An epidemiological investigation was begun on July 1, 2000 among a population of 1,000 individuals. Three individuals were found to have leukemia on July 1st. During
the ten-year follow-up period, five new cases of leukemia were diagnosed. Among the eight leukemia cases, four deaths occurred during the ten-year follow-up period.
Two additional individuals, neither of whom had leukemia, were lost to follow-up at some point during follow-up. None of the remaining 990 study participants became
ill, died, or were lost to follow-up during the follow-up period.
The diagram below indicates the experience of the 10 study participants, using the following symbols:
*
:case recognition (diagnosis of leukemia)
*<
:onset of leukemia was prior to start of study period
—-
:observation period during follow-up
X
:status at termination of observation (i.e., alive, dead, lost)
case
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
1
—
–*–
—–
—–
—–
—–
—–
—–
—–
—–
–X
alive
2
—
——
—–
–*–
—–
—–
—–
—–
—–
—–
–X
alive
3
*<–
——
——
—–
—–
—–
—–
—–
–X
dead
4
—
——
—–
—–
–X
lost
5
—
——
—–
—–
—–
—–
–*–
–X
dead
6
—
——
—–
—–
—–
—–
—–
—–
—–
–*–
–X
alive
7
—
–*–
—–
—–
–X
dead
8
*<–
——
——
—–
—–
—–
—–
—–
—–
—–
—–
–X
alive
9
—
——
—–
—–
—–
—–
—–
–X
lost
10
*<–
——
——
–X
dead
· What was the prevalence of leukemia on January 1, 2005?
· What was the cumulative incidence of leukemia during the 10-year follow-up period?
· What was the incidence rate of leukemia during the 10-year follow-up period?
· What was the case fatality rate during the 10-year follow-up period?
Mod 3
Question 1
For this problem, note the following chart:
Age Group
(in years)
% of Population in Age Group
Influenza Rate per 1,000 person-years
CITY A
CITY B
CITY C
Massachusetts
CITY A
CITY B
CITY C
YOUNG
40%