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#1
07-13-2012
 USMLE Forums Guru Steps History: 1+CK+CS Posts: 433 Threads: 52 Thanked 387 Times in 148 Posts Reputation: 397
Calculating the Incidence Rate!

can anyone plz confirm my explanation to the answer

in a survey, 10,000 iv drug abusers in springfield, 1000 infected with hep C and 500 with hep B. During a two year follow up , 200 with hep c and 100 with hep B died. Also, 200 IV abusers acquire C and 50 acquire B.

which of the following is the best estimate of the annual incidence of hep C infection in the IV abusers in springfield?

as far as i know, 9000 is coz of 10000-already cases (1000) = 9000
and about the 100, is it coz if 200 died and 200 acquired in 2 years so we divide the 200 acquired by 2 to give us and estimate of 100 per year??
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#2
07-13-2012
 USMLE Forums Guru Steps History: Not yet Posts: 375 Threads: 17 Thanked 131 Times in 81 Posts Reputation: 147

This a nice tricky question.
Ignore the whole question...Just look at the last line. 200 new in the 2 follow up years...mean 100 a year. And you are also right about the denominator.

I hate Biostats.

I could be wrong too .......:co nfused:
#3
07-13-2012
 USMLE Forums Guru Steps History: 1+CK+CS Posts: 433 Threads: 52 Thanked 387 Times in 148 Posts Reputation: 397

Quote:
 Originally Posted by Doc4Step1 This a nice tricky question. Ignore the whole question...Just look at the last line.200 new in the 2 follow up years...mean 100 a year.And you are also right about the denominator. I hate Biostats. I could be wrong too .......:co nfused:
Don't worry this is the key answer, i just wanted the correct explanation thanks
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