Prognosis, critical appraisal, evidence based medicine,
n Assignment 1:
Read the reference article by Larpacis A et al.
User’s Guides to the medical literature V. How to use an article about prognosis, and try to understand the principles about prognosis.
n Assignment 2:
Read the article by H. Klar Yaggi et al.
Obstructive Sleep Apnea as a Risk Factor for Stroke and Death
Answer the following questions:
1. What is the study design?
2. a) What is the study population?
b) How did the author select the study population?
c) Is your case similar to the study population?
3. a) How is the OSA defined? (How is the exposure defined?)
b) Does the author provide a clear description of the stage of OSA?
4. Was follow up sufficiently long and complete?
a) How is the follow up period defined?
b) Any loss to follow up?
5. Was there adjustment for important prognostic factors?
6. a) What were the outcomes? Were objective and unbiased outcome criteria used?
b) How do they get the outcomes?
c) How were the outcomes ascertained?
7. What are the results?
a) Ex: What is the chance of a 60-year-old, obese, Caucasian male with OSA still alive in five years?
8. Potential biases
a) Are there any selection bias? Referral bias?
b) Can you see any potential for misclassification of exposure?
c) Can you see any potential for misclassification of outcome?
d) Are there any selective loss to follow up?
e) What factors did the author consider as potential confounders?
How was the problem of confounding handled?
n Assignment 3
You will be divided into four groups. And each group will work as a team and design a study about the prognosis of subclinical hyperthyroidism. We’ll have two groups presenting their designs and the two groups criticizing their work.
Before you design the study, you can search the literatures to get some ideas about subclinical hyperthyroidism. The study design has not to be perfect, just try to consider the principles questions in prognosis.
Each team needs to bring a computer to the classroom. During class, you’ll have some time to discuss your study, but it’s better to have an outline of your study design before you go to the class. And figure out who will present the study before class.
Consider the following questions:
1 What are the potential prognostic factors for subclinical hyperthyroidism?
2 What specific prognostic factor you want to study?
What study design you want to choose? Explain it.
3 Who will be your study population?
a) Your inclusion criteria and exclusion criteria.
b) How do you plan to select them? Hospital based or primary based?
4 What is your exposure ( definition)?
5 What outcomes do you want to measure? How do you plan to get them and have them ascertained?
6 How long is the follow-up period? What will you do to prevent loss to follow up?
7 What association measure do you plan to use? OR, RR, HR, Kaplan-Meier curve?
8 What potential confounders do you want to adjust?