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Introduction

MEDLINE (MEDlars onLINE) certainly is not the only medical bibliographic database. Other examples are EMBASE (a multi-lingual Europe oriented database relatively strong concerning "public health", medicine and chemistry) and BIOSIS (biochemistry, microbiology, neurologic sciences, biophysics).

MEDLINE, published since 1966 by the american National Library of Medicine (NLM) certainly is one of the most used databases, not in the least because it is focusing on the English literature (84% of the citations are English). MEDLINE includes the complete medical literature, including dentistry, psychology and veterinary sciences. Nevertheless, MEDLINE does not cover the complete literature, estimations range about 40%, however the most cited publications are included.

Access to MEDLINE is possible through different user friendly programs that are easy to use. A thorough knowledge markedly improves the quality of search sessions.

Preparing for a search

A successful search is only possible when you have a precise idea about what you are looking for. Therefore it is advisable to prepare a search session with paper and pencil, during the search session, these notes can be completed with with useful if not essential information about the searches you make.

Direct free text searching

Medline can be searched in different ways. A direct search in all available text is possible but will lack efficiency. A more effective approach will involve the thesaurus.
As an example we will investigate on the relationship between "mad cow disease" and the human disease called "Creutzfeldt-Jakob Disease".

First of all, we need to know the right professional nomenclature. It is important to find out that the veterinary scientific term for "mad cow disease" is "Bovine Spongiform Encephalopathy". A search based on the keywords "Mad Cow Disease" will lead to a few results (12, taking into account the MEDLINE databases from 1991 on), whereas "Bovine Spongiform" will lead to 408 references. This example clearly illustrates how badly chosen search keywords can lead to poor search efficiency. For complicated search terms, the exact spelling is of course vitally important. Wrong spelling such as in "Creutzfeld-Jakob" will still lead to results as authors too make mistakes (in this case 22 hits were found). The correct spelling will lead to 600 records however.

Also note that the word "disease" does not add any specificity, this word will appear so often in the database that it might even overload the search. An experienced user will take such considerations into account, before he actually performs a MEDLINE search on his computer or via the network.

Using the thesaurus

The thesaurus will help us optimize the search terms. Its purpose is th help you find the optimal combination of search keywords and their correct spelling. Preparing a search by a preceding thesaurus invocation will most probably improve the search efficiency.