The Cochrane Collaboration and the Cochrane Oral Health Group

Anne Littlewood

Trials Search Co-ordinator

a.littlewood@manchester.ac.uk

The Cochrane Collaboration

• Established 1993 to respond to need for summaries of evidence in medicine and health

• 28,000 people involved from over 100 countries

• Cochrane Reviews are systematic reviews of primary research in human health care and health policy, and are internationally recognised as the highest standard in evidence-based health care.

• http://www.cochrane.org

The Cochrane Library

“Every day someone, somewhere searches The Cochrane Library every second, reads an abstract every two seconds and downloads a full-text article every three seconds."

The Cochrane Library usage data 2009

The 2010 impact factor for CDSR is 6.187, in the top ten of healthcare journals worldwide

http://www.thecochranelibrary.com

Cochrane Oral Health Group

• International network of healthcare professionals, researchers and consumers preparing, maintaining, and disseminating systematic reviews of randomised controlled trials in oral health.

• Oral health is broadly conceived to include the prevention, treatment and rehabilitation of oral, dental and craniofacial diseases and disorders.

Cochrane Oral Health Group

• 120 published reviews• 74 published protocols• 24 registered titles

• Oral Health Group’s impact factor = 3.600• Third biggest journal impact factor in Dentistry

after the Journal of Peridontology and the Journal of Dental Research

Challenges

• Maintain topic relevance and quality• Ensure infrastructure supports review process• Identify and reduce barriers to access• Encourage impact on practice• Update reviews• Global Alliance - invite international national and

specialist groups– Professional– Research

Benefits

• Membership of GA Board• Decision making to identify important reviews• Group member to content expert group• Recognition of funding

• Timely production of high quality important reviews• Consumer involvement• Enhanced products - podcasts, journal club

Experience to dateMember organizations to date:• British Orthodontic Society• British Society of Paediatric Dentistry • New York University Dental School

Currently in negotiations with:• Australian Society of Prosthodontics• US Dental Specialty Groups• International Association of Dental Research

Other national and international dental organizations have been approached

Cochrane Systematic Reviews

• Well structured research question is the place to start: PICO

• Once research question established, next stage is a systematic search of the literature

• Makes sure all relevant studies included• Reduces the risk of bias• Ensures that others can replicate study

PICOParticipants eg children with caries, smokers with periodontal disease

Intervention eg antibiotics, physiotherapy, powered toothbrushes

Comparison What the intervention is to be compared to: eg another intervention, placebo

Outcomes eg longevity of restorations, pain reduction, quality of life

Searching for Studies• Take the first two elements of the research question:

1. Participants2. Interventions

• List as many synonyms for each as you can

• Cochrane systematic reviews aim for MAXIMUM SENSITIVITY, to pick up ALL relevant RCTs

Which databases?

• MEDLINE• EMBASE• Cochrane Central Database of Controlled

Trials

• Other databases depending on topic:– CINAHL (Nursing)– PsycINFO (Psychology)

Constructing a Search Strategy

• Controlled vocabulary– MeSH and EMTREE– Hierarchy, broad concepts at the top, smaller

concepts lower down the “tree”

• Free text: words and phrases that can be found anywhere in the record

• Cochrane Systematic Reviews use a combination of both techniques

MeSH

• The National Library of Medicine in the US has developed an indexing system: Medical Subject Headings (MeSH)

• Subject headings are assigned according to the subject of an article by experienced indexers at the National Library of Medicine

• MeSH can be “exploded” to include all the terms that are included in that subject heading on the tree

How do I find the MeSH for my topic?

Go to: http://www.nlm.nih.gov/mesh/MBrowser.html

Free text searching

• Searching for MeSH terms limits the search to only include those terms in the keyword field of a record

• Free-text or keyword searching can be applied anywhere in the record – title, abstract, author, keywords or even full-text

• You can add a single word, or a phrase: for example: “dental caries”

Free text searching

• Most freetext searches in databases work using Boolean operators:– AND, OR, NOT– AND is used when the article must contain both

search terms– OR is used when a paper may contain either

search term– NOT is used when the search should retrieve the

first term and not the second

Free text searchingDatabases can support truncation or enable you to search

for the stem of a word e.g.

• PubMed:– child* will retrieve child, or children or child’s

• Some databases also support wildcard searches e.g.– wom?n will retrieve women or woman

• Symbol for truncation / wildcard can vary– * or $ or ? – Use the help pages of databases to check symbol

Example of a Cochrane SearchAlendronate for preventing periodontal disease in postmenopausal women#1 Alendronate [mh:noexp] #2 (Alendronate or biphosphonates or diphosphonates or clodronate or etidronate sodium or

etidronate acid or residronate or risedronate or incadronate or tiludronate or ibandronate or medronate or pamidronate)

#3 #1 or #2 #4 Menopause [mh:noexp]#5 (post-menopaus* or "post menopaus*" or postmenopaus*) #6 (menopaus* or “elderly women” or osteoporo*) #7 #4 or #5 or #6#8 Periodontal Disease [mh:exp]#9 periodont*#10 ("furcation defect*" or "alveolar bone loss" or "gingival recession" or (teeth and loss) or (teeth and

lost) or (teeth and lose) or (tooth and loss) or (tooth and lost) or (tooth and lose) or (tooth and mobil*) or (teeth and mobil*) or (tooth and extract*) or (dental and extract*) or (extract* and teeth))

#11 #8 or #9 or #10#12 #3 and #7 and #11

Exercise (20 mins)

Flossing for the prevention of dental caries• Participants: patients at risk of caries• Intervention: flossingConstruct a search: find the MeSH terms:http://www.nlm.nih.gov/mesh/MBrowser.htmlThink about what free text terms to add (synonyms

for caries)Test your search in PubMed:

http://www.ncbi.nlm.nih.gov/pubmed/