Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
The HSHSL is a part of the University of Maryland, Baltimore | My UMB The Elm UM Shuttle Blackboard
Library Logo

601 West Lombard Street
Baltimore MD 21201-1512

Reference: 410-706-7996
Circulation: 410-706-7928

Evidence-Based Practice Tutorial: Practicing Evidence-Based Medicine

Practice Scenario

Please read through the each of the steps below and make note of your answers to the practice questions. The answer key will be at the bottom of the page.

1. Assess the Patient

A clinical scenario presents itself during your work:

2. Asking a Clinical Question

Which of the following clinical questions is the most appropriate?

a. What is the best treatment for diarrhea?

b. In patients taking antibiotics, are probiotics helpful in preventing diarrhea?

c. Do probiotics prevent diarrhea in the elderly hospitalized patient?

3. Acquiring the Evidence

Which of the following PubMed search strategies best addresses the clinical question?

a. diarrhea AND best treatment; Limited to Free Full Text

b. diarrhea AND probiotics AND elderly AND female AND adult; Limited to English

c. antibiotics AND diarrhea AND probiotics; Limited to randomized control trial

4. Appraising the Evidence

Your search results included the following article. Please read the following article, particularly the methodology section:

Effect of a Fermented Milk Combining Lactobacillus Acidophilus Cl1285 and Lactobacillus Casei in the Prevention of Antibiotic-Associated Diarrhea: A Randomized, Double-Blind, Placebo-Controlled Trial

You are likely to find that the answers to the below validity questions may not always be clearly stated in the article and that you may have to use your own judgment about the importance and significance of each question.

a. Randomization: Were the patients randomized?

b. Concealed Allocation: Was group allocation concealed?

c. Baseline Characteristics: Were the patiend in the study groups similar with repect to known prognostic variables?

d. Blinding: To what extent was the study blinded?

e. Follow-Up: Was follow-up complete?

f. Intention to Treat: Were patients analyzed in the groups to which they were first allocated?

g. Equal Treatment: Aside from the experimental intervention, were the groups treated equally?

5. Applying the Results

Think about your patient, her goals, your treatment recommendation for her, the cost and adverse effects of probiotics, and help her decide whether to start taking probiotics.

6. Assessing the Outcome

Monitor your patient's progress to see if the intevention is successful. Share your results, positive or negative, with fellow physicians and other interested parties to reduce duplication of efforts and promote information sharing.

Answers to Practice Scenario

1. Ask the Question     

a. This is a backgroud question about treatments for diarrhea. It does not address the specific treatment being considered or the specific cause of the diarrhea.

b. Correct. This question is well focused - we know the patient problem (antibiotics and diarrhea), the specific intervention (probiotics) and the desired outcome (prevention/treatment) for this patient.

c. This is a vague question - elderly and hospitalized may not be as important as the specific cause of the problem.

2. Acquire the Evidence  

a. This search is too general and does not include the specific treatment or type of study. By limiting to Free Full Text, you may miss important articles that are available from your Medical Library.

b. This search may be too limiting. While it has the right problem and intervention, it limits the search by criteria that are not essential to the questions and does not limit to a study design.

c. Correct. This search strategy includes the specific patient problem (antibiotics AND diarrhea), the intervention (probiotics), and the right type of study (RCT) to provide good evidence.

3. Appraise the Evidence

a. Yes. It is reported that patients were randomized, but they do not give any details as to how randomization was carried out.

b. It is not clear. They do not report enough information to determine if the allocation was concealed.

c. Yes. Table 1 displays the characteristics at baseline. It should be noted that more patients in the placebo group were taking laxatives and more patients in the placebo group took beta-lactams during the study. You need to think about how this might affect the outcomes.

d. Patients were blinded. Both preparations were provided in identically labelled containers; their taste and texture were similar. While this is labelled as a double blind study, it is not clearly states as to who else was blinded.

e. Follow-up was complete. They had data for all patients in the study which lasted up to 21 days after the last administered does of antibiotics.

f. Yes. The study reported that the analyses of the primary and secondary outcomes were based on the intention-to-treat principle.

g. Yes. It appears the both groups were treated the same except for the intervention. All patients were followed in the same way and both groups allowed additional medications as required.