USMLE Step 1 Question of the Day
Quiz-summary
0 of 1 questions completed
Questions:
- 1
Information
USMLE Step 1 Questions
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
Results
Time has elapsed
You have reached 0 of 0 points, (0)
Categories
- Biostatistics 0%
-
Question:
A 35 year old woman presents with recent onset constitutional symptoms, including daily fevers, a 5 kg weight loss, and fatigue. She also has been “coughing up blood” and has had occasional sinus headaches and runny nose. An initial chest X-ray shows cavitations. A PPD is read as negative. You suspect the patient may have Wegener’s granulomatosis, and want to test her cANCA level. You tell her that in general the probability a positive test result means that she actually has the disease are most dependent on
Correct Answer: C. The prevalence of Wegener’s in people with her symptoms
The probability that a patient is truly positive for a disease given a positive test result is known as the positive predictive value (PPV). The PPV changes with the prevalence of the disease in a population. When the disease is very prevalent, the PPV will increase; when it is very uncommon, it will decrease. The opposite is true of the negative predictive value.
Sensitivity and specificity of a test are fixed test characteristics that are not affected by disease prevalence.
The other choices are not relevant for this disease and do not answer the question.
- 1
- Answered
- Review
-
Question 1 of 1
1. Question
Category: BiostatisticsA 35 year old woman presents with recent onset constitutional symptoms, including daily fevers, a 5 kg weight loss, and fatigue. She also has been “coughing up blood” and has had occasional sinus headaches and runny nose. An initial chest X-ray shows cavitations. A PPD is read as negative. You suspect the patient may have Wegener’s granulomatosis, and want to test her cANCA level. You tell her that in general the probability a positive test result means that she actually has the disease are most dependent on
Correct
Incorrect