Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
18 Cards in this Set
- Front
- Back
|
How are the results of randomized trials expressed?
|
Efficacy= (rate in placebo - rate in treatment group) / (rate in placebo)
|
|
|
What is NNT?
|
# of patients who need to be treated to prevent 1 adverse outcome such as 1 death. NNT=1/ (Rate in untreated group) - (rate in treated group) or 1/attributable risk
|
|
|
What is a planned cross over trial?
|
1 group goes though a treatment for a time period then switches to a diff treatment. Ea person serves as there own control
|
|
|
What is a cohort study?
|
Compares incidence or death rates of exposed vs unexposed individ free of disease ***NON-RANDOMIZED
|
|
|
What are the 2 types of cohort studies?
|
Concurrent (prospective) & Retrospective (Historical)
|
|
|
Describe concurrent (prospective) cohort study.
|
Longitudinal study, PI identifies org study pop @ start study, follows patient through calendar time until disease does or doesn't develop. Disadvantage=needs long FU
|
|
|
Describe retrospective cohort.
|
Exposure &outcome defined from historical data w/ start date in the past. Disadvan=quality depends on the historical data
|
|
|
What is the measure of ass in cohort studies? Define.
|
Relative Risk (RR). RR= incidence in the exposed/ incidence in unexposed
|
|
|
How is Relative Risk interpreted?
|
RR=1 (no ass b/w E & D), RR>1 (+ ass; inc risk of D w/ E), RR<1 (- ass; dec risk of D w/ E or possible protective effect)
|
|
|
What are examples of cohort studies?
|
Framingham & MMR vaccine in autism
|
|
|
What is a case-control study?
|
Comparies exposure freq b/w persons w/ a specified illness or injury (cases) & others w/o (controls)
|
|
|
How do you measure ass in case-control studies?
|
Odds ratio (OR)- the ratio of the odds that the cases were exposed to the odd that the controls were exposed. OR=(odds that case was exposed)/(odds a control was exposed) or (ad/bc)
|
|
|
How is the odds ratio interpreted?
|
OR=1 (no ass), OR>1 (+ ass), OR<1 (- ass). Good estimate of relative risk if disease rare
|
|
|
What are the strengths of case-control studies?
|
Good for rare disease, can study multiple exposures, relatively small sample needed, less expensive, quicker
|
|
|
What are the weaknesses of a case-control study?
|
Can't measure incidence, specific to one disease, bad for rare exposure, diff to determine exposure, seletion of controls difficult, temporal seq of diseas-exp not clear
|
|
|
What is a meta-analysis?
|
Statistical analysis of a large collection of analysis results for individ studies for the purpose of integrating the findings
|
|
|
When are meta-analysis useful?
|
When studies are small & results not dramatic, results inconsistent b/w studies, can inc stat power, studies are RCT
|
|
|
What are the disadvan of meta-analysis?
|
Only includes published results, reviewed studies may vary considerably in quality, when RR & OR vary b/w studies meta-analysis may mask important diff, results may not always be reproducible
|
