anatomy
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The prevalence of a disease is half as great in town A than it is in town B, but the incidence of the disease is no different in town A than it is in town B. Which of the following best explains these findings?
A) The case fatality rate is twice as high in town A.
B) The duration of the disease is twice as long in town B.
C) The number of new cases in town A is twice as many as those in town B.
D) People in town A use medical care facilities half as often as those in town B.
E) The proportion of asymptomatic cases is twice as much in town B than in town A
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| phuluong2k
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answer B (although A is also reasonable ) but i think prevelence depends on duration of disease
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| Dani_2005
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I'll go with B. Because case fatality rate does not necessarily reflect the ratio between the prevalence in the two towns. I'll give an example here. suppose 100 patients accumulated over 100 days (with an incidence of 1 patient per day). Now suppose that the case fatality is 2 % in town A and 1 % in town B. After 100 day, the prevalence in town A is 98/pop., and in town B is 99/pop. (which is by no means double the prevalence of A). So it is not direct proportional relationship. While the relationship between prevalence and duration of the disease is directly proportional. This equation might help:
Prevalence = incidence * duration * ( 1 - case fatality ratio )
The other choices are clearly wrong.
So I think it is B. - need confirmation though.
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| Moctopod
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Agree with B
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| anatomy
Forum Guru
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i don't know the answer that's why i posted here.
i also think it's "b"
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