Measures of association Flashcards


A. a total of 100 pateints…..
Interprete the raio of white to other

- compare
- direction
- magnitude
What is the Number Needed to Treat (NNT)?
- So how many patients need to be treated to reduce harm
-
1/ARR
- So if 1/.127 (12.7%) = 8 people need to be treated with drug to reduce 1 HSE
- Take the difference in Risks b/w 2 groups, and place that difference in decimal form in denominator BELOW value of 8
When you see absoulte think about _________. When you see relative think about ___________ .
Subtraction
Divison
What is incidence, risk, prevelence, and risk raitio?
why do we round up NNT/NNH?
because you cant treat half a person.
- What is counter factual theory?
- All else being equal and using the same group, what if the exposure didn’t occur
- Getting a group as close as possible to the tested group. one that is almost as similiar as it but maybe only has the tested variable thats nonexposed (is the only noticible change)
What are odds?
its s a ratio
Fruency of an exposure vs frequncy of not being exposed

What is an Odds Ratio? “OR”
Raito of the odds odds from two DIFFERENT groups
OR = odds of expoure (in HSE) / odds of exposure (in non HSE)

true or false: If the ratio b/w y and X is 1.98 : 1 , you would say that Y is 98% higher or more likely than X
TRUUUUUUUUUUUU

D.
Groupm comparison: Rampril (651) vs. placebo (826)
Direction: RR is given and is .078. It is less than 1 so REDUCED/DECREASED
magnitude: (1 - .78 ) * 100% = 22%
*placebo = always in denominator
Compared (in realtion) to …….. then denominator
Interprete the ratio of white to hispanic

- Compare
- directions
- magnitude
What does a 2x2 table look like?
Exposure/treatment
Disease
Outcome
Total
Yes
No
TOT
What is an odds and odds ratio? “OR”
oFREQUENCYof an outcome Occurringvs.NOT occurring
Frequency of Exposure vs.frequency of NOTbeing exposed


What is risk? (first define in your own words and then use a 2x2 table to elaborate)
- Probability of outcome of HSE in an individual group
- Exposed vs Non exposed
- Probability of Outcome in Exposed group: A/(A+B)
- Probability of outcome for NonExposed: C(C+D)
What is relative risk reduction (RRR)?
= (ARR / Risk unexposed)
” relatve reduction when recieving an RRR less than Risk (nonexposed)”
What is a forest plot used for?
It is a visual repersention of ratios. With an equalness line runing down the middle repersenting a 1:1 ratio

What is absolute difference?
Subtracting and taking then absolute value of that number
What happens to NNT value when difference between the groups increases?
NNT gets smaller.
Use (NNT/NNH)


Why do we now use relations like NNT/NNH?
Allows us to communicate effectively to our patients

A. 0.76

A
IF the comparison groups were switched so that it was placebo compared to ramprin would the numbers change?

yep
What is the best way to compare groups?
- To evaluate the SAME group with and without exposure. However, it’s finding a group that is similar as the exposed group as possible
- Assume that there exchangeable on all other factors than the tested one.
- Exchangeability = comparability
interprete the ratio of white to unknown

- Comparisons
- Direction
- magntude
What is attributle differences
not finsihed

What is Risk Ratio “relative Risk” “RR”?
RR = Exposed Risk of HSE
Non Exposed Risk of HSE
Intreprete the ratio of white to black.

- Comparisons
- direction
- magnitude
What is absolute risk reduction (ARR) ?
- How much “the Absolute” or “the certain” cause changes risk b/w exposed and non exposed groups
- It’s the same as Attributable Risk Reduction. However because of the counter factual theory we cant use the same exact group (because they have already been exposed) only one that is exchangeable.
- | Risk(exposed) – Risk (UnExposed) | = ARR
The absolute differences wll tend to be than relative difference
Smaller
What is Attributable Risk/Proportion “AR”
- The AR defines the Risk Difference of outcome attributed or probably causation to exposure difference b/w groups. The difference b/w the word “absolute” and “relative” is because our groups are exchangeable.
- | Riske(exposed) – Risk (UnExposed) | = A