What are sensitivity and specificity in disease screening tests?

  

We are exploring sensitivity and specificity this week. This can let you know the limitations of a test for a disease. More and more labs, hospitals, and public health agencies are moving to molecular methods to test for disease, but often for screening tests we use test like EIA or other rapid immunogenic tests.

Your goal:

Don't use plagiarized sources. Get Your Custom Essay on
What are sensitivity and specificity in disease screening tests?
Just from $13/Page
Order Essay

Select a disease
Find the prevalence of that disease in the US
Find a screening test for that disease and the manufacturers reported sensitivity and specificity
Apply that proportion to a random population of 100,000 people
Calculate the predictive positive value and the predictive negative value
Answer the question: Does it make sense to screen for this disease using this test and based on the natural history of the disease why or why not?

Example: How to work the math alone

Disease X occurs at a prevalence of 10 per 100,000 population.
Screening test Y has a sensitivity of 95% and a specificity of 80%.
Step 1:

Disease (+)

Disease (-)

Test (+)

95%

20%

Test (-)

5%

80%

10

999,990

Step 2:

Disease (+)

Disease (-)

Test (+)

9.5

199,998

Test (-)

.5

799,992

10

999,990

From this point, you can easily calculate the predictive positive and the predictive negative values. The real challenge is going to look at the natural history of the disease, cost of the test, treatment of the disease and determine if screening is appropriate. If it is appropriate or not, you have to provide researched justification as to why it is not or is and if there are certain groups it would be best to screen or prioritize why or why not.
All research should be cited and appropriately supported.
The initial post must be between 350 – 500 words.

Introduction:

The diagnostic tests for diseases, commonly known as screening tests, are an essential tool in detecting the prevalence of a particular disease. Sensitivity and specificity are two factors that help understand the limitations of screening tests for a disease. As new tests are developed in the health industry, it is essential to analyze the sensitivity and specificity of these tests to determine their efficacy in detecting diseases. In this exercise, we aim to evaluate the usefulness of a screening test for a particular disease and whether screening for this disease using the test is appropriate.

Description:

In recent times, there has been an increasing trend toward using molecular methods to test for diseases. However, for screening tests, rapid immunologic tests like EIAs are often used. In this exercise, we aim to select a disease, determine the prevalence of that disease in the US, and then evaluate the efficacy of a test – sensitivity and specificity. We will then apply these proportions to a random population of 100,000 people and calculate the predictive positive and negative values to answer the vital question of whether it makes sense to screen for that disease using that test.

To understand the importance of screening tests, we need to consider their efficacy in detecting diseases. The tests’ efficacy is usually measured by determining their sensitivity and specificity. A test with high sensitivity is useful in detecting diseases in a population with a high prevalence of the disease. In contrast, a test with high specificity is essential in identifying people who do not have the disease accurately. Therefore, sensitivity is the proportion of true positives, and specificity is the proportion of true negatives determined by the test.

A critical aspect of this exercise is the natural history of the disease, the cost of the test, and the treatment options available. These factors play a significant role in deciding whether to screen a population for that disease. This exercise aims to provide a reasoned justification as to why screening for the disease is appropriate and in what groups.

In conclusion, this exercise underlines the importance of screening tests to detect diseases, evaluate sensitivity and specificity, and determine if screening a particular population is appropriate for the disease under study. The natural history of the disease, cost-effectiveness, and treatment options must be taken into account to arrive at a decision whether screening with a particular test is appropriate or not. Thus, this exercise is a useful tool in understanding the efficacy of screening tests and their role in detecting diseases amongst different population groups.

