Biostat Questions Thread for Step 1

[MudPhud20XX]

---

Members don't see this ad.

Hi all, for those of you who are in MS2 and preparing for the board next year, I think biostat is one of the subjects that we often overlook. I would like to open a thread where we put all the biostat questions together, so that we feel confident about this subject. So I will begin. Please bear with me even though you feel like the questions are easy. Thank you very much for your help. So here are my questions.

In a survey of 10,000 IV drug abusers in town X, 1,000 turn out to be infected with hep C and 500 infected with hep B. During two years of follow-up, 200 pts with hep C infection and 100 pts with hep B infection die. Also, during follow-up, 200 IV drug abusers acquire hep C and 50 acquire hep B. Which of the following is the best estimate of the annual incidence of hep C infection in IV drug abusers in town X?

A. 1,000/10,000
B. 1,100/10,000
C. 100/10,000
D. 100/9,000
E. 100/9,800

In a city having a population 1,000,000 there are 300,000 women of childrenbearing age. The following statistics are reported for the city in the year 2000:

Fetal deaths: 200
Live births: 5,000
Maternal deaths: 70

Which of the following is the best estimate of the maternal mortality rate in the city in the year 2000?

A. 70/1,000,000
B. 70/300,000
C. 70/5,000
D. 70/5,200

So what is the role of fetal deaths here??? Should it be considered into the mortality rate?

 

[worldbeater]

Incidence is new cases, prevalence is all cases. So you would take the incidence of Hep C and put it over total cases, which would make it A) 1,000/10,000

Second question, don't know the MMR rate off the top of my head, but I am guessing it would be maternal deaths/child bearing women, which would make it B) 70/300,000. I don't think fetal deaths would be involved.

 

[pavel13]

Great thread, please keep up the questions!

Biostats, although just a few questions, could very well be the difference of +/- around 5 points on your score. They're probably not very hard either so it could be a very easy 5 points!

 

[MudPhud20XX]

Incidence is new cases, prevalence is all cases. So you would take the incidence of Hep C and put it over total cases, which would make it A) 1,000/10,000

Second question, don't know the MMR rate off the top of my head, but I am guessing it would be maternal deaths/child bearing women, which would make it B) 70/300,000. I don't think fetal deaths would be involved.

For the first Hep C question, that's what I thought, but the answer is D. Does anyone have an idea?

I got the 2nd question wrong too. The answer is actually C. Can anyone explain this?

 

[MudPhud20XX]

Great thread, please keep up the questions!

Biostats, although just a few questions, could very well be the difference of +/- around 5 points on your score. They're probably not very hard either so it could be a very easy 5 points!

100% agree with you. I will do so. I am also posting bio q. With all the MS2 stuff going on little bit of questions eventually will help.

An observational study in diabetic assesses the role of an increased plasma fibrinogen level on the risk of cardiac events. 130 diabetic pts are followed for 5 years to assess for the development of acute coronary syndrome. In a group of 60 pts with a normal baseline plasma fibrinogen level, 20 develop acute coronary syndrome and 40 do not. In a group of 70 pts with a high baseline plasma fibrinogen level, 40 develop acute coronary syndrome and 30 do not. Which of the following is the best estimate of relative risk in pts with a high baseline plasma fibrinogen level compared to pts with a normal baseline plasma fibrinogen level?

A. (40/30)/(20/40)
B. (40*40)/(20*30)
C. (40*70)/(20*60)
D. (40/70)/(20/60)
E. (40/60)/(20/70)