Presentation and group activity for dietetic interns on critical appraisal of a randomized controlled trial. Uses the CASP checklists found here: http://www.casp-uk.net/casp-tools-checklists

1. Evidence Based
Nutrition Practice
CRITICAL APPRAISAL OF A RANDOMIZED CONTROLLED TRIAL

2. Agenda
Questions about critical appraisal, literature searching, PICO, etc.?
Critical appraisal of therapy articles: validity, results interpretation, application to patient
Tools for critical appraisal
In groups: critically appraise a nutrition therapy article

3. Apply
Appraise
Acquire
Ask Analyze
Patient
Five A's of EBP

4. What you want to know:
1. Are the results of the study valid?
2. What are the results?
3. Will the results help in caring for my patient?

5. EBM Pyramid – Study Designs
Each study design has different criteria to determine validity.
Critical Appraisal Checklists

6. Case Study (practice article #1)
Ms. MP is an 86 year old highly-functional resident of a nursing home who presents to the
emergency room after a fall in her home. Workup identifies a right femur fracture. The
orthopaedic surgeon recommends urgent repair and perioperative antibiotics. Ms. MP, who
with her husband operated a health food store for 40 years, has spent her life avoiding
medications and using natural remedies. Her husband mentions concern over the possibility of
diarrhea as a side effect of the antibiotics and asks if using fermented milk with lactobacillus
or some other probiotic product would prevent this side effect. Should she start taking a form
of probiotic to prevent this problem?
Q: In patients taking antibiotics, are probiotics helpful in preventing diarrhea?

7. What you want to know:
Article found after PubMed search:
Beausoleil M. 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. Can J Gastroenterol. 2007 Nov;21(11):732-6. PMID: 18026577
1. Are the results of the study valid?
2. What are the results?
3. Will the results help in caring for my patient?

8. Part 1: Are the results of the RCT valid?
Internal Validity: “Did the treatment cause the effect?” Determines a connection between the
independent and dependent variables.
How serious is the risk of bias?
Our job: Determine whether a weakness is serious enough to warrant reinterpretation of the
study’s results.

9. Part 1: Are the results of the RCT valid?
Factors to watch out for:
Randomization of patients
Group allocation concealed
After randomizing, are the groups similar?

10. In Groups:
Read the abstract, methods section, and table 1.
Answer checklist questions #1, 2, and 5.

11. Part 1: Are the results of the RCT valid?
Factors to watch out for:
Blinding of patients, researchers, and data collectors

12. Part 1: Are the results of the RCT valid?
Factors to watch out for:
“Intention to Treat”: patients analyzed in the groups in which they were first allocated
In order to minimize bias from patients dropping out of the study, they should be analyzed as
negative results in the group they were originally assigned.
Minimizes over estimation of treatment effect.
Complete Follow-up: All patients should be accounted for at the end.
◦ If all lost subjects had a bad outcome, what would be the study result?
Confused? Watch these videos.

13. In Groups:
Answer checklist questions #3, 4, and 6.
Hint: Look at Table 3 and Figure 1.

14. Part 2: What are the results?
1. How large was the treatment effect? (Consider: Is it clinically significant?)
(OR 0.34, 95% CI 0.125 to 0.944; P=0.05)
*Look at the Absolute Risk Reduction and NNT.*
Use tools to calculate these numbers!
What proportion of participants benefit from the intervention?
Patients needed to treat before a good outcome is expected
2. How precise was the estimate of the treatment effect (consider confidence intervals)?

15. Part 3: Will the results help locally?
In other words, “Can I apply the results of this study to my patient?”
This is where your clinical expertise comes in!
In groups:
Answer checklist questions #9, 10, and 11.
What would you do in this case study? Use probiotics or not?