USMLE forum
 
USMLE Forum
Step 1
Step 2 CK
Step 2 CS
Matching & Residency
Step 3
Classifieds
 
Archives
 
 
  <<   < *  Step 3   *  >   >>  

* Biostat :).
 #854848  
  aricept123 - 10/05/18 22:03
 
  A phase 2, multicenter trial was conducted to determine the efficacy of a new vaccine for prevention of HIV infection. The study enrolled 4000 subjects, aged 20 to 65 years. Of these subjects, 2100 were men and 1900 were women; 2500 were white, 1000 were African American, 300 were Hispanic, and 200 were Asian/Pacific Islanders. Results of the trial showed no overall benefit of the vaccine. However, post hoc analysis disclosed a small but statistically significant vaccine protection among African American subjects. Which of the following is the most accurate rationale for questioning the validity of efficacy analysis of the HIV vaccine among the African American study subjects?

(A) Allocation bias favored African American subjects
(B) HIV infection is more prevalent among African American populations
(C) The study was not blinded
(D) There was a Type II error
(E) Vaccine response among African American subjects was not the primary outcome measure
 
Report Abuse

 
 

* Re:Biostat :).
#3373276
  cardio69 - 10/06/18 18:15
 
  Post Hoc... Try to complete rest, that u can gain something from it.  
Report Abuse

* Re:Biostat :).
#3373278
  aricept123 - 10/06/18 20:37
 
  I don't get it :(  
Report Abuse

* Re:Biostat :).
#3373308
  cardio69 - 10/07/18 17:55
 
  That's what I want to hear...

What outcome should match 4d Q asking you (measure type)?
- 1ry
- 2nry
- Other prespecify
- Post Hoc

It seems the pic painted in randomization that end into the primary outcome. 2ndray & Hoc analysis look at different outcomes/or relationships that were not thought of during planning of the trial more of perhaps potential flows in 1ry studies (i.e. biases, confounders, loss of follow up…) that not painted here. Their study has limitations 1st, preach. But the overall small but statistical vaccine protecting among AA subjects. So, you simply accurate rational 4Q validity of efficacy analysis of HIV vaccine among AA subject -> NOT the 1ry measure…


Fin
(:
 
Report Abuse

* Re:Biostat :).
#3373487
  aricept123 - 10/11/18 13:35
 
  got it!. Thanks :)!  
Report Abuse

* Re:Biostat :).
#3373496
  cardio69 - 10/11/18 18:31
 
  Welcome.  
Report Abuse

          Page 1 of 1          

[<<First]   [<Prev]  ... Message ...  [Next >]   [Last >>]

 
Logon to post a new Message/Reply
 
 
 
 

 

 

Google
  Web USMLEforum.com
 

Step 1 Step 2 CK Step 2 CS Matching & Residency Step 3 Classifieds
LoginUSMLE LinksHome