Measures Of Association

Question 1

980 females in Missouri had bypass surgery and 1640 males had the surgery as well over the past year. What is the absolute risk difference in males and females.

Answer 1

660. Straight subtraction

Question 2

What is the Absolute Risk Reduction?(attributable risk)

Answer 2

Difference of outcome due to exposure difference in the groups. Comparing an experimental group to placebo.
ABSOLUTE=subtract

Question 3

What is relative risk reduction?

Answer 3

Attributable risk divided by placebo unexposed group

Question 4

What is the NNT.

Answer 4

Number of patients needed to treat before one receives benefits. You want a low NNT and a high NNH.
ALWAYS round up
1/ ARR(decimal format)

Question 5

In a research study of a new drug the NNT was determined to be 87, what does this mean?

Answer 5

87 patients need to be treated before one receives the benefit

Question 6

A clinical trial was done to figure out the impact of dual treatment for hypertensive emergencies compared to single agent therapy. The study found the risk of death from hypertensive emergency in the dual was 9% compared to 10% in single agent. Describe the proper interpretation of the NNT.

Answer 6

A total of 100 patients would need to be treated with the double agent therapy to reduce one death.

1/ARR
.10-.9=.01
1/.01= 100

Question 7

What is the risk ratio? (Relative risk RR)

Answer 7

Ratio of the risks in two different groups

Risk of exposed/risk In not exposed

Question 8

What does it mean if a risk ratio is less than one? Say RR=0.65

Answer 8

The group in numerator has a 35% reduced chance of experiencing the event than the placebo group.

Question 9

In a study the RR was found to be 4.6, interpret.

Answer 9

The numerator group is 4.6 times more likely than the control to experience the event.

Question 10

An outbreak of unknown origin occurs at the 2020 olympics. 345,000 are in attendance and there are 200,000 confirmed cases. 100,000 test positive for pathogen,but aren’t clinically sick. Of the confirm d cases 40,000 die. What is the virulence of this pathogen?

Answer 10

40,000/200,000= 20%

Question 11

In 2016 pancreatic cancer was 13% of all deaths in the US. What would this be referred to as?

Answer 11

Cause specific mortality

Question 12

13% of US deaths come from pancreatic cancer. The US pop is 300 million and there is a crude mortality rate of 15%. A total of 8 million pancreatic cancer cases were reported. What was the case fatality rate?

Answer 12

crude mortality= 300mil. X 0.15=45 million deaths
0.13x45 million deaths =5.85 million cancer deaths

5.85million/8million=73%