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Steps to Searching of best evidence
There are several types of sources of medical research literature you might consider in your search for evidence:
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People (colleagues, attendings, and specialist consultants) - there are advantages and disadvantages with using 'people'. Firstly, they are convenient, easily accessible. Some of them could provide specific details about a specific problem, and they know the context in which you work. However, their knowledge may not be evidence-based, they are not always reachable, and they cannot give answer to every single question. |
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Text (traditional, on-line) - they are good in providing background information on certain topics. They do contain medical research but not the most updated because it takes a few years for the results to be reported in them. Therefore, textbooks are not a good place for up-to-date medical information and evidence. |
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Non-appraised or primary sources (individual research articles such as those you find on Medline) can help answer those very specific questions and provide the most recent data. However, Medline is very large, and may contain some irrelevant and non evidence-based references. Therefore, one must be able to search efficiently and critically appraise the information. Examples: Medline, BMJ, NEJM. |
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Pre-appraised or secondary sources, also known as "integrative literature" (critical appraisals of important individual studies or systematic reviews of multiple studies on a particular question). The appraisals are often written to maximize clinical utility. However, the databases of this are small and may not be able to provide answers to some very specific questions. Examples: Cochrane library, clinical evidence, best evidence. |
In an EBM search, you will consider pre-appraised or secondary sources of evidence first because it is more cost-effective and time saving. Pre-appraised sources include systematic reviews, evidence-based guidelines, collections of critical appraisals of research articles, evidence-based journals such as ACP (American College of Physicians) Journal Club, and textbooks such as Clinical Evidence published by the British Medical Journal.
There are several such information sources, including some that are free. The best are systematic reviews, including meta-analyses, because they combine information from several studies. The 'Cochrane Library' produces systematic reviews, and is your most reliable source.
It is very easy to use Cochrane! When it has the answer to your question, it is basically an effortless journey. However, if there is no match for your search, you can try other collections of pre-appraised evidence before using Medline. A list of such databases can be found in our EBM links.
However, many questions are not addressed in databases of pre-appraised literature, requiring you to turn to non-appraised, primary sources. The best database of original medical literature is still MEDLINE.
Medline is the electronic database maintained by the National Library of Medicine. It indexes articles dating from 1966. Not all medical literature is indexed in Medline (the European version of Medline is called embase), although many will argue that it contains the most important medical literature.
Many interfaces are available for searching Medline, some free and others proprietary. Different interfaces use different search protocols and may yield different results. Some (e.g., 'Ovid') may simultaneously search other databases.
"Pub Med" PubMed is free, and available to anyone from any computer that has internet access.
Medline contains information about so many thousands of articles, that if you just type in a keyword like you did in Cochrane, you're likely to get thousands of hits. That's far too many to be very helpful because you would then have to read through all those titles and abstracts to find the one or two articles that are directly relevant to your question.
In order to find good evidence-based articles effectively, you have to learn how to use
Medline wisely.
Other good EBM search engines |
