# Attribute risk and strategies for prevention. Flashcards

1
Q

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?

A

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

2
Q

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

A

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

3
Q

What are absolute measures used for (2 things) ?

A
1. Policy decisions.

2. To allocate resources.

4
Q

Name three examples of absolute measures.

A
1. Risk difference.
2. CI.
3. Prevalence.
5
Q

What are relative measures used for?

A
1. To determine the strength of association.
2. To determine a causal relationship.
3. To explore aetiology.
6
Q

What does attributable risk assume (3 things)?

A
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).
7
Q

What does the attributable risk assess?

A

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

8
Q

Background exposure is a constant. True or false?

A

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

9
Q

What should you always state when stating the AR?

A

A time period.

10
Q

What is the formula for the AR?

A

AR= R1-R0.

11
Q

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

A

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

12
Q

What does NNT stand for?

A

Number needed to treat.

13
Q

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

A

1/AR.

14
Q

What is the definition of AR%?

A

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.

15
Q

What is the formula of the AR%?

A

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

16
Q

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

A

False. AR always refers to the exposed group.

17
Q

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

A

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

18
Q

What is the definition of the preventable fraction?

A

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

19
Q

What is the definition of population attributable risk?

A

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

20
Q

What are the equations used for PAR?

A

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

(Ipopulation- Iexposed)/ Ipopulation x100.

21
Q

What is the equation for Par%?

A

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

22
Q

What does Par% tell us?

A

The % of cases which could be prevented.

23
Q

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

A

False.

24
Q

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

A

When the proportion of exposed individuals within a population changes.

25
Q

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

A

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

26
Q

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

A

Within populations.

27
Q

What happens in a high risk intervention strategy?

A

Individuals at high risk are identified and treated.

28
Q

What happens in an intervention strategy targeting a whole population?

A

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).

29
Q

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

A

High risk strategies.

30
Q

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

A

High risk strategies.

31
Q

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

A

High risk strategies.

32
Q

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

A

High risk strategies.

33
Q

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

A

High risk strategies.

34
Q

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

A

Population strategies.

35
Q

What does the prevention paradox state?

A

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.