WISER: Sciences.

Doing a Systematic Review

Jo Hunter & Linda Atkinson

What is a Systematic Review?

“A scientific tool which can be used to summarise, appraise and communicate

the results and implications of otherwise unmanageable quantities of

research”

(NHS CRD, 1996)

Workshops in Information Skills and Electronic Resources

What is a Systematic Review?

• Systematic in identifying/evaluating

• Objective in interpretation

• Explicit in statement of objectives

• Reproducible in methodology

(Greenhalgh, 2000)

Workshops in Information Skills and Electronic Resources

What about “Meta-analysis”?

“A specific statistical technique used to combine the results of several studies

into a single estimate”

(Sackett et al., 1991)

Workshops in Information Skills and Electronic Resources

Systematic Review - Advantages

• Summarise information• Overcome bias inherent in small studies• Overcome lack of generalisability• Heterogeneity (inconsistency in results)

can be identified

Workshops in Information Skills and Electronic Resources

Which organisations produce systematic reviews?

• Cochrane Collaboration

• NHS Centre for Reviews and Dissemination

• Campbell Collaboration

Workshops in Information Skills and Electronic Resources

The Cochrane Collaboration

• Formed in 1993• International, with several Centres• Systematic reviews available via the

Cochrane Library

www.nelh.nhs.uk/cochrane.asp

Workshops in Information Skills and Electronic Resources

The NHS CRD

• Formed in 1994• Works with the UK Cochrane Centre• Produces guidance on writing

systematic reviews• Provides access to systematic reviews

www.york.ac.uk/inst/crd/index.htm

Workshops in Information Skills and Electronic Resources

The Campbell Collaboration

• Set up along similar lines to the Cochrane Collaboration

• Access to systematic reviews re: social and educational policies/practices

www.campbellcollaboration.org

Workshops in Information Skills and Electronic Resources

What’s the best methodology?

• Updated guidance from the NHS CRD www.york.ac.uk/inst/crd/report4.htm

• Up-to-date advice from the NHS CRD www.york.ac.uk/inst/crd/reviews.htm

• The Cochrane Handbook www.cochrane.org/resources/handbook

Workshops in Information Skills and Electronic Resources

Three Broad Stages

1. Planning – identify need, prepare proposal, develop protocol

2. Conducting – find, select, appraise, extract, synthesise literature

3. Reporting – write up and disseminate results

Workshops in Information Skills and Electronic Resources

Stage 1: Planning

• Is there a need?

• Find a team – Someone to obtain funding– Someone to do most of the work– An information specialist– A methodologist– A content expert– An advisory group

Workshops in Information Skills and Electronic Resources

Stage 1: Planning

• Draw up a protocol– Background & rationale– Study question(s)– Inclusion criteria– Details of literature search– Data extraction– Proposed analysis– Plans for reporting/dissemination

(Dinnes, 2000)

Workshops in Information Skills and Electronic Resources

Stage 2: Conducting the review

• Literature search - comprehensive• Select studies – use an eligibility form• Assess quality of selected studies – use

checklist• Data extraction – use forms/tables• Data synthesis – qualitative & quantitative

Workshops in Information Skills and Electronic Resources

Literature search

• Focus on reports from RCTs• Comprehensive – minimise selection bias• Electronic Databases – 100s exist• Search strategy – customise for each database• Handsearching – not all RCT reports are

included in databases, or difficult to find

Workshops in Information Skills and Electronic Resources

Search Strategy

• Comprehensiveness vs. precision• Iterative process• 3 sets of terms:

– the health condition of interest– the intervention evaluated– types of study design included (usually RCTs)

Workshops in Information Skills and Electronic Resources

Stage 3: Reporting & Dissemination

• Succinct and consistent report

• Publish in a professional journal

• Promote in conference presentations

www.nelh.nhs.uk/cochrane.asp

Workshops in Information Skills and Electronic Resources

SUMMING UP

Systematic Reviews:• Are time consuming• Need Planning• Must be documented at all stages• Need rigorously applied inclusion criteria• Need standardised critical appraisal

method• Need statistical expertise• Should include your methodology

Workshops in Information Skills and Electronic Resources

TOP TIPS

1. Make sure you learn how to use a reference management system such as Endnote/Reference Manager/Procite

2. Seek out your Local Subject Librarian for advice on resources and searching strategies

Workshops in Information Skills and Electronic Resources

Bibliography• Dinnes J. (2000). Protocols for systematic reviews.

Presentation at the Systematic Review Development Programme, Centre for Statistics in Medicine, Institute of Health Sciences, Oxford 11/09/00.

• Greenhalgh T. (2000). How to read a paper: the basics of evidence based medicine. (2nd edition). London: BMJ Publishing.

• Sackett D., Haynes RB., Guyatt GH. & Tugwell P. (1991). Clinical Epidemiology: A basic science for clinical medicine. 2nd edition. Little, Brown & Company.

Workshops in Information Skills and Electronic Resources

WISER: Sciences.Doing a systematic review

What did you think of this presentation?

www.oucs.ox.ac.uk/courses/feedback

Jo Hunter & Linda Atkinson Oxford University Health Care Libraries