Heading: Understanding the Importance of Sensitivity and Specificity in Determining the Efficacy of Screening Tests

Objectives:
– To understand the concepts of sensitivity and specificity in diagnostic tests
– To be able to calculate predictive positive and negative values based on the sensitivity and specificity of a test
– To evaluate the appropriateness of using a screening test for a particular disease based on the natural history of the disease and other factors such as cost and treatment options
– To provide researched justification for the decision to screen or not to screen for a particular disease

Learning Outcomes:
– Students will be able to define sensitivity and specificity and provide examples of their importance in diagnostic testing
– Students will be able to apply the principles of sensitivity and specificity to calculate predictive positive and negative values for a given disease and screening test
– Students will be able to interpret the results of the predictive values and make a decision on the appropriateness of using the screening test
– Students will be able to research and justify their decision to screen or not to screen for a particular disease based on the natural history of the disease, cost of the test, and treatment options

Explanation:
This week’s topic is sensitivity and specificity in diagnostic tests. The objectives listed above are related to this topic and can help students understand the limitations of a test for a particular disease. Students will be asked to select a disease of their choice and calculate the prevalence of that disease in the US. They will then choose a screening test for that disease and find the reported sensitivity and specificity from the manufacturer. Based on this information, students will apply the proportion to a random population of 100,000 people and calculate the predictive positive and negative values.

The focus of this exercise is not only on the math but also on the decision-making process. Students will be asked to analyze the natural history of the disease, cost of the test, and treatment options to determine whether or not it makes sense to screen for that disease using the selected test. The decision should be supported by research with appropriate citations. Students should also consider if there are certain groups that may benefit from screening and prioritize them accordingly.

In conclusion, this exercise will help students understand the importance of sensitivity and specificity in diagnostic tests, calculate predictive values, and make informed decisions regarding the appropriateness of using a screening test for a particular disease. This exercise will also help students develop research and analytical skills to support their decision-making process.

Solution 1:

Disease: Gonorrhea
Prevalence of Gonorrhea in the US: According to the Centers for Disease Control and Prevention (CDC), in the year 2019, there were approximately 616,392 cases of gonorrhea reported in the United States, with a case rate of 189.3 per 100,000 population.

Screening Test: Nucleic acid amplification tests (NAATs) are commonly used to screen for gonorrhea. The Centers for Medicare & Medicaid Services (CMS) has approved several NAAT gonorrhea tests, including Aptima Combo 2® and Xpert® CT/NG. Aptima Combo 2® is manufactured by Hologic Inc. with a reported sensitivity of 96.45% and specificity of 99.55%. Xpert® CT/NG is manufactured by Cepheid Inc. with a reported sensitivity of 95.9% and specificity of 99.3%.

Application of Proportions to a Random Population of 100,000 People:
Let’s say we apply the proportion of Aptima Combo 2® to the random population of 100,000 people. We’ll get the following chart.

Disease (+) Disease (-)
Test (+) 2,361 44
Test (-) 99 97,496

Predictive Positive Value (PPV) and Predictive Negative Value (NPV):
PPV = True Positives / (True Positives + False Positives) = 2,361 / (2,361 + 44) = 98.2%
NPV = True Negatives / (True Negatives + False Negatives) = 97,496 / (97,496 + 99) = 99.9%

Does it make sense to screen for Gonorrhea using Aptima Combo 2®:
Gonorrhea is a sexually transmitted disease with potentially serious complications. Early detection and treatment can prevent the spread of the infection and minimize the risk of complications. The high prevalence rate of Gonorrhea in the US and the high sensitivity and specificity of Aptima Combo 2® test make it a suitable screening test for the disease. Therefore, it makes sense to screen for Gonorrhea using Aptima Combo 2®.

Solution 2:

Disease: Lung cancer
Prevalence of Lung cancer in the US: According to the American Cancer Society, it is estimated that there will be around 235,760 new cases of lung cancer diagnosed in the United States in 2021.

Screening Test: Low-Dose Computed Tomography (LDCT) is commonly used to screen for lung cancer. LDCT uses low doses of radiation to take detailed images of the lungs. It is recommended for people who have a high risk of developing lung cancer due to smoking history or other risk factors. Several manufacturers make LDCT machines, including Toshiba, Siemens, and Phillips.

Application of Proportions to a Random Population of 100,000 People:
As LDCT is not used for screening in the general population but only for high-risk individuals, it is not appropriate to apply the proportions to a random population of 100,000 people.

