Explain the importance of validity and reliability in diagnostic testing or research. Describe how validity relates to sensitivity and specificity in diagnostic testing. Identify a health screen specific to a diagnostic test that is currently being debated regarding its use, recommended ages, or frequency, and discuss how validity and reliability play into this debate. What other factors should you consider when you assess the recommendations for a diagnostic test or screen? PUB 540 Principles of epidemiology Topic 2 DQ 2.
Topic 2 DQ 2
Validity is crucial in research and testing because it ensures that no external forces like bias are skewing the results and it supports generalizability, application to real-life settings, and application in other contexts (Andrade, 2018). Simply put, validity measures how well a research or diagnostic testing instrument is performing its intended task (Andrade, 2018). This concept relates to sensitivity and specificity because it allows researchers or diagnosing providers to describe a tool’s ability to produce sensitive and specific results (Andrade, 2018). Reliability is also incredibly important because it relates to consistency in the methods used to obtain such research and testing results, furthermore allowing for the calculation of specificity (Andrade, 2018). PUB 540 Principles of epidemiology Topic 2 DQ 2.
One example where validity and reliability may become debatable is in the use of genetic testing as a means of a diagnostic approach (Burke, 2014). For example, a genetic disease called multiple endocrine neoplasia type 2 (MEN2), can benefit greatly from genetic testing where sensitivity can be seen at 95% to 98% and specificity approaches 100% (Burke, 2014). However, this positive predictive value of the genetic testing in this case is seen to be strongly effected by how prevalent the disease is in the population being tested (Burke, 2014). This creates a low positive predictive value when the same genetic testing is conducted amongst a population with little likelihood of the same disease (Burke, 2014). Furthermore, other forms of genetic testing typically have low sensitivity due to limitations of causative mutations that the test is able to identify (Burke, 2014). Because of these issues and as with all other diagnostic testing, the genetic testing results should always be compared against the “gold standard” method for a particular diagnosis (Burke, 2014). A definitive diagnosis should always be based on a combination of new medical data and well-trusted standards (Burke, 2014). PUB 540 Principles of epidemiology Topic 2 DQ 2.
Andrade, C. (2018). Internal, external, and ecological validity in research design, conduct, and evaluation. Indian journal of psychological medicine, 40(5), 498.
Burke, W. (2014). Genetic tests: clinical validity and clinical utility. Current protocols in human genetics, 81(1), 9-15.
Topic 2 DQ 2
When using a test to distinguish between individuals with normal and abnormal results, it is imperative to understand how characteristics of the disease are distributed in varying populations (Celentano & Szlko, 2019). This is why validity and reliability are so important to the success of diagnostic testing. The validity of a test is the ability to differentiate between those that have a disease and those who do not (Celentano & Szlko, 2019). The reliability of a test indicates the extent to which it is without bias and ensures dependable measurement across time and the various items of the tools given in the research (Bajpai & Bajpai, 2013). PUB 540 Principles of epidemiology Topic 2 DQ 2.
There are two key factors to validity: (1) sensitivity of the test and (2) specificity of the test (Celentano & Szlko, 2019). The sensitivity of the test is the ability to determine who has the disease PUB 540 Principles of epidemiology Topic 2 DQ 2. The specificity of the test is the ability to determine who does not have the disease (Celentano & Szlko, 2019).
A health screen that is currently being debated is a breast exam for women, specifically a mammogram to screen for breast cancer. Young women experience a breast exam at routine women appointments, but the mammogram is not performed until the age of 45 (Pratt, 2018). New research suggests that women with specific risk factors should begin breast screenings at the age of 30, but some experts say it may not be effective for women of this age group (Pratt, 2018).
Validity and reliability play into this debate because it is important to know what age group of women are affected are which are not. Only then will experts be able to determine whether or not mammograms will prove to be beneficial at a younger age.
Other factors that should be considered are the health risks and drawbacks associated with the test itself. One large drawback in mammography screening is breast cancer overdiagnosis and overtreatment (Kresser, 2017). For this example, it is critical for research experts to take this factor into consideration before determining whether or not to lower the age for mammograms PUB 540 Principles of epidemiology Topic 2 DQ 2.
Bajpai, S. & Bajpai, R. (2013). Goodness of Measurement: Reliability and Validity. Retrieved from https://www.ejmanager.com/mnstemps/67/67-1380953319.pdf
Celentano, D.D. & Szklo, M. (2019). Gordis Epidemiology (6th Ed). Philadelphia, PA: Elsevier Inc.
Kresser, C. (2017). The Downside of Mammograms. Retrieved from https://kresserinstitute.com/the-downside-of-mammograms/
Pratt, E. (2018). Should Some Women Get Mammograms at 30? Retrieved from https://www.healthline.com/health-news/some-women-should-have-mammograms-starting-at-age-30 PUB 540 Principles of epidemiology Topic 2 DQ 2