- Trisha Greenhalgh, senior lecturer (firstname.lastname@example.org)a
- a Unit for Evidence-Based Practice and Policy, Department of Primary Care and Population Sciences, University College London Medical School/Royal Free Hospital School of Medicine, Whittington Hospital, London N19 5NF
In 1928, in his introduction to Sceptical Essays, Bertrand Russell wrote: “The extent to which beliefs are based on evidence is very much less than believers suppose.” Medical beliefs, and the clinical practices that are based on them, are a case in point. Debate continues as to whether scientific evidence alone is sufficient to guide medical decision making, but few doctors would dispute that finding and understanding relevant research based evidence is increasingly necessary in clinical practice. This article is the first in a series that introduces the non-expert to searching the medical literature and assessing the value of medical articles.
The Medline database
Over 10 million medical articles exist on library shelves. About a third are indexed in the huge Medline database, compiled by the National Library of Medicine of the United States. The Medline database is exactly the same, whichever company is selling it, but the commands differ according to the software. Vendors of Medline online and on CD ROM include Ovid Technologies (ovid) and Silver Platter Information (WinSPIRS).
Articles can be traced in two ways: by any word listed on the database, including words in the title, abstract, authors' names, and the institution where the research was done; and by a restricted thesaurus of medical titles, known as medical subject heading (MeSH) terms.
To illustrate how Medline works, I have worked through some common problems in searching. The scenarios have been drawn up using ovid software.
Problem 1: You are trying to find a known paper
Solution: Search the database by field suffix (title, author, journal, institution, etc) or by textwords.
First, get into the part of the database which covers the approximate year of the paper's publication. If you are already in the main Medline menu, select “database” (Alt-B). If you know the approximate title of the paper and perhaps the journal where it was published, you …