Health Sciences Library

navigation bar Welcome Introduction Starting Your Search Using Key Resources UpToDate Cochrane ACP Journal Club PubMed Clinical Queries Quiz Resource Links References Evaluation

 

Searching the Medical Literature for the Best Evidence
Starting Your Search

Sample clinical scenario | Developing a searchable clinical question | Sample Clinical Question

Now that you know the basics about selecting an evidence-based literature source, let’s look at applying this to a specific clinical situation. We will then review searching for relevant information for this particular clinical scenario using our four key EBM resources, looking for both background and foreground information.

Sample clinical scenario

Consider the following clinical situation:

Amelia is a 72-year-old women who you are seeing in your office today for continuing problems with sharp, burning pain and extreme sensitivity to touch in her middle back. Six months ago you prescribed acyclovir for Amelia’s bout with shingles (herpes zoster). Her rash and blisters resolved within a month.

However, Amelia admits being under a lot of stress lately caring for her husband, who is in frail health. She has had trouble sleeping and her appetite is down. On exam today, Amelia exhibits allodynia and shows clear signs of postherpetic neuralgia. You know that tricyclic antidepressants have proven effective for many patients with this problem, but Amelia has some concerns about taking medications. You remember seeing some discussion of the use of two topical therapies, capsaicin and lidocaine patches, but are unsure of their efficacy and side effects.

Considering Amelia’s concerns, what do you recommend for relief of her pain?

Amelia

Amelia

Developing a searchable clinical question

The first step in gathering the best evidence is designing a searchable, focused clinical question using the PICO model. A question that uses the PICO format has four components: patient, intervention, comparison and outcome.

The next step is determining the category or type of clinical question you are trying to answer. Are you interested in therapy, diagnosis, prognosis, or etiology? Do you need to know more about prevention or screening? Each type of question requires looking for studies using different designs or methodologies.

When looking for the best information on therapies, for example, you should consider the hierarchy of research studies, also referred to as the evidence pyramid.

Evidence Pyramid
Source: SUNY Downstate Medical Center Evidence Based Medicine Course
http://library.downstate.edu/EBM2/2100.htm

Ideally, you would hope to find a systematic review of randomized, controlled trials. This type of review would offer an analysis of the highest quality therapeutic studies on your topic and provide recommendations for treatment. One very real limitation to keep in mind, however, is that this kind of rigorous review is often not available. This is due to both the complex nature of many health issues as well as the lack of scientific data on some therapeutic options.

Sample clinical question

Based on the PICO model just described, here is the focused question for our clinical scenario:

In an elderly woman with postherpetic neuralgia, are topical treatments as safe and effective as antidepressants in relieving pain?

Let’s assume you are starting off with limited knowledge of postherpetic neuralgia. Your first step is finding a summary to give you background information on this topic. We will now consider how to search UpToDate for this kind of overview. We will then look at resource options for foreground information to supplement your background knowledge by searching for systematic reviews and high quality research studies. For this, we will use the Cochrane Database of Systematic Reviews and the ACP Journal Club. Finally, we will see what additional foreground information is available by looking at the primary research literature, using the Clinical Queries feature in PubMed. The next sections of this tutorial will lead you step-by step through this process.

Top of Page

Searching the Medical Literature for the Best Evidence

© 2003 Health Sciences Library, UNC Chapel Hill