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Free notes, MCQs, tables & flowcharts for USMLE Step 2 CK Biostatistics
A 35-year-old woman with a medical history significant for asthma, hypertension, and occasional IV drug use comes to the emergency department with fever. On physical exam, there are findings depicted in figure A, for which the patient cannot account. What test will be most helpful to establish the diagnosis?
AEchocardiography
BElectrocardiogram (EKG)
CChest X-ray
DCT pulmonary angiography
EPulmonary function tests
A 32-year-old man comes to the physician for a follow-up examination 1 week after being admitted to the hospital for oral candidiasis and esophagitis. His CD4+ T lymphocyte count is 180 cells/μL. An HIV antibody test is positive. Genotypic resistance assay shows the virus to be susceptible to all antiretroviral therapy regimens and therapy with dolutegravir, tenofovir, and emtricitabine is initiated. Which of the following sets of laboratory findings would be most likely on follow-up evaluation 3 months later? $$$ CD4 +/CD8 ratio %%% HIV RNA %%% HIV antibody test $$$
A↓ ↓ negative
B↑ ↑ negative
C↓ ↑ negative
D↑ ↓ positive
E↓ ↑ positive
A 36-year-old female presents to clinic inquiring about the meaning of a previous negative test result from a new HIV screening test. The efficacy of this new screening test for HIV has been assessed by comparison against existing gold standard detection of HIV RNA via PCR. The study includes 1000 patients, with 850 HIV-negative patients (by PCR) receiving a negative test result, 30 HIV-negative patients receiving a positive test result, 100 HIV positive patients receiving a positive test result, and 20 HIV positive patients receiving a negative test result. Which of the following is most likely to increase the negative predictive value for this test?
ADecreased prevalence of HIV in the tested population
BIncreased prevalence of HIV in the tested population
CIncreased number of false positive test results
DIncreased number of false negative test results
EDecreased number of false positive test results
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