Seeking the Evidence : a protocol.

The following outlines the stages by which evidence can be accumulated for Evidence Based digests such as those found in Journal of Clinical Effectiveness.

Step 1 MEDLINE Search

N.B. MEDLINE is still the best starting point for EBM queries in general. For therapy questions, however, the Cochrane Library has edged ahead as it now contains more controlled trials than MEDLINE. We therefore suggest that you always try steps 1 and 2 in the protocol regardless of the particular search that you are conducting.

There are two alternative methods of filtering the evidence from MEDLINE:

  1. Conduct a search as usual and then limit the retrieval set to Review* in PT (for reviews); Clinical-Trial in PT (for clinical trials); /economics subheading or explode costs-and-cost-analysis (for economic studies); explode attitudes (for patient, staff or carer perspectives). [HOME]
  2. Use the PubMed version of MEDLINE (the Clinical queries interface). Select the type of question that you require (eg. diagnosis or therapy). Then indicate whether you wish to cast the methodological net wide (sensitivity) or to have a narrow focus (specificity).

    3.  

     
     
     

    If you retrieve little in the way of high quality evidence choose the most relevant looking reference and select "See Related Articles" PubMedDon't forget EMBASE, particularly for European Literature or articles on pharmaceuticals and CINAHL for the nursing literature and Consensus statements.

    A new approach involving PubMed searching in conjunction with other sources is the SUMSearch interface from the Society of General Internal Medicine.

    Step 2 Cochrane Library

    Potentially, all materials on the Cochrane Library can be included in the digest. Even review protocols can be referred to as research on the horizon. Eventual selection will depend on the volume of retrieved materials. Reviews will take precedence over trials providing they cover the question. Abstracts only of Cochrane reviews are available at: Cochrane Abstracts

    The Database of Abstracts of Reviews of Effectiveness [DARE] component of the Cochrane Library is searchable on the World Wide Web at: DARE Database

    Step 3 Best Evidence CD-ROM

    This covers critical appraisal summaries for ACP Journal Club and Evidence Based Medicine articles. If you don't have the CD-ROM you can access details of the articles via the IDEA, TRIP or DARE databases (see individual entries).
     
     

    Step 4 Healthstar & HTA sites

    This database of health technology assessment provides access to reports of health technology agencies from other countries and provides a grey-literature based complement to MEDLINE's more mainstream journal coverage:- HealthStar via Internet Grateful Med

     The NHS Centre for Reviews and Dissemination has recently placed an HTA Database of completed HTA reports on their Web site. The Catalogue of the New Zealand HTA is now searchable.

    International Network of Agencies for Health Technology Assessment (INAHTA) projects in progress are available at:Inahta Work in Progress

    At this point you may wish to try the two useful resources from the U.S. - Agency for Health Care Policy and Research and the Guide to Clinical Preventive Services via the HSTAT gateway. http://text.nlm.nih.gov/ftrs/gateway

    Step 5 NHS Economic Evaluation Database [NEED]

    The Centre for Reviews and Dissemination's specialist database of economic materials of relevance to the NHS:- NEED Database

    Step 6 TRIP Database

    This new database indexes 18 databases of evidence based information and provides links to pages on the Internet where appropriate:- TRIP Database

    Step 7 Internet Database of Evidence Based Abstracts and Articles (IDEA)

    Similar to TRIP in its coverage this resource indexes evidence based resources under their principal MeSH terms and provides pointers to sources such as individual artiles from Bandolier, AHCPR Guidelines, South and West DEC Reports etcetera. It also provides access to critically appraised topics from evidence based journal clubs e.g. Journal of Family Practice:- IDEA Topics List

    Step 8 Cliniweb, Omni & MDChoice

    These World Wide Web Resources provide broad coverage of health-related topics but endeavour to identify higher quality materials. Cliniweb is organised by MeSH heading: CliniWeb

    and MDChoice is organised by the Unified Medical Language System:-

    MDChoice

    OMNI, which has a British emphasis, uses subject indexing and includes brief descriptive abstracts of each resource:

     Organized Medical Networked Information [OMNI]
     
     

    Step 9 Lists of topics covered by Evidence Based Information Units

    Chances are that if you've been asked for a topic some other information professional may have been asked for it too. Three organisations that record their own evidence seeking strategies are the Aggressive Research Intelligence Unit (ARIF): ARIF Requests

    and the New Zealand-based Health Technology Assessment Clearing House: NZ HTA Requests

    Step 10 UK Academic Institutions, Government & quasi-government reports

    This strategy involves checking the Web-based publications lists for major evidence producers such as the Health Care Evaluation Unit (Bristol), Health Economics Research Unit (Aberdeen), Centre for Health Economics (York) etcetera as well as the Health Needs Assessment Reports produced by Raftery & Stevens and the work of the Trent Working Group on Acute Purchasing. Grey literature databases such as SIGLE and HMIC will prove invaluable. However on the World Wide Web you will probably want to check the following:

    Belinda ('Buckinghamshire Easy to Learn Local and National Database') is the database of the Buckinghamshire Health Authority Library. It holds references to circulars, books and reports held in the library: Belinda

    The Oxford Region Union Catalogue:

    Oxford Regional Catalogue

    or the North Thames Region Union Catalogue:

    North Thames Regional Catalogue

    The new Health Management Information Consortium (HMIC) database on CD- ROM (marketed by Silverplatter) has recently become the best one stop shop for U.K. Grey Literature. Enquire locally for availability.

    Where to next?

    Your topic may be covered by useful specialist databases that are available free of charge via the Internet. Some examples of these are contained in the ScHARR Guide Trawling the Net

     If you wish to pursue the evidence trail further you will need to target research registers for work in progress. The National Research Register issued under the NHS R&D Programme attempts to capture projects in progress. Other sources document the output of particular programmes (e.g. Medical Research Council or Economic and Social Research Council) or of academic institutions (e.g. Current Research In Britain). Enquire locally for availability.

     I am indebted to my colleague, Suzy Paisley, and to Julie Glanville at NHS Centre for Reviews and Dissemination for input and feedback to this protocol. Further suggestions are welcomed.

    Additional Reading

    Booth A. (1998) Following the evidence trail: EBHC on the Internet. He@lth Information on the Internet Feb 1 (1): 4-5.
    Booth A. (1998) Information about health technology assessment. Evidence based health policy and Management 2 (1):7-8.
    Glanville J. (1998) Where's the evidence? How to find clinical effectiveness information. Clinical Performance and Quality health care 6(1):44-48.
    Glanville J, Haines M & Auston I. (1998) Finding information on clinical effectiveness. BMJ 317: 200-203.