Table of ContentsView AllTable of ContentsSensitivity and SpecificityRelevanceComparing TestsPositive/Negative Predictive ValueExamples
Table of ContentsView All
View All
Table of Contents
Sensitivity and Specificity
Relevance
Comparing Tests
Positive/Negative Predictive Value
Examples
In healthcare, sensitivity and specificity are terms used to describe how accurate a test is. A highly sensitive test is less likely to return a false negative result; a highly specific test is less likely to return a false positive result. These terms may be used to describe how confident your healthcare provider is in your test results.
Learn about sensitivity and specificity and how they are used to select appropriate testing and interpret the results.
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Sensitivity and Specificity in Medical Tests
Medical testing is an important tool that helps healthcare providers diagnose health conditions. Sometimes there is more than one potential diagnosis, and a medical test can help narrow down the possibilities.
Screening tests are another type of medical test that can help identify diseases that you may be at higher risk of developing.They are not done to diagnose a symptomatic illness, but to find a health condition that may not yet be producing symptoms.
The selection of these tests may rely on the concepts of sensitivity and specificity, which is a way to describe how accurate they are at confirming the suspected diagnosis.
Personal risk factors may increase the risk of an unidentified disorder and suggest earlier or more frequent screening. These factors include family history, sex, age, and lifestyle.
The decision to use one test over another requires careful consideration of both sensitivity and specificity. This helps healthcare providers and patients make the best decisions about testing and treatment.
Why Is Sensitivity and Specificity Important?
Not every test is useful for diagnosing a disease. A healthcare provider must carefully select the most appropriate test for an individual based on specific risk factors.
Choosing the wrong test may be useless, and a waste of time and money. It may even lead to a false positive test, suggesting a disease that is not actually present.
When medical research develops a new diagnostic test, scientists try to understand how effective their test is at properly identifying the target disease or condition. Some tests may not find a disease often enough in patients who are really sick. Others may incorrectly suggest the presence of a disease in someone who is actually healthy.
Healthcare professionals take into consideration the strengths and weaknesses of tests. They try to avoid any choices that might lead to the wrong treatment.
For example, in diagnosing someone with cancer, it may be important not only to have an image that suggests the presence of the disease, but a tissue sample that helps to identify the characteristics of the tumor so the right chemotherapy may be used.It would be inappropriate to solely depend on a single test that is not accurate in identifying the presence of cancer, and then start a treatment that may not really be needed.
In situations where one test is less than certain, multiple tests may be used to increase the confidence of a diagnosis.
It may seem logical that both a false negative and false positive should be avoided. If the presence of a disease is missed, treatment may be delayed and real harm may result. If someone is told they have a disease that they do not the psychological and physical toll may be significant.
It would be best if a test had both a high sensitivity and a high specificity. Unfortunately, not all tests are perfect. It can be necessary to find a balance that matches the purpose of the testing to the individual being evaluated.
The best test (or group of tests) for diagnosing a disease is called the gold standard.This may consist of the most comprehensive and accurate testing or measurements available.
In some cases, the purpose of the test is to confirm the diagnosis, but some testing is also used more widely to identify people at risk for specific medical conditions.
Screeningtakes place when a medical test is given to a large population of patients, with or without current symptoms, who may be at risk for developing a specific disease. Some examples of proposed screening tests for potential medical conditions include but are not limited to the below:
Not everyone needs to be screened for colon cancer at a young age, but someone with a specific genetic condition or a strong family history may require the evaluation. It is expensive, and somewhat invasive, to do the testing. The test itself may have certain risks.
It is important to strike a balance between selecting the appropriate person to be tested, based on their risk factors and relative likelihood of having the disease, and the utility of the testing available.
Everyone is not tested for every disease. A skilled clinician will understand the pre-test probability of a specific measurement or the likelihood that a test will have an anticipated result.
Screening for specific diseases is targeted to at-risk people. To find and treat a condition in the highest number of people possible, the costs of the testing must be justified and false positives must be avoided.
Positive and Negative Predictive Value
It is appropriate for healthcare providers to consider the risks of a disease within an untested group through the lens of two additional considerations: PPV and NPV.
PPV and NPV, combined with the frequency of a disease in the general population, offer predictions about what a broad-scale screening program might look like.
