The Lit Search
To guide our project, it was important to look at what was currently available in the literature to inform clinical decisions. I usually go through something like this when answering clinical questions.
I find it helps to break lit searches into four main pieces.
1) Ask a focused question
2) Search for the evidence
3) Appraise the evidence that you find
4) Apply to your patients
So you aren’t reading a four page blog at once, I’m going to break my discussions about these steps into more than one blog entry.
Ask a Focused Question
You may remember the pesky acronym PICO from pharmacy school or the most recent evidence based medicine workshop that you attended. PICO allows you to really focus on the question that you want to ask by forcing you to identify the Patient characteristics, Intervention of interest, Comparator or alternatives to the intervention and Outcomes that are relevant to the question that you are trying to answer. Our PICO question could be:
P - pediatric patients with osteosarcoma that receive methotrexate
I - concurrent beta-lactam antibiotic administration
C - no antibiotic or non beta-lactam antibiotic administration
O - clearance of methotrexate and occurrence of adverse effects of methotrexate (such as mucositis or renal toxicity)
Search the evidence
I usually start with tertiary sources, such as Lexi-Comp or UpToDate to get a general idea of what is out there. I tend to shy away from textbooks as they are usually limited by their publication year but they can sometimes be a good starting point if you are completely unfamiliar with an area. In general, I find tertiary sources allow me to gain a little more insight into the kind of things that I’m going to find in the primary literature and give some background information to build on.
I then dive into my databases or search engines (secondary sources) such as Ovid or Pubmed. This can sometimes be a daunting task if you search terms that are too general or complex and give back thousands of articles. I find that it helps to use simple terms and use AND/OR to combine terms and increase specificity or increase my search results respectively. Sometimes I end up doing multiple searches, using different terms or combinations of terms before I’m satisfied with the results that I’m seeing.
I use limits to refine my search results. Limits help to restrict your search results to a particular type of study or patient population. For example, if I’m looking for information about how a medication effects my usual patient population (pediatrics) I add an age limit to my search. Or you can limit your searches to randomized controlled trials or meta-analyses. I’ve been caught by articles that are in a different language so I sometimes add a limit to only find articles in English or French. Nothing is worse than thinking that you found a terrific article but it’s in a language that you have no chance of interpreting!
A couple of general articles that might help you with searches are:
- Lacasse M, Lafortune V, Bartlett L, Guimond J. Answering clinical questions, what is the best way to search the web. Canadian Family Physician. 2007; 53:1535-1536
- Corrall CJ et al. How to find evidence when you need it, part 1: databases, search programs and strategies. Annals of Emergency Medicine. 2002; 39:302-306.
If you have one available, an Evidence Based Medicine workshop also helps immensely to increase your comfort level and efficiency in doing literature searches. Tune in next time for my rant on appraisal of evidence and to find out what literature we found on our topic!