Brainscape's Knowledge GenomeTM

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


See full index

EPI > Interpreting Data Regarding Correlations, Risk Factors, Prevention, and Therapy > Flashcards

Interpreting Data Regarding Correlations, Risk Factors, Prevention, and Therapy Flashcards

1
Q

what is the correlation coefficient (r)

A

mathematical expression of strength and direction of correlation between variables

  • range from -1 to +1
  • +/-0.5 indicates a weak correlation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

interpret:

a study of the amount of smoking and the incidence of lung cancer generates a correlation coefficient of r=+0.7

A

indicates a strong positive correlation

ie: increased amounts of smoking are strongly associated with an increased incidence of lung cancer

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

pearson product-moment correlation (r) is used for:

spearman rank-order correlation (rho) is used for:

A

continuous data

ordinal scale data

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

how is correlation represented

A

scattergrams

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

what is the correlation of determination

A

expresses the proportion of variance in a variable explained by another variable

r^2, expressed as a percentage

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

interpret:

correlating exercise levels with serum glucose levels generates r=-0.4, squaring this value results in a coefficient of determination of 0.16 (16%)

A
  • indicates that 16% of the variance in serum glucose levels can be accounted for by the exercise level
  • this correlation is weak and doesnt necessarily mean that increased exercise causes a decrease in serum glucose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is regression analysis

linear regression

multiple regression

A

a mathematical technique used to predict the value of one variable based on another
–> only useful in highly correlated variables

linear: predicts one variable based on another
Multiple: predicts the value of a variable based on multiple covariates (ex rate of heart attack based on cholesterol, bp, weight, age) & adjusts data to eliminate effects of confounding vars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the ways to measure effects of risk factors?

A 
odds ratio (OR)
absolute risk (AR)
attributable risk 
relative risk (RR)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the odds ratio

A

measures the degree of association of a risk factor with a disease or outcome

  • ratio of the odds that a case was exposed to the odds that a control was exposed
  • used when actual incidence of a disease is not measured, such as case-control

=odds that a case was exposed to risk factor/odds that control was exposed to risk factor

= (#obese diabetic/#nonobese diabetic)/(#non-diabetic obese/# non-diabetic non-obese)

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

=odds that a case was exposed to risk factor/odds that control was exposed to risk factor

A

odds ratio (OR)

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

what does odds ratio show

A

shows an association between risk factors and condition, but is a relatively weak indicator of causality

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

what is the absolute risk (AR)?

A

the risk over a given time period of contracting a disease

  • synonymous with incidence
  • done for control group and for experimental group

=number developing disease/total number

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

=number developing disease/total number

A

absolute risk (AR)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is attributable risk?

A

the difference in risk between exposed and unexposed groups
-the amount of disease ocurrances that are attributable to the exposure

=AR (exposed) - AR (unexposed)

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

=AR (exposed) - AR (unexposed)

A

attributable risk

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

what is relative risk?

A

measures how many times exposure to a risk factor increases the risk of contracting a disease
-ratio of the absolute risk of disease among those exposed to absolute risk among those not exposed to the risk factor

  • can only be calculated when incidence is measured (such as cohort study)
  • -> shows not only association but is a more powerful indicator of causality

=AR of disease among exposed/AR of disease among non-exposed

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

=AR of disease among exposed/AR of disease among non-exposed

A

relative risk

18
Q

measures how many times exposure to a risk factor increases the risk of contracting a disease
-ratio of the absolute risk of disease among those exposed to absolute risk among those not exposed to the risk factor

A

relative risk

19
Q

the risk over a given time period of contracting a disease

  • synonymous with incidence
  • done for control group and for experimental group
A

absolute risk

20
Q

the difference in risk between exposed and unexposed groups

-the amount of disease occurrences that are attributable to the exposure

A

attributable risk

21
Q

Interpret:

a cohort study investigating obesity as a risk factor for diabetes determines a relative risk of 5

A

obese are 5X as likely to develop diabetes compared to non-diabetes

22
Q

interpret

attributable risk of obesity to diabetes is 16%

A

16% of risk for diabetes comes from obesity

23
Q

what are the ways to interpret data regarding prevention and therapy?

A

relative risk reduction
absolute risk reduction
number needed to treat
cost of intervention

24
Q

what is relative risk reduction (RRR)

A

measures the decrease in relative risk due to an intervention

=1-relative risk

25
Q

measures the decrease in relative risk due to an intervention is:

A

relative risk reduciton

26
Q

=1- RR

A

relative risk reduction

27
Q

interpret:

obese patients are treated with an aggressive diet/exercise program. compared to controls the treated patients are found to have a RR of 0.25. the RRR is thus 1-0.25=0.75. what does this mean?

A

treatment reduced the relative risk by 75%

28
Q

what is absolute risk reduction (ARR)

A

decrease in absolute risk (decrease in incidence) of an outcome due to an intervention

=AR(Control) - AR (treatment)

29
Q

=AR(Control) - AR (treatment)

A

ARR

30
Q

decrease in absolute risk (decrease in incidence) of an outcome due to an intervention is:

A

ARR

31
Q

interpret:

obese patients are treated with an aggressive diet/exercise program. controls are found to have an AR of diabetes of 0.4. The study group AR of diabetes is 0.1. The ARR is 0.4-0.1=0.3. what does this mean

A

the treatment reduced the absolute risk by 30%

32
Q

what is the difference between ARR and attributable risk? (they are calculated the same way..)

A
  • AR is generally used when assessing impact of risk factors

- ARR is generally used when accessing the impact of prevention/treatment

33
Q

What is the difference between RRR and ARR?

A
  • RRR is how many times exposure to a risk factor increases risk of contracting disease
  • -> higher, more impressive number than ARR
  • ARR is the decrease in absolute risk of an outcome due to an intervention
  • -> smaller, less impressive than RRR

but ARR is more clinically relavant

34
Q

why is ARR more clinically relevant than RRR

A

it incorporates the incidence of the disease/outcome being prevented

35
Q

what is the number needed to treat (NNT)

A

calculation of the number of patients who would be required to receive treatment in order to prevent one negative outcome

=1/ARR

36
Q

=1/ARR

A

NNT

37
Q

calculation of the number of patients who would be required to receive treatment in order to prevent one negative outcome

A

NNT

38
Q

interpret:

ARR for obese patients receiving aggressive diet and exercise was found to be 0.3. Calculate NNT. what does this mean?

A

NNT= 1/0.3 = 3.3

this means that 3.3 patients would need to receive treatment in order to prevent one case of diabetes

39
Q

what is the cost of intervention

A

a calculation of the cost of preventing one negative outcome

=NNTx cost of 1 intervention

40
Q

what is quality of life years (QALY)

A

measure of length of life weighed by a valuation of health related to quality of life

  • quality of life modifier is calculated based on questions regarding ability to walk, self care, ability to perform usual activities, pain, anxiety, depression.
  • generally this number ranges from 0-1, 1 is perfect health

EPI (7 decks)

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