Segars Epidemiology

Question 1

What is incidence?

Answer 1

new cases of a disease

” water from faucet filling a bathtub”

Question 2

What is Prevalence?

Answer 2

old + new cases

“all the water in the bathtub”

Question 3

calculate incidence

Answer 3

# new cases of illness
divided by
# people at risk of illness

always subtract out those not at risk (already have illness or are immune)

Question 4

calculate prevalence (new + old cases)

Answer 4

total # cases 
divided by
# people in population

Question 5

calculate absolute risk reduction (ARR)

Answer 5

on test and see the word “absolute”, he wants us to subtract the placebo group% from the exposed/test group%

number of events (good or bad) in treated or control groups, divided by the number of people in that group

ie
group% - placebo group% = |x|

Question 6

calculate relative risk reduction (RRR)

Answer 6

(ARR) / R placebo/unexposed

Question 7

calculate number needed to treat (NNT)

Answer 7

1 / ARR in decimal format

ie 1/0.038 (38%) = 27 patients

Question 8

Calculate Risk Ratio

Answer 8

risk of outcome (exposed)/ risk of outcome (nonexposed)

Question 9

if ratio number is >1.0 then the event/outcome is what?

Answer 9

test answer should ay something like larger, biggger or more likely to occur in the comparison group

Question 10

if ratio is <1.0 then the event/outcome is what?

Answer 10

test answer should say something like less, lower, smaller, tinier

Question 11

interpreting ratios.

ie if RR = 1.53

Answer 11

study group has an increased 53% increased risk

Question 12

if RR = 8.2

Answer 12

study group is 8 time more likely to occur

anything larger than 2 we start saying blah blah blah times more likely

Question 13

if hazard ratio HR = 0.73

Answer 13

comparator numerator group has a 27% decreased chance of hazardous outcome

Question 14

When interpreting Ratios (RR/OR/HR) look for….
1- group comparison orientation (blah vs blah)

2-direction of words (increased, decreased)

3-magnitude 80% (1.8)/ 20% (0.8)

our class will be numerator. other classes denominator

Answer 14

asdsfqwesfdaDSF

Question 15

When looking for confidence interval (CI) both values are on the SAME SIDE of 1.0, it is always statistically……..

Answer 15

significant

Question 16

comparing any active drug to placebo, what goes in the top/bottom?

Answer 16

placebo goes to the bottom as denominator

drug gets to live in the numerator