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611: Research in Physical Therapy I > Principles and Predictive Value of Screening > Flashcards

Principles and Predictive Value of Screening Flashcards

1
Q

What is screening?

A

the application of a test to people in order to assist with early identification of a disease.

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2
Q

What is the objective of screening?

A

to reduce mortality and morbidity with early detection

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3
Q

Good Screening Programs screen for health problems that….(6 things)

A
  • Are important to the individual and community
  • Have an acceptable form of treatment
  • Has a natural history that is adequately understood
  • Has a recognizable latent or early symptomatic stage
  • Has a suitable screening test
  • Is economically beneficial
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4
Q

3 Requirements of Screening Tests

A
  • Ideally should be inexpensive
  • easy to administer (low risk)
  • minimal discomfort
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5
Q

What are screening tests based off of?

A

a Gold Standard based on the evidence

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6
Q

Results of a screening test should be ____ and ____

A

Accurate / Valid
and
Reliable / Precise

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7
Q

Define Accuracy (Validity)

A

The degree to which a variable actually represents what it is supposed to represent

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8
Q

What is the best way to assess validity?

A

compare results to a reference standard

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9
Q

What threatens validity?

A

Systematic error (aka bias)

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10
Q

Define Precision (Reliability)

A

The degree to which a variable has nearly the same value when measured several times

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11
Q

What is the best way to assess precision?

A

repeated measures

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12
Q

What threatens precision?

A

Random Error

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13
Q

What determines our predictive value?

A

Sensitivity, Specificity and the Prevalence of the disease

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14
Q

Define the prevalence of a disease

A

Represented by the number of patients per 100,000 population who have the disease at a given time

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15
Q

How do we determine the validity (accuracy) of a screening test?

A

Determine its sensitivity and specificity

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16
Q

Define sensitivity

A

The fraction of those with the disease that are correctly identified as positive by the test

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17
Q

What does sensitivity determine?

A

Whether or not the test detects true cases of the disease
For example: if you have 100 people with meniscus tears and after performing a meniscal teat test you get a positive meniscus tear 90 times the sensitivity of this screening test is 0.9

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18
Q

Define specificity

A

The fraction of those without the disease correctly identified as negative by the test.

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19
Q

What does specificity determine?

A

Whether or not the test excludes those without the disease

20
Q

How is data estimating sensitivity and specificity typically displayed?

A

in a 2 x 2 table that classifies people according to their disease status and test results

21
Q

What are true positives?

A

people who have the disease and whose test came up positive

22
Q

What are true negatives?

A

the people who do not have the disease and whose test came up negative

23
Q

What are false negatives?

A

the people who have the disease but their test came up negative

24
Q

What are false positives?

A

the people who do not have the disease but their test came up positive

25
Q

Given true and false positives and true and false negatives how can we determine sensitivity?

A

= number of true positives / total number of those with the disease

26
Q

Given true and false positives and true and false negatives how can we determine specificity?

A

= number of true negatives/ total number of those that do not have the disease

27
Q

What is Positive predictive value (+PV)?

A

The fraction of people with positive tests who truly do have the condition.

28
Q

What is negative predictive value (-PV)?

A

The fraction of people with negative tests who truly don’t have the condition.

29
Q

Given true and false positives and true and false negatives how can we determine +PV?

A

= number of true positives / total number of positive test results (both true and false)

30
Q

Given true and false positives and true and false negatives how can we determine -PV?

A

= number of true negatives / total number of negative test results (both true and false)

31
Q

The sensitivity and specificity are properties of the _____.

A

test

32
Q

The positive and negative predictive values are properties of the _____and the _______you test.

A

test and population you test

33
Q

If you use a test in two populations with different disease prevalence will the predictive values will be the same or different?

A

different

34
Q

When is a screening test most useful?

A

if directed to a high-risk population (high prevalence and high predictive value)

35
Q

When you know your patient has the disease and you want to know what is the chance that the test will show that my patient has it what are you trying to determine?

A

Sensitivity

36
Q

When you know your patient doesn’t have the disease and you want to know what is the chance that the test will show that my patient doesn’t have it what are you trying to determine?

A

Specificity

37
Q

When you receive a positive test result back and you want to know what is the chance that your patient actually has the disease what are you trying to determine?

A

Positive Predictive Value

38
Q

When you receive a negative test result back and you want to know what is the chance that your patient actually doesn’t the disease what are you trying to determine?

A

Negative Predictive Value

39
Q

What does a high PPV indicate?

A

There is a strong chance that a person with a positive test has the disease

40
Q

What does a high NPV indicate?

A

A negative test will rule out the disease

41
Q

What can you typically conclude with a low PPV?

A

There is a low prevalence of the disease in the population being examined

42
Q

When a sign, test or symptom has an extremely high specificity what does a positive test result tend to do?

A

rule IN the diagnosis

SpPIn (specificity, positive, in)

43
Q

When a sign, test or symptom has an extremely high sensitivity what does a negative test result tend to do?

A

rule OUT the diagnosis

SnNOut (sensitivity, negative, out)

44
Q

Define systematic review

A

systematically identifies and appraises all quality research evidence that is relevant to your particular research question

45
Q

Define Meta Analysis

A

a quantitative statistical analysis of several separate but similar experiments that tests the pooled data for statistical significance

46
Q

Meta analysis determines what between treatments?

A

progress

47
Q

What does meta analysis use?

A

effect size to determine the difference among groups

611: Research in Physical Therapy I (16 decks)

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