Epidemiology Questions Homework

Consider a group of 1,000 newborn infants. 100 infants were born with serious birth defects and 20 of these 100 died during the first year of life. 90 of the 900 remaining infants without any birth defects also died during the first year of life.

Calculate the prevalence of serious defects in this population at the time of birth.

Calculate the overall curnulative incidence of mortality in this population.

Calculate the currulative incidence difference in mortality between infants born with serious birth defects and without.

State in words your interpretation of the cumulative incidence difference calculated in part c.

QUESTION 2 1. A population of 1,000 people is monitored for a year for the development of measles. No one has measles at the start of the investigation. Thirty people develop measles on June 30 and twenty people develop measles on September 30. Eight people are lost to follow-up on March 31 and twenty-four people are lost to follow-up on November 30. None of those lost to follow-up had developed measles prior to becorning lost. Assume that you can only get measles once.

What is the currulative incidence of measles in this population?

What is the incidence rate of measles?

What is the prevalence of measles on July 1?

QUESTION 3 1. 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 lst. 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 leukernia, 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) *< conset of leukemia was prior to start of study period tobservation 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 alive 2 alive 3 -X dead 4 lost 5 dead 6 alive 7 dead 8 alive 9 lost 10 X dead

What was the prevalence of leukemia on January 1, 2005?

What was the curnulative 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?