Sensitivity and Specificity Examples
Some tests are very good at identifying certain diseases and conditions, while others are better at ruling them out. For example:
Summary
Knowing the strengths of different tests is useful for effectively identifying a disease. If a patient might have a life-threatening condition, or their potential illness has a critical window to act, it can be hard to balance the factors of timeliness, accuracy, and cost of testing.
Those who are early in medical training may not have developed the experience and skill to select appropriate testing, and this can lead to a reactive urge to over-test in order to not miss a diagnosis.
Unfortunately, the wrong test may lead down a path toward additional testing or even improper treatment. Skilled healthcare providers will be able to help a patient in need judiciously select the appropriate testing. As medical science advances, we will be able to identify risk factors and personalize testing to further expedite the process of diagnosis and optimal treatment.
6 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.John Hopkins Medicine.Screening tests for common diseases.Shreffler J, Huecker MR.Diagnostic testing accuracy: sensitivity, specificity, predictive values and likelihood ratios.In:StatPearls. StatPearls Publishing; 2024.National Institute of Cancer.How cancer is diagnosed.Queen’s University.The concept of a gold standard.Zeeshan M, Salam B, Khalid QSB, Alam S, Sayani R.Diagnostic accuracy of digital mammography in the detection of breast cancer.Cureus. 2018;10(4):e2448. doi:10.7759/cureus.2448Thewjitcharoen Y, Jones Elizabeth A, Butadej S, et al.Performance of HbA1c versus oral glucose tolerance test (OGTT) as a screening tool to diagnose dysglycemic status in high-risk Thai patients.BMC Endocr Disord. 2019;19(1):23. doi:10.1186/s12902-019-0339-6
6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.John Hopkins Medicine.Screening tests for common diseases.Shreffler J, Huecker MR.Diagnostic testing accuracy: sensitivity, specificity, predictive values and likelihood ratios.In:StatPearls. StatPearls Publishing; 2024.National Institute of Cancer.How cancer is diagnosed.Queen’s University.The concept of a gold standard.Zeeshan M, Salam B, Khalid QSB, Alam S, Sayani R.Diagnostic accuracy of digital mammography in the detection of breast cancer.Cureus. 2018;10(4):e2448. doi:10.7759/cureus.2448Thewjitcharoen Y, Jones Elizabeth A, Butadej S, et al.Performance of HbA1c versus oral glucose tolerance test (OGTT) as a screening tool to diagnose dysglycemic status in high-risk Thai patients.BMC Endocr Disord. 2019;19(1):23. doi:10.1186/s12902-019-0339-6
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
John Hopkins Medicine.Screening tests for common diseases.Shreffler J, Huecker MR.Diagnostic testing accuracy: sensitivity, specificity, predictive values and likelihood ratios.In:StatPearls. StatPearls Publishing; 2024.National Institute of Cancer.How cancer is diagnosed.Queen’s University.The concept of a gold standard.Zeeshan M, Salam B, Khalid QSB, Alam S, Sayani R.Diagnostic accuracy of digital mammography in the detection of breast cancer.Cureus. 2018;10(4):e2448. doi:10.7759/cureus.2448Thewjitcharoen Y, Jones Elizabeth A, Butadej S, et al.Performance of HbA1c versus oral glucose tolerance test (OGTT) as a screening tool to diagnose dysglycemic status in high-risk Thai patients.BMC Endocr Disord. 2019;19(1):23. doi:10.1186/s12902-019-0339-6
John Hopkins Medicine.Screening tests for common diseases.
Shreffler J, Huecker MR.Diagnostic testing accuracy: sensitivity, specificity, predictive values and likelihood ratios.In:StatPearls. StatPearls Publishing; 2024.
National Institute of Cancer.How cancer is diagnosed.
Queen’s University.The concept of a gold standard.
Zeeshan M, Salam B, Khalid QSB, Alam S, Sayani R.Diagnostic accuracy of digital mammography in the detection of breast cancer.Cureus. 2018;10(4):e2448. doi:10.7759/cureus.2448
Thewjitcharoen Y, Jones Elizabeth A, Butadej S, et al.Performance of HbA1c versus oral glucose tolerance test (OGTT) as a screening tool to diagnose dysglycemic status in high-risk Thai patients.BMC Endocr Disord. 2019;19(1):23. doi:10.1186/s12902-019-0339-6
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