Danny Liew's Lectures Flashcards
How many questions are addressed in a Cochrane review
1!
Why do a meta analysis?
Increase power
Resolve uncertainty
Improve estimates of effect size
Answer other questions
What are the PICOT components?
Population
Intervention
Comparator
Outcome
Time
What must you do when selecting studies for a meta-analysis?
Set inclusion and exclusion criteria to guarantee objectivity
What are three key statistical issue in a meta analysis?
Outcome
Weighting
Heterogeneity
What indicates the weight of an individual study in a forest plot?
Size of the box
What is the difference between a screening test and a diagnostic test?
Screening tests are for people who may have the disease (clinical suspicion) while diagnostic tests are for those who probably have the disease (no clinical suspicion)
What is the sensitivity? How do you calculated it?
of all people who have the disease - what proportion will the test pick up as positive.
TP/(FN+TP)
What is specificity?
The percentage of truely negative people that test negative
TN/(TN + FP)
What is the positive predictive value? How do you calculate it?
It is the percentage of positive tests that are truely positive.
TP/(TP+FP)
What is the negative predictive value? How do you calculate it?
It is the percentage of negative results that are truely negative.
TN/(TN+FN)
True/False, Sensitivity and specificity are constant for a given test
True
True/False, positive predictive value and negative predictive value are constant for a given test
False, they are depend on sensitivity and specificity AND the underlying prevalence of disease
Who should screening tests be aimed at?
At risk groups - eg Mammography for >50 y.o. women
What is a Receiver Operator Characteristic (ROC) curve?
It is a graphical representation of the trade between sensitivity and specificity in tests
