchers.
Library & Information Science
Research, 27(2), 164-176.
The Meta Analysis of Research Studies
http://www.edres.org/meta/

PRISMA statement
Useful website for systematic reviews:
Cochrane Collaboration
www.ich.ucl.ac.uk
NHS Centre for Reviews & Dissemination
www.york.ac.uk/inst/crd/welcome.htm
Centre for Evidence-based Medicine at Oxford
www.cebm.jr2.ox.ac.uk
Joanna Briggs Institute
www.joannabriggs.edu.au

PRISMA statement
Medline 3500 health care journals
EMBASE emphasis on European
literature
British Nursing Index British & other major
journals
CINAHL nursing, education & allied
professions
Pub-Med all major journals
projects in the NHS
SOCSCI education, psychology &
sociology

Personal experience of systematic reviews

Smith GD, Watson R, Thompson DR
(2008) Older people and
inflammatory bowel disease: a
systematic review. Journal of Nursing
and Healthcare of Chronic Illness 17
(11) 400-406.

IBD & Older people: a systematic review

 Objective: to review all published papers
comparing inflammatory bowel disease in
older and younger people.
 Design: systematic review.
 Search strategy: MEDLINE, CINAHL, EMBASE
and Cochrane databases were searched
1990 to 2005 inclusive.
 Keywords: systematic review, older people,
chronic illness, inflammatory bowel disease,
ulcerative colitis, Crohn’s disease




Search strategy:
 Papers were read by two independent
researchers (GDS & RW)
 selected if they compared younger
and older people with inflammatory
bowel disease
 excluded if they did not or were
concerned with other aspects of
gastroenterology


Results:
 seven papers fulfilled the selection criteria
 the clinical features of inflammatory bowel
disease are similar in younger and older
people as are indications for surgery,
survival and the usual wide spectrum of
severity of disease
 Corticosteroid treatment carries additional
risk for older people
 A gerontological and psychosocial
perspective was lacking from the papers
reviewed


Conclusion:
 The clinical features of inflammatory bowel
disease are similar in younger and older
people
 The possibility exists that quality of life and
adjustment in older people depend on age of
onset
 This has not been investigated
 Future lines of enquiry taking psychosocial
aspects of inflammatory bowel disease into
account in older people are explored.


Relevance to clinical practice:
 Nurses are playing an increasingly
important role in the assessment and
management of IBD patients
 Little is known about factors which could be
predicative of poorer HRQoL
 Poor understanding of the impact non-
intestinal manifestations upon HRQoL in IBD
in older people

Irritable bowel syndrome & HRQoL
Physical Psychosocial
Ab An
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Pa mina
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g mo lem
E ob
atin Pr
Blo

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Bo w Soc
Dis ial
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Dy Sexu
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IBS & hypnotherapy: a systematic review

Systematic review of GDH in IBS (2006)
 Nine electronic databases searched

 18 studies identified
four randomised controlled trials
two controlled trials
12 uncontrolled studies
 ALL indicate that GDH has some benefit

 ALL had methodological limitations

Wilson S et al (2006) The effectiveness of hypnotherapy in
the management of irritable bowel syndrome. Alimentary
Pharmacology & Therapeutics 24:769-780.

An update
Hot off the press:

Moher D, Liberati A, Tetzlaff J & Altman DG
(2009) Preferred reporting items for
systematic reviews and meta-analysis: the
PRISMA statement. British Medical
Journal: 339:2535-42.

An update
Systematic reviews increasingly important in
health care:
 Help keep health professionals up to date

 Starting point for clinical guidelines

 Justification for research funding

Swingler et al (2003)

Swingler GH, Volmink J & Ioannidis JP (2003) Number of
published systematic reviews and global burden of disease.
. British Medical Journal: 327: 1083-1084

An update
Value of systematic review depends
on:
 What was done?

 What was found?

 Clarity of reporting

Allow readers’ ability to assess the
strengths and weaknesses of review

An update
The PRISMA statement:
 27 item checklist

 Four phase flow diagram

It allows:
 Authors to improve reporting of systematic
reviews & meta-analysis
 Critical appraisal of published reviews

 Useful to scientific journals

PRISMA statement
History evaluation of quality of reviews
 1985-1986 study Mulrow (1987)
 50 review articles (meta-analysis)
 Four top medical journals
 None met explicit scientific criteria
 Led to formation of QUOROM
‘Quality of reporting of meta-analysis’

Ref: Mulrow CD (1987) The medical review article: The state
of the science. Ann Intern Med 106: 485-488

PRISMA statement
QUOROM:
 QUality Of Reporting Of Meta- analysis

 Focused on the reporting of meta-anlaysis
of RCT’s

Ref: Moher D et al (1994) Improving the quality of
reporting the meta-analysis of randomised
controlled trials: The QUOROM statement . Lancet
354: 1896-1900

PRISMA statement
PRISMA statement:
 27 item checklist

 Four phase flow diagram

 PRISMA aims to:
help authors improve reporting
help readers appraise reviews
 PRISMA is NOT:
‘a quality assessment instrument to
gauge the quality of a systematic review’

