Question

1.A prevalence survey conducted from January 1 through December 31, 2014 identified 3000 cases of leukemia in a city of 2 million persons. The incidence rate of leukemia in this population is 6/10,000 persons each year. 1. What percent of the 3000 cases were newly diagnosed in 2014?

2. What would be the effect on age-specific incidence rates of leukemia if women with children were excluded from the denominator of the calculations, assuming that there are some women in each age group that have children? (Would they increase, decrease, stay the same, increase in older groups, increase in younger groups, or something else?)

The population of the city of Toronto on June 30, 2015 = 248,000

Number of new active cases of measles in Toronto occurring in 2015 = 16

Number of active measles cases according to the city register on December 31, 2015 = 355

The incidence rate of active cases of measles in Toronto for the year 2015 was:

The prevalence rate of active cases of measles as of December 31, 2015 was:

In a European country with a population of 10 million people, 40,000 deaths occurred during the year ending December 31, 2012. These included 20,000 deaths from cholera in 100,000 people who were sick with cholera.

What was the cause-specific mortality rate from cholera in 2012? What does this number mean (i.e. how can it be interpreted)?

What was the case-fatality from cholera in 2012? What does this number mean (i.e. how can it be interpreted)?

The mortality rate from disease X in city A is 60/100,000 in persons 50+ years old. The mortality rate from the same disease in city B is 120/100,000 in persons 50+ years old.

Is the inference correct that disease X is two times more prevalent in persons 50+ years old in city B than it is in persons 50+ years old in city A? Why or why not?

In 2000, there were 65,000 deaths due to lung disease in cigarette smokers aged 20-64 years. The expected number of deaths among cigarette smokers based on age-specific death rates from lung diseases in all females aged 20-64 years was 15,000 during 1995.

What was the standardized mortality ratio (SMR) for lung diseases in cigarette smokers?

Questions 9 and 10 are based on the information given below:

Numbers of People and Deaths from Automobile Accidents in Communities X and Y
	Community X		Community Y
Age group	No. of people	No. of deaths from automobile accidents	No. of people	No. of deaths from automobile accidents
Young	10,000	69	7,000	48
Old	13,000	115	5,000	60

Calculate the age-adjusted death rate for automobile accidents in communities X and Y by the direct method, using the total of both communities as the standard population.

What is the age-adjusted death rate from automobile accidents for community X?

What is the proportionate mortality from automobile accidents for community Y?

In your own words, explain the relationship between validity and reliability.

What is the relationship between positive predictive value and disease prevalence?

A physical examination was used to screen for prostate cancer in 5,000 men with biopsy-proven cancer of the prostate and in 10,000 age- and race- matched control men. The results of the physical examination were positive (i.e. a mass in the prostate was palpated) in 3,600 cases and in 1,600 control men, all of whom showed no evidence of cancer at biopsy.

The sensitivity of the physical examination was ____________.

The specificity of the physical examination was ____________.

The positive predictive value of the physical examination was __________.

Answer 1

The population of the city of Toronto on June 30, 2015 = 248,000

Number of new active cases of measles in Toronto occurring in 2015 = 16

Number of active measles cases according to the city register on December 31, 2015 = 355

1.Incidence rate is the number of new cases per population in the given time period. Hence, 16 is the incidence rate.

2.Prevalence rate is the total number of cases affected by the disease in that particular time. Hence, 355+16=371 is the prevalence rate.

3.Cause-Specific Mortality Rate- Mortality caused by a specific cause in a population. It is calculated by:

Number of deaths by a specific cause in a specific time / size of the population at the midpoint of the time interval.

i.e.20,000/100,000=0.2

4.Case fatality rate is by dividing the number of deaths from a specified disease over a defined period of time by the number of individuals diagnosed with the disease during that time; the resulting ratio is then multiplied by 100 to get a percentage.

hence,20,000/disease diagnosed numbersX100