Test Validation Flashcards by Sonography ♡

What is the statistical parameters which allows you to have a rationale for judging the effectiveness of a particular diagnostic test, such as a sonographic examination, referred to as?

(Trying to determine if a test can be utilized in place of the Gold Standard)

Test validation

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In order for a test to be effective, it must either (blank) or (blank)

Selectively identify patients with the specific disease

Selectively rule out patients as not having the specific disease (like a screening test)

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List the three parameters commonly used to judge the efficiency of a diagnostic test:

Sensitivity, specificity, and accuracy

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What is the standard that all tests are compared to, and definitely tells physicians whether or not a patient has a specific ailment?

Gold Standard

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List an example of the gold standard being used:

Histology from a biopsy indicating a cancerous mass

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What is used to when there is not a gold standard to compare to?

If there is no gold standard test, then either

An autopsy
clinical information/findings during surgery are used

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What is the gold standard for a carotid artery stenosis (CAS)?

Digital subtraction angiography (DSA)

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In what scenario would u/s not be able to detect a CAS, resorting to the gold standard?

u/s may or detect CAS in cases of too much shadowing from plaque (can’t see narrowing)

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In what scenario would u/s not be able to detect a DVT, resorting to the gold standard?

U/s may not detect blood clots in situations where patient has too much fluid in the body (edema) to penetrate via u/s

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What is the gold standard for a DVT?

Venography/venogram

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What is the term for when the testing procedures demonstrates disease and the disease is really present?

True Positive (TP)

(Test and GS agree there is pathology)

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List an example of a “true positive” finding:

Both a BLEVDOPP u/s and a venogram agree there is pathology

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What is the term for when the testing procedures demonstrates no disease, and no disease is present.

True Negative (TN)

Both the test and GS agree there is no pathology.

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What is the term for when the testing procedures demonstrates disease that is not really present?

I.e. the test said abnormal (pathology), but the gold standard said normal (no pathology)

False positive

Test being evaluated is falsely positive

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List an example of a false positive

VDOPP u/s indicated DVT, but Venogram (GS) was normal.

Thus, there wasn’t really any pathology.

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Term for when the testing procedures demonstrates the presence of no disease, and disease is actually present.

I.e. The test said normal (no pathology), but the gold standard said abnormal (pathology)

False negative

Test being evaluated is falsely negative

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Which parameter is a measurement of how real a disease finding by that exam is?

Specificity

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Which parameter is a measurement of how often a test will miss real disease?

Sensitivity

(Positive)

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What is the ability of a test to detect a disease?

Sensitivity

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What is the ability of a test to identify normality (rule out pathology)?

Specificity

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What is the formula for sensitivity?

True positives (TP) divided by true positives (TP) plus false negatives (FN)

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T/F

Low sensitivity is acceptable if known.

False

Low sensitivity is dangerous; patients who are positive may not receive the treatment they need

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What is the term for how much you can trust a test?

Study These Flashcards

Specificity

Minimizing false-negatives will increase the (blank)

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Sensitivity

List the formula for specificity:

True negatives (TN) divided by true negatives (TN) plus false positives (FP)

Decreasing false-positives will increase (blank)

Specificity

Which parameter quantifies the ability to give the correct answer of how well a test can detect and rule out disease?

Overall accuracy

Which parameter is a proportion of the sample population who have the pathology or condition being tested for?

Prevalence

Describe overall accuracy in your own words:

How many times both of the exams agreed that a test was negative or positive

List the formula for Overall Accuracy:

True positives (TP) plus True Negatives (TN) divided by Total # of Tests.

T/F Prevalence is a parameter than can effectively be used to validate your test.

FALSE Prevalence does NOT validate your test!!!

List the formula for prevalence:

True Positives (TP) plus False Negatives (FN) divided by total # of tests

Term for the parameter which gives the percentage of studies that correctly predicted disease as supported by the gold standard.

Positive predictive value (PPV) A measurement of how meaningful a positive result really is

T/F Tests that have a low PPV may NOT be useful in any capacity.

False. Tests with a low PPV can be useful as an initial screening test, but further testing may be recommended before treatment.

List the formula for PPV:

True Positives (TP) divided by True positives (TP) plus False Positives (FN)

What is the parameter which gives the percentage of negative studies that correctly predicted absence of disease as supported by the gold standard?

Negative Predictive Value (NPV) A measurement of how meaningful a negative result really is

T/F A test with a low NPV is likely to miss disease

True A test with a low NPV should be used as a last resort to avoid endangering the patient by delaying their diagnosis.

Which parameters should only be given in a percentage or fraction?

PPV and NPV

List the formula for NPV:

True Negatives (TN) divided by True Negatives (TN) plus False Negatives (FN)

List the factors that are important for an Initial screening test:

-Must have high sensitivity -Must have low False Negative rate -Must be low risk & minimally invasive -Must be low cost, timely, and available -Must not send anyone with the pathology away with a negative result

T/F Initial screening tests must be able to provide adequate information on the area and extent of the disease.

False. Initial screening tests provide LITTLE information on area and extent of disease.

Which type of testing prevents disease from progressing and prolonging a diagnosis that can be treated?

Initial screening test.

What is another term for sensitivity?

The miss rate

List the factors which are important for a diagnostic test:

-Must have high specificity -Must have low False Positive (FP) rate -Must always be correct about pathology, as treatment will be based on this. -Must have known diagnosis

In diagnostic testing, why is low sensitivity (miss rate) acceptable only if it is known?

—As long as it is known, you can interpret it cautiously. —You know that a negative result doesn't rule out disease. —You’d likely follow up with: A more sensitive test Further imaging or lab work

In what scenario would diagnostic testing be skipped?

When the initial screening tests provides enough information to reliably plan surgery/treatment Ex: cholelithiasis, ectopic pregnancy, apply, etc.

The passing of traits from parent to offspring

Heredity

Two inherited alleles together to form an organism

Genotype

Physical appearances for a given characteristic

Phenotype

An inherited trait that results from the expression of the dominant allele over the recessive allele

Dominant traits

Trait/gene that is only expressed when an organism has two recessive alleles, or forms a gene.

Recessive trait (Note; does not show up as often)

What is the genotype with two dominant OR two recessive alleles? (RR or rr)

Homozygous

What is the genotype with one dominant and one recessive allele (Rr)?

Heterozygous

Each square in a punnet represents:

25%

You must find the (blank) before you can find the phenotype using a punnet square.

Genotype

T/F If a dominant trait is in the square, the dominant gene will be present.

True

Test Validation Flashcards

(56 cards)