Attribute risk and strategies for prevention.

Question 1

If a risk ratio of disease A and odds ratio of disease B are equal in value then the association seen in both diseases are the same. True or false?

Answer 1

False. A risk ratio shows stronger association as the odds ratio is always further from the null.

Question 2

Why do you need to take into account relative ratios instead of just using association measures?

Answer 2

As relative measures are needed to take into account impact at the population level.

Question 3

What are absolute measures used for (2 things) ?

Answer 3

1. Policy decisions.

2. To allocate resources.

Question 4

Name three examples of absolute measures.

Answer 4

1. Risk difference.
2. CI.
3. Prevalence.

Question 5

What are relative measures used for?

Answer 5

1. To determine the strength of association.
2. To determine a causal relationship.
3. To explore aetiology.

Question 6

What does attributable risk assume (3 things)?

Answer 6

1. Causal relationship.
2. No source of bias.
3. The distribution of other known and unknown factors is the same in exposed and unexposed groups (this includes background exposure).

Question 7

What does the attributable risk assess?

Answer 7

The impact of removing the exposure from the whole population or from exposed individuals.

Question 8

Background exposure is a constant. True or false?

Answer 8

It is true in a given population but varies between populations.

Question 9

What should you always state when stating the AR?

Answer 9

A time period.

Question 10

What is the formula for the AR?

Answer 10

AR= R1-R0.

Question 11

When will you use the term ‘risk difference’ instead of ‘attributable risk’?

Answer 11

When you do not know if the exposure is a causal factor.

Question 12

What does NNT stand for?

Answer 12

Number needed to treat.

Question 13

What formula for NNT is needed to prevent one case of disease?

Answer 13

1/AR.

Question 14

What is the definition of AR%?

Answer 14

The proportion of disease in the exposed group that can be attributed to the exposure of interest. This proportion of disease could be removed if you removed the exposure.

Question 15

What is the formula of the AR%?

Answer 15

(Iexposed-I unexposed)/1exposed = (RR-1)/RR x100.

Question 16

You should always define AR correctly so you know if you are referring to the exposed or unexposed group. True or false?

Answer 16

False. AR always refers to the exposed group.

Question 17

If an exposure is protective you use a negative RD value. True or false?

Answer 17

False. You can but it is better to switch the exposed and unexposed group.

Question 18

What is the definition of the preventable fraction?

Answer 18

The proportion of cases that would have occurred if people had not been exposed to a protective factor. This occurs when RR<1.

Question 19

What is the definition of population attributable risk?

Answer 19

The excess risk of disease in the total study population. The number of cases that could be prevented if the risk factor was removed.

Question 20

What are the equations used for PAR?

Answer 20

AR x Pe (proportion of exposed people in the population).

(Ipopulation- Iexposed)/ Ipopulation x100.

Question 21

What is the equation for Par%?

Answer 21

P(RR-1)/P(RR-1) +1

Question 22

What does Par% tell us?

Answer 22

The % of cases which could be prevented.

Question 23

A big AR correlates with a big PAR? True or false?

Answer 23

False.

Question 24

When will the same AR% give rise to a different population risk?

Answer 24

When the proportion of exposed individuals within a population changes.

Question 25

What can the difference in means of different populations with a different distribution of a risk factor tell you?

Answer 25

The average effect of the environment and or lifestyle on the characteristic under study. Genetic differences are assumed to cancel out.

Question 26

Are genetic variants greater between populations or within populations (most of the time).

Answer 26

Within populations.

Question 27

What happens in a high risk intervention strategy?

Answer 27

Individuals at high risk are identified and treated.

Question 28

What happens in an intervention strategy targeting a whole population?

Answer 28

The entire distribution of a risk factor within a population is shifted through addressing the underlying causes. This may not be beneficial is low values of a factor also result in a risk (eg too low a BMI).

Question 29

Are high risk strategies or population strategies integrated with medical care?

Answer 29

High risk strategies.

Question 30

Do high risk strategies or population strategies have a high benefit-to-risk ratio?

Answer 30

High risk strategies.

Question 31

Do high risk strategies or population strategies offer a small contribution to the control of a disease?

Answer 31

High risk strategies.

Question 32

Do high risk strategies or population strategies result in prevention being medicalised (which is a negative thing)?

Answer 32

High risk strategies.

Question 33

Do high risk strategies or population strategies result in temporary and palliative success?

Answer 33

High risk strategies.

Question 34

Do high risk strategies or population strategies offer a small individual benefit?

Answer 34

Population strategies.

Question 35

What does the prevention paradox state?

Answer 35

That a large number of people exposed to a low risk generate more cases than a small number of people exposed to a high risk. A measure that brings large benefits to the community offers little to each participating individual.