Diagnostic Tests Screening for Disease Flashcards
1
Q
DPCP
A
Detectable Pre-clinical phase
2
Q
What diseases are appropriate for screening?
A
- serious disease w/severe consequences
- disease must be progressive,
- early tx is more effective at earlier stage
- prevalence of disease in the DPCP is high
3
Q
What are Characteristics of a Good Screening Test
A
- Economical
- Convenient
- relatively free of risk & discomfort
- acceptable to a large number of individuals
- Highly valid & reliable
4
Q
What is test sensitivity?
A
- proportion of those w/disease who test positive in the screened group
- Of those who really had disease, how frequently did the test correctly identify the problem?
- Probability that people with disease will have a positive test
- true positive (TP)
5
Q
Test reliability
A
- same result each time
6
Q
test specificity
A
- proportion of those w/o disease who test negative in screened group
- of the people who were normal, how frequently did the test correctly inform that they were ok?
- Probability that people without the disease will have a negative test
- true negative
7
Q
How to set up a 2x2 to test the quality of a test
A
8
Q
How do you calculate positive predictive value
A
- likelihood that a positive test result indicates the existence of the disease
- focuses on all people with positive test results
9
Q
How do you calculate negative predictive value?
A
- Likelihood that a negative test result indicates no disease
- focuses on all people w/negative test results
10
Q
What do predictive values depend on?
A
- Sensitivity
- Specificity
- Prevalence of disease in the population being tested
11
Q
What are the hazards of screenings?
A
- False Positive:
- worry
- risk
- cost
- inconvenience of dx test
- False Negatives:
- false reassurance
12
Q
What are the consequences of a False Negative
A
- false sense of security at best
- might neglect future screening tests
13
Q
What are the consequences of a false positive
A
- 3-5%=large on population level
- follow up tests
- cost
- potential harm
- anxiety
