EBM Flashcards
What is sensitivity and specificity?
Sensitivity - the proportion of people with disease with a positive test result
Specificity - the proportion of people without disease with a negative result
What is a false negative result?
When a person has disease but the test gives a negative result, so the test wrongly shows that they do not have disease
What is a false positive result?
A person without disease has a positive result. The test wrongly shows that the person has disease even though they do not.
How to do calculate sensitivity and specificity?
Sensitivity (Positive) =
True positive / (True positive + False Negative)
(True positive / total positive results)
Specificity (Negative) =
True negative / (True negative + False positive)
(True negative / total negative results)
What is positive predictive value?
Positive predictive value (PPV): the proportion of those with a positive test result who actually have disease
True psi/Total negative(false negative+true negative)
What is a negative predictive value?
Negative predictive value (NPV): the proportion of those with a negative test result who do not have disease
True negative/Total negative(false negative+true negative)
What is reference standard?
Reference standard: the presence or absence of disease determined by approved methods
What is prevalence?
Prevalence: the amount of a particular disease in a population at a given point in time
People with disease/total number of people screened
What is screening?
IDENTIFYING apparently healthy people who may have an INCREASED CHANCE of a disease or condition. It is ALWAYS a PERSONAL CHOICE.
Why is it important to screen?
- Save lives
- Reducing chance of developing serious disease
- Helps us to make decisions about our health
- Give pregnant women advice about their reproductive choice
The screening programme should support personal informed choice and give screeningi information with this aim.
