phuluong2k
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A physiccian interviews an 18 year old female patient who mentions that she has just received a negative syphilis test result from the county health department. She describe her sense of relief at receiving the test result. She discloses that she is a sex worker who "works the stroll" four to five nights a week. She has been " tricking" for the past 18 months. Typically, she has oral or vaginal sex with five to eight customers pernight
For a higher fee, she will have sex without requiring her customer to wear a condom. On the basis of these finding, the physycian is likely to be most concerning with which of the following screening test measures ?
A. Sensitivity
B. Specificity
C. Positive predictive value
D. Negative predictive value
E. Accuracy
Plz give your explanation
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| Springd
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A.
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| phuluong2k
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the answer is Negative predictive value, but there is not an explanation
I think this q is confusing because there is a positve correlation between sensitive & NPV
so may be both A & D are correct ???
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| chemamr
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i thought NPV, but I have no explanation. Biostatistics and epidemiology are weak areas for me.
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| Merih
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In USMLEWORLD BIOSTAT&PREV.MED. MCQS-answers, these are well explained. NPV of the syphilis test is more imp. than sensitivity.it's the factor that determines reliability of the result. UW explains better than me.
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| mdwannabe
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NPV... She just recieved a negative result, but she is still in high-risk setting..therefore..how likely is she to be really Negative in the face of negative result.
Hope this helps.
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| guayoman
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NPV, accuracy and specificity all talk about the probability of the negative result being actually negative. So you could answer any of the 3 options and you would be correct. But, why is NPV the best answer for the Q?
NPV: The proportion of people with a negative screening test result who are well.
Edited by guayoman on 08/17/05 - 04:42 PM
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| guayoman
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This thing is scrambling my post. I canīt edit it!  
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| guayoman
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The thing is IF you knew for a fact that she was NEG then you could use specificity. accuracy is just to complicated to be right answer. HAHA
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| intern_doc
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The answer is NPV
If the stem of the Q give you that the test is NEGATIVE, then you as a physician try to to NPV as a next test to see how accurate the result is.
If the stem of the Q give you POSITIVE (hiV), then you would want to do a PPV
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