Does it make sense to screen for Lung cancer using LDCT:
While LDCT is a highly sensitive test for detecting lung cancer, it is not recommended for use in the general population due to its high cost, radiation exposure, and potential harm from overdiagnosis and overtreatment of benign nodules. LDCT is only recommended for high-risk individuals, such as current and former smokers, who meet specific criteria. Based on the natural history of the disease and the potential harms of screening with LDCT, it does not make sense to screen for lung cancer using LDCT in the general population but only for high-risk individuals.

Suggested Resources/Books:

1. Screening for Disease: Principles and Guidelines. By Kathleen N. Lohr
2. Understanding Diagnostic Tests in the Childbearing Year. By Anne Frye
3. Clinical Epidemiology: The Essentials. By Robert H. Fletcher, Suzanne W. Fletcher, and Grant S. Fletcher
4. Evidence-Based Medicine: How to Practice and Teach EBM. By Sharon E. Straus, Paul Glasziou, and W. Scott Richardson

Similar Asked Questions:

1. What is the significance of sensitivity and specificity in disease screening tests?
2. How do you calculate the positive and negative predictive values of a screening test?
3. What are some limitations of using rapid immunogenic tests over molecular methods in disease screening?
4. Why is it important to consider the natural history of a disease when deciding to screen for it?
5. How do societal factors, such as cost and treatment availability, influence the decision to screen for a disease?

Screening for Tuberculosis: Is it Worth it?

Tuberculosis (TB) is a bacterial infection that primarily affects the lungs. In the United States, the prevalence of TB is relatively low, with only 8,917 cases reported in 2020, according to the Centers for Disease Control and Prevention (CDC). The standard screening test for TB is the tuberculin skin test (TST), also called the Mantoux test. The manufacturer’s reported sensitivity and specificity for the TST vary depending on the population being tested. However, the American College of Chest Physicians currently recommends using a cutoff of 10 mm or greater as a positive result. The sensitivity of the TST in this population is approximately 77%, while the specificity is around 98%.

Using these numbers, we can calculate the predictive positive and predictive negative values of the TST in a random population of 100,000. Out of 100,000 people, we would expect approximately 78 individuals to test positive for TB based on the TST. Of these 78 individuals, only 2 will not actually have the disease, giving us a positive predictive value (PPV) of 97.4%. On the other hand, we would expect roughly 9,908 individuals to test negative for TB. Of these 9,908, about 198 will actually have the disease, giving us a negative predictive value (NPV) of 98%.

While these results suggest that the TST is a relatively reliable test for screening for TB, it is important to consider the natural history of the disease and other societal factors when deciding whether it is worth it to screen for TB using the TST. TB is a treatable disease, but it requires a long course of antibiotics and close follow-up. As such, screening for TB should only be recommended if there is a high risk of infection and disease transmission within a certain population. This may include individuals working in high-risk professions, such as healthcare or corrections, or individuals with frequent travel to regions with high TB incidence.

Moreover, the cost of the TST may make it prohibitive in some settings. The test requires a trained healthcare provider to administer and interpret, and it must be read within 48-72 hours. In contrast, newer molecular methods for detecting TB, such as the Xpert MTB/RIF assay, offer faster and more accurate diagnosis but often come with a higher cost.

In conclusion, while the TST has been a reliable screening test for TB in certain high-risk populations, it is important to consider the natural history of the disease and the cost and availability of other diagnostic tests before recommending widespread screening. Clinicians should look to organizations such as the CDC and the American Thoracic Society for guidance on screening for TB in their particular patient populations.

Basic features
  • Free title page and bibliography
  • Unlimited revisions
  • Plagiarism-free guarantee
  • Money-back guarantee
  • 24/7 support
On-demand options
  • Writer’s samples
  • Part-by-part delivery
  • Overnight delivery
  • Copies of used sources
  • Expert Proofreading
Paper format
  • 275 words per page
  • 12 pt Arial/Times New Roman
  • Double line spacing
  • Any citation style (APA, MLA, Chicago/Turabian, Harvard)

Our guarantees

Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.

Money-back guarantee

You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.

Read more

Zero-plagiarism guarantee

Each paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.

Read more

Free-revision policy

Thanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.

Read more

Privacy policy

Your email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.

Read more

Fair-cooperation guarantee

By sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.

Read more
× How can I help you?