Screening Test: A large number of apparently healthy people are tested to identify those who are at a risk of the condition or disease.
Diagnostic Test: When we get a screen positive individual or showing symptoms , we are interested to determine which condition or disease is responsible for such symptoms. Thus we perform a diagnostic test.
Sensitivity: probability that a person with the condition will be classified in one's study as having the condition.
Specificity: probability that a person without the condition will be classified in one's study as being without the condition.
I have not understood the statement from wikipedia :
" overdiagnosis, misdiagnosis, and creating a false sense of security are some potential adverse effects of screening. For these reasons, a test used in a screening program, especially for a disease with low incidence, must have good sensitivity in addition to acceptable specificity."
As far i can apply common sense for why screening test is more concerned about sensitivity is that , it is necessary to identify the people having the condition to minimize the risk or to prevent the condition. But what does
wikipedia want to mean by
overdiagnosis, misdiagnosis, and creating a false sense of security are some potential adverse effects of screening.Those are the reasons for why screening test is more concerned about sensitivity.
And the second and last question is
- why is diagnostic test more concerned about specificity ?
As i perform a diagnostic test when i get the symptom or positive screening test , then why do i need good specificity? Is that for , perhaps my study is on
cancer and an individual have some symptoms but the symptoms can be for another disease except cancer. So if i can identify the individual that s/he has not cancer, s/he will not be carried out for further experiment in my study. So that diagnostic testing is more concerned about specificity.
Do my logic make sense ?