Friday, 11 January 2013

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Practice Question #9

I know! I know! We absolutely hate numbers, formulas, diagrams, and biostats. This is exactly why the following question exists. To prepare you for the USMLE and Life!

A 23 year old woman comes to your clinic with a positive HIV test. She tells you that she read about the screening test they performed on her. She tells you that it was based on 1,000,000 patients, of which 700,000 had HIV. She also tells you that of those, only 600,000 had a positive result. She gulps and says that the test was also positive in 100,000 of the non-diseased patients. She is very nervous and fidgety, and wishes to know which of the following would be more useful to her:

1. Positive Predictive Value
2. Sensitivity
3. Specificity
4. Negative Predictive Value