A 68-year-old man presents to the office for his annual physical examination. He has no current complaints. Past medical history is unremarkable. He reports a 30-pack-year smoking history but no alcohol or drug use. Review of systems is only remarkable for thicker mucous production that is worse in the morning when he coughs. A non-contrast CT scan of his chest is performed, and the doctor informs him that a 2 cm nodule has been identified in his upper lobe of the left lung near the left main bronchus and that further testing is required to rule out malignancy. The patient is surprised by this news since he has never experienced any alarming symptoms. The doctor informs him that lung cancers don’t usually present with symptoms until late in the course of the disease. The doctor says that sometimes it may take several years before it becomes severe enough to cause symptoms, which is why patients with risk factors for developing lung cancer are screened at an earlier age than the general public. Which of the following concepts is being described by the doctor to this patient?
AConfounding bias
BLatent period
CInduction period
DLead time bias
ESurveillance bias
A student health coordinator plans on leading a campus-wide HIV screening program that will be free for the entire undergraduate student body. The goal is to capture as many correct HIV diagnoses as possible with the fewest false positives. The coordinator consults with the hospital to see which tests are available to use for this program. Test A has a sensitivity of 0.92 and a specificity of 0.99. Test B has a sensitivity of 0.95 and a specificity of 0.96. Test C has a sensitivity of 0.98 and a specificity of 0.93. Which of the following testing schemes should the coordinator pursue?
ATest A on the entire student body followed by Test B on those who are positive
BTest A on the entire student body followed by Test C on those who are positive
CTest C on the entire student body followed by Test B on those who are positive
DTest C on the entire student body followed by Test A on those who are positive
ETest B on the entire student body followed by Test A on those who are positive
A pharmaceutical corporation is developing a research study to evaluate a novel blood test to screen for breast cancer. They enrolled 800 patients in the study, half of which have breast cancer. The remaining enrolled patients are age-matched controls who do not have the disease. Of those in the diseased arm, 330 are found positive for the test. Of the patients in the control arm, only 30 are found positive. What is this test’s sensitivity?
A330 / (330 + 30)
B330 / (330 + 70)
C370 / (30 + 370)
D370 / (70 + 370)
E330 / (400 + 400)
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