Screening tests are designed to identify the presence of a disease or condition in people who have no symptoms, while diagnostic tests are used to confirm the presence of a disease or condition in people who have symptoms. Screening tests are usually simpler and less invasive than diagnostic tests, and are performed on a large population to identify potential cases of a disease. On the other hand, diagnostic tests are more comprehensive and specific, and are used to determine the cause of symptoms in an individual. In summary, screening tests are used for early detection, while diagnostic tests are used for confirmation and determination of a disease.
Differences between screening and diagnostic tests
Here’s a table that summarizes the differences between screening tests and diagnostic tests:
|Feature||Screening Test||Diagnostic Test|
|Purpose||To identify potential cases of a condition in a population||To confirm or rule out the presence of a condition in an individual|
|Target Population||Asymptomatic individuals or those with non-specific symptoms||Individuals with specific symptoms or a positive screening test|
|Timing||Typically performed before symptoms appear||Typically performed after symptoms appear or after a positive screening test|
|Sensitivity||Low (may miss some cases)||High (designed to accurately diagnose the condition)|
|Specificity||High (few false positives)||High (designed to accurately diagnose the condition)|
|Invasiveness||Non-invasive or minimally invasive||May be invasive (e.g. biopsy)|
Note: Sensitivity refers to the ability of a test to correctly identify individuals with the condition, while specificity refers to the ability of a test to correctly identify individuals without the condition.
Case finding refers to the process of identifying and diagnosing individuals who have or are at risk of developing a specific health condition. It involves the use of various screening and diagnostic tests to identify cases that may otherwise go unnoticed. The goal of case finding is to diagnose and treat conditions early, before they become more severe, to improve health outcomes and prevent the spread of disease.
Opportunistic screening refers to the practice of offering screening tests (such as medical tests, exams, or assessments) to individuals during routine healthcare visits, rather than only as part of a targeted screening program. The aim of opportunistic screening is to increase the detection of early cases of a disease or condition and to improve health outcomes by catching them at an early stage when treatment is more likely to be effective. Examples of opportunistic screening include cholesterol testing during a routine physical exam or mammography screening during a routine gynecological exam.
Dr. Miryam Ishak