Screening Flashcards
what is screening
So it’s a process of identifying apparently healthy people who may be at increased risk of a disease or a condition
false positive
an individual referred for further assessment who DOES NOT have the target condition -
false negative
an individual not referred for further assessment who does have the condition - some high risk fall through
prevalence
number of individuals in a population with the target condition
number of people with the disease or condition at a specified time/ number of people in the population at risks at the specified time
what is sensitivity
refers to the screens ability to detect those individuals who do have the target condition
Perfect screen would be 100% sensitive – all individuals affected detected True
positives
ability to run out disease if test is negative
specificity
refers to the screens ability to not detect unaffected individuals
100% specific – all individuals without the target condition do not require further assessment True negatives
ability to rule in disease - if test is positive
Positive predictive value (PPV) is the probability that subjects with a positive screening test truly have the disease.
what is NPV
Negative predictive value (NPV) is the probability that subjects with a negative screening test truly don’t have the disease.
formula for true positive and true negative
true positive/ True positive + false positive
true negative / true native + false negative
sensitivity formular
TP/TP+FN
specificity
TN/TN+FP
If 96 affected and 4980 unaffected total 5076
for being positive
if 4 affected and 510,100 for negative
what is the specificity and sensitivity
sensitivity 96/96+4 = 96%
the probability of the screening test correctly identifying diseased subjects was 96%
specificity 510,100/510,100+4980 = 99%
The probability of the screening test correctly identifying non-diseased subjects was 99%
PPV 96/96+4980 =2%
NPV 510,100/510,100+4 = 99.99%
quadruple test
downs only
