Prep for USMLE 
Forum  Resources  New Posts  Register  Login  » 

Author  1 Posts  
Kruno
Forum Newbie Topics: 0 Posts: 11 
An imaginary study involving 650 people was conducted to assess the performance of the stool antigen assay in detecting a helicobacter pylori infection. After collecting all the test results, it was found that 250 people tested positive and 400 people tested negative. If the positive and negative predictive value were 80% and 75%, respectively, then what proportion of people with the infection were identified by the test? (A) 300/650 (B) 200/250 (C) 200/300 (D) 200/650 How would the sensitivity of the test change if the number of positive tests was higher? (A) It would increase (B) It depends on the prevalence (C) Not enough information is provided (D) It would decrease What would the sensitivity of the test be if 10 people with the condition did not test negative? (A) 200/310 (B) 210/300 (C) 210/310 (D) 200/300 The answers and explanations can be found on youtube via this link... https://www.youtube.com/watch?v=2fe_kjH_bbk  
Similar forum topics Sequential loss of hormones Sequential Questions & Lab Values Goljan part 1 or both part 1 and 2 for step 1  Related resources Conrad Fischer's Internal Medicine Question Book 