Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Population Health > Lecture 26: Screening; A Special Type Of Prevention Strategy > Flashcards

Lecture 26: Screening; A Special Type Of Prevention Strategy Flashcards

1
Q

What is an example for primary prevention screening?

A

Screening women for alcohol intake to prevent breast cancer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is an example of secondary prevention screening?

A

Breast cancer screening (detects early stage of disease and aims to prevent more serious disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the screening test like?

A

Less expensive, less invasive (so effective on large population)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What’s the diagnostic test like?

A

It’s called a gold standard
Often invasive
Expensive
Impractical for large populations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens after the gold standard diagnostic test?

A

Disease positive get the intervention or treatment

Disease negative get rescreened after a specific period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens to test negative after first screen?

A

They get rescreened after a specific period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 4 screening criterion?

A
  1. Suitable disease
  2. Suitable test
  3. Suitable treatment
  4. Suitable screening time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Two features of a suitable disease?

A
  1. An important public health problem

2. Knowledge of the natural history of the disease (or relationship of risk factors to the condition)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Is a suitable disease common or uncommon?

A

It can be either- if it’s effective and easy, uncommon screenings can occur (eg babies screened for pku)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why do we screen for uncommon disease too?

A

Because if we have an early detection and intervention we can get a better outcome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is knowledge of the disease important for screening?

A

So we know it’s detectable early with a detectable risk factor/disease market and needs an increased duration of preclinical phase (after biological onset, before clinical diagnosis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Examples of screening?

A

Breast cancer, cervical cancer, diabetes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the key aspects of a suitable test?

A
  1. Reliable
  2. Safe
  3. Acceptable
  4. Simple
  5. Cheap
  6. Accuracy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is accuracy?

A

The ability of a test to indicate which individuals have the disease and which don’t

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Two measures of accuracy?

A

Specificity

Sensitivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What two types of tests are used?

A

Screening test

Gold standard test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the gold standard?

A

Is in effect the ideal diagnostic test (example: colonoscopy). Is expensive and invasive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a general screening test?

A

(A less expensive diagnostic test) eg faecal occult blood test (for colon cancer)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the gate frame screening SQUARE

A

Top left: true positive
Bottom left: false negatives
Top right: false positives
Bottom right: true negatives

20
Q

What is sensitivity?

A

The ability to identify correctly those who have the disease (a) from all individuals who have the disease (a+c)

The likelihood of a positive test in those with the disease

21
Q

What is specificity?

A

The ability of the test to identify correctly those who do not have the disease (d) from all individuals who don’t have the disease (b+d)

22
Q

Sensitivity calculation?

A

True positives/all with disease x100

A/(a+c) x100

“X% of those with the disease will test positive in the new test”

23
Q

Specificity calculation?

A

True negatives/all without the disease
= b/(b+d) x 100

“X% of those without the disease will have a negative result in the new test”

24
Q

How do we evaluate test accuracy?

A
  • the sensitivity is high if the proportion of true positives are high
  • the specificity is high if the number of true negative are high
25
Q

What are the fixed characteristics of a new test?

A

Sensitivity and specificity

26
Q

What are the two predictive values?

A

Positive predictive value
(PPV)
Negative predictive value (NPV)

27
Q

Why are sensitivity and specificity different between populations?

A

Because the prevalence of disease is different in different populations

28
Q

So what is a predictive value?

A

How well a new screening test works in a specific population

29
Q

What does the positive predictive value measure?

A

Out of everyone who tests positive (false and true), how many truly have the disease?

Or the probability of having disease if the test is positive

30
Q

Calculation for the positive predictive value?

A

True positives/all who test positive x100

Or

A/(a+b) x100

31
Q

Why is a low predictive value bad?

A

Because of the emotional and monetary cost of getting a false positive

32
Q

What is negative predictive value?

A

The proportion of people who truly don’t have the disease out of everyone who test negative

Or the probability of not having the disease if you test negative

33
Q

Calculation of negative predictive value?

A

Number of people truly with out disease/everyone who tests negative x100

Or

D/(c+d) x100

34
Q

Are PPV and NPV fixed test characteristics?

A

No

35
Q

What do positive predictive values and negative predictive values reflect?

A

Test accuracy and the prevalence of the disease

36
Q

Why is suitable treatment a necessary aspect of screening?

A

No point if no treatment to improve chances

37
Q

What is suitable treatment criteria?

A
  • evidence of early treatment leading to better outcomes
  • effective, accessible and acceptable treatment
  • evidence-based policies covering who should be offered treatment and the appropriate treatment to be offered (don’t create disparities)
38
Q

What is a suitable screening programme?

A
  • when benefits must outweigh harm
  • when randomised control trials have provided evidence that the screening programme will result in:
  • reduced mortality
  • increased survival time
39
Q

What are two types of bias sometimes present in screening programme?

A
  • lead bias

- length time bias

40
Q

What is lead time bias?

A

When there’s an “apparent increase in life expectancy or lead time” by screening, but just because you identify it early, doesn’t mean you’re increasing length of survival (ie still could be a fixed death point)

41
Q

Do what aspect can give a screening programme a false impression of success?

A

If the screening programme is evaluated in terms of survival time

42
Q

What is length time bias?

A

Could be two firms of a disease (eg slow and rapid), and screening might say they have an increased/longer average survival rate if they’re using data from people with slow disease (and miss those with rapid, due to death etc)

43
Q

Criteria of a suitable screening programme?

A
  • benefits outweigh harm
  • RCT evidence that screening programme will result in increased survival/reduced mortality
  • adequate resourcing and agreed policy for test/diagnosis/treatment/programme management
  • cost effective
  • healthcare system must support all elements of screening pathway
  • needs to reach all those likely to benefit from it (specific initiatives for particular population groups)
44
Q

How is breast cancer a suitable disease for screening?

A
  • NZ high risk
  • common among women
  • Maori have high rates
  • also pacific women have high rates
  • incidence rates increase at age 50+
45
Q

How is breast cancer screening a suitable test ?

A

Screening mammogram:
Detects lumps in breast
Sensitivity=75-90%
Specificity= 90-95%

46
Q

How is breast cancer screening suitable treatment?

A

There’s surgical treatment and a 5 year survival rate of 95-100%

47
Q

How is the breast screen programme suitable in NZ?

A

“Breast screen Aotearoa”:
Women who test positive get the diagnostic test
Reduces cancer mortality by 20% (under 50), 30% (50-65), 45% (65-69)
Specific goal for Maori/Polynesian
10 year survival rates

Population Health (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions