Welcome to NP Certification Q&A presented by Fitzgerald Health Education Associates. This podcast is for NP students studying to pass their NP certification exam. Getting to the correct test answers means breaking down the exam questions themselves. Leading NP expert Dr. Margaret Fitzgerald shares her knowledge and experience to help you dissect the anatomy of a test question so you can better understand how to arrive at the correct test answer. So, if you're ready, let's jump right in.
Which of the following applies when considering issues in clinical testing for a given target disease?
A false negative result identifies a person with the target disease. A true positive result identifies a person with the target disease. A true negative result allows for the patient and clinician to discuss treatment options for the target disease. A false positive result supports a patient and clinician discussion on the impact of the target disease on the patient's overall health.
The correct answer here is: B. A true positive result identifies the person with the target disease.
Where should you start? This is a question that would likely come under the larger umbrella of professional issues. It's a question that raises issues of test sensitivity and specificity, and really impacts a number of issues in our practice. A mathematically calculated, a mathematically derived calculation, sensitivity and specificity describe the accuracy of a given diagnostic test.
Let's take a look at some of these definitions. A test’s sensitivity contributes to the diagnostic study's true positive rate. In other words, when a person with a given disease is correctly identified by the test. An example would be an 18-year-old symptomatic teen with an exudative pharyngitis presents and has a positive rapid strep screen. His true positive result allows for appropriate antimicrobial therapy to be initiated.
So, it's kind of a really simple example, but a really helpful example. A test specificity contributes to the diagnostic study’s true negative rate. In other words, when a person without the disease is correctly identified and the target disease is ruled out. Another example would be an 18-year-old who presents with clear nasal discharge, a dry cough, and a mildly red pharynx, and has a negative rapid strep screen.
So, in other words, strep throat has been pretty much ruled out here. This allows the clinician to discuss with the patient that strep is not the cause of this sore throat or the runny nose, and antimicrobial therapy is not needed.
When discussing true positive and true negative results, one must also consider false positive and false negative results. In a false positive result, a person who does not have the target disease is inaccurately identified as having the condition. Often additional testing is needed to rule in/rule out the condition. A simple way to remember this is that a false positive result costs time, effort, including diagnostics that are done subsequently to the initial false positive test, and worry, to rule out the target condition. And then at the end of the evaluation, the patient, if you will, is restored to health. In other words, the condition has finally been appropriately ruled out. In a false negative result, a person with the target disease is not identified. A simple way to remember this is that with a false negative result, the opportunity to intervene in the target condition is missed.
So, with this in mind, let's take a look at the question and the potential answers. Which of the following applies when considering issues of clinical testing in a given target disease? A false negative result identifies the person with the target disease. This is of course, incorrect. The cost of that false negative result is that a person with a given condition is not identified and the opportunity to intervene is missed.
A true positive result identifies the person with the target disease. This is of course correct and the person with the disease is now identified, and the clinician and patients can proceed to discuss next steps and possible treatment options. But let's take a look at both C and D, even though we already have our correct answer.
C. A true negative result allows for the patient and clinician to discuss treatment options for the target disease. Well, this is incorrect. As mentioned, the true negative result implies that the patient does not have the target disease.
Option D. A false positive result supports the patient and clinician having a discussion on the impact of the target disease on the patient's overall health. That's also incorrect because the way this is worded, it implies that a false positive means the person has the condition and with a false positive result, the patient does not have the disease but is falsely identified.
Key takeaway: As a nurse practitioner, you're now also a diagnostician. Appreciating test sensitivity and specificity, as well as knowing how to discuss test results with patients, is critical to your new practice and your new role.
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