MEASURES OF ASSOCIATION (RISKS) Exam 2

______ includes all cases, both new and pre existing, within a population at the specified

time

Prevalence

______ is the number of newly diagnosed cases of a disease

Incidence

Relative Risk (RR) =

exposed / unexposed

1 multiple choice option

RR = 1

no / little difference in risk

RR > 1

increased risk of outcome in exposed group

RR < 1

reduced risk in exposed group

if CI contains 1.0, then the results are ________ and there is no difference in risk / odds.

NOT SIGNIFICANT

1 multiple choice option

Relative Risk Reduction (RRR) =

(ARc - ARt) / ARc

OR

1 - RR

Absolute Risk Reduction (ARR) =

ARc - ARt

number of patients who need to be treated in order to prevent one additional bad outcome

Number Needed to Treat (NNT)

Ideal NNT is ____, where everyone improves with treatment and no-one improves with control

1

The higher the NNT, the _____ effective the treatment is

less

1 multiple choice option

NNT =

1/ARR

The odds in favor of disease* among those exposed individuals divided by the odds in favor of

disease among the unexposed

Odds Ratio

OR =

ad/bc

2 multiple choice options

OR = 1 →

no association b/w a risk factor and disease (Exposure does not affect odds of the outcome)

OR > 1 →

strong pos. Association (Exposure associated w/ higher odds of outcome)

OR < 1 →

strong neg. Association (Exposure associated w/ lower odds of outcome)

In a study where the investigators looked at drug A to treat hypertension. When they looked at the side effect profile, they found the odds ratio of hyperkalemia was 1.8 (95% CI, 1.56-1.9). Which of the following statements is true about the study?

a. Drug A is associated with higher risk of hyperkalemia

3 multiple choice options

The risk of MI in patients taking low-dose ASA vs. placebo, the relative risk was 0.58 (95% Cl, 0.45-0.72). Is it true:

a. low-dose ASA reduced the risk of MI by 42%

2 multiple choice options

In a study comparing the use of rivaroxaban and enoxaparin to prevent VTE following hip

replacement surgery, the odds ratio (OR) for VTE was 0.28 (95% Cl, 0.20-0.40). Which of the following is true:

b. Rivaroxaban is associated with lower odds of VTE compared to enoxaparin

3 multiple choice options