An update
From QUOROM to PRISMA:
 Differs in several respects

 PRISMA ‘decouples’ several items in
QUOROM checklist
 Checklist items are now linked
‘consistency across review reports’
 Flow diagram has been modified

An update
Flow diagram of information: PRISMA
 Identification

 Screening

 Eligibility

 Included

Checklist of items: PRISMA statement
 Title

 Abstract

 Introduction

 Methods

 Results

 Discussion

 Funding

Title:
 Identify the report as a systematic
analysis, meta-analysis or both

Abstract (structured summary):
 Background

 Objectives

 Data sources

 Study eligibility criteria

 Participants

 Interventions

Abstract (structured summary):
 Study appraisal/synthesis methods

 Results

 Limitations

 Conclusions

 Implications (clinical) of key findings

 Systematic review registration number

Introduction:
 Rationale

Description of the rationale for the review in
context of what is already known
 Objectives

Provide an explicit of questions being addressed
Importance of PICOS

PICOS ‘a taxonomy used in EBM’
 Participants

 Interventions

 Comparisons

 Outcomes

 Study design

PICOS
 Used commonly in EBM

 Help to find best evidence

 Help to formulate questions

 PICOS is NOT prescriptive

 Doesn’t tell someone how to do
intervention or comparison

Example of PICO:
 ↑ levels of obesity/diabetes in teenagers in area

 Examine levels obesity/diabetes in youth club

 Develop intervention to↓ obesity/diabetes

Population: youth club members
Intervention: improve food types at youth club
Comparison: food served before the intervention
Outcome: Are better foods served after study

PRISMA statement: Methods
 Protocol and  Data items
registration  Risk of bias in
 Eligibility criteria individual studies
 Information sources  Summary measures
 Search  Synthesis of results
 Study selection  Risk of bias across
 Data collection studies
process  Additional analysis

Eligibility criteria:
 Criteria for eligibility in review
‘rationale’ ‘justification’
 Specific study characteristics (PICOS)

 Report characteristics
years considered
language

Information sources:
 Description of all information sources
databases
dates of coverage
contact with study authors
additional ‘hand’ searches
 Date last searched

 Search
full electronic search strategy
search could be repeated
 Study selection
process for study selection
inclusion/ exclusion criteria

 Risk of bias in individual studies
description of method used
 Risk of bias across studies
affect cumulative evidence
i.e. publication bias
 Additional analysis
description of methods i.e.
meta-regression

PRISMA statement: Results
 Study selection
 Study characteristics

 Risk of bias within studies

 Results of individual studies

 Synthesis of results

 Risk of bias across studies

 Additional analysis

 Study selection
give number of studies screened
how were these screened?
accessed for eligibility?
number of studies in the review
reasons for exclusion
‘ideally a flow diagram’

 Study characteristics (for each study)
study size
PICOS
follow-up period etc.
 Risk of bias within studies (each study)
present data on risk of bias
? outcome level analysis

PRISMA statement: Results
Results of individual studies:
 Benefits and harm for all outcomes

 Simple summary data -intervention group

 Effect estimates & confidence intervals

Synthesis of results:
 Present results of each meta-analysis
include confidence intervals

Discussion:
 Summary of evidence

 Limitations

 Conclusions

Funding:
 Describe source of funding for systematic
review & other support

PRISMA statement: Discussion
Summary of evidence:
 Summary of main findings

 Strength of evidence for each
outcome
 Consider relevance to key groups
i.e. health care providers

Limitations:
 Limitations study & outcome level risk
of bias
 Limitations at review level
incomplete retrieval identified research
reporting bias
Conclusions:
 General interpretation of results

 Implications for future research

PRISMA statement: Caution
Systematic Reviews
Beware of:
 Reviews that cover too few studies:

 To few journals/databases

 Avoids ‘grey’ unpublished literature

 Selection suits author’s bias

Beware of:
 Review pays little attention to
‘quality’ of individual studies
included:
 No attempt made to sort strong from
weak
 Only identifies weakness in studies
contradictory to his / her position

Beware of (cont):
 Reviews that gloss over contradictory
findings
 The majority doesn’t always rule in research
 ‘Trust me, I am the expert’ reviews
 Weak description of how lit. was selected

= Reader unable to draw conclusions on
adequacy
 Inadequate descriptions of methodologies
used
= Reader not in position to draw their own
conclusion

Beware of (cont):
 Inadequate descriptions about differences…
in clients, programs, settings
 = Reader can’t interpret consistent findings
 Inadequate descriptions of actual statistical
results of reviewed studies
 = Reader can’t draw conclusions about
strength of effect in the study

Summary:
 Performing a systematic review is not easy

 Requires meticulous searching &
considerable attention to methodological
detail – before viewed as ‘systematic’
 Clear guidance: PRISMA
Chalmers I, Altman DG (1995) Systematic
Reviews. London: BMJ Publishing Group

An update

Thank you

Questions

Dr Graeme D. Smith
Graeme.Smith@ed.ac.uk

Systematic Reviews in Nursing Research

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