How do you calculate the disease frequency rate in these problems

1. The cumulative incidence rate in a population of 100,000 people where 9 new cases of disease were reported within 1 year
2. The prevalence of a chronic disease on November 1st where 9 initial cases were found in September with an additional 45 cases reported in October of a small city with a population of 75,000 people.
3. The relative risk of death from exposure A if the mortality rate in the exposed group is 60 deaths per 1000 person-years and the mortality rate in the unexposed group is 20 per 1000 person-year

1. nine cases per year: 9/100,000 per year

2. Really, not enough information, but since it is a chronic disease, so there is no information to believe it is changing: 27 cases/75000 per month

3. risk of death= 40 per/1000person-year

To calculate the disease frequency rate in these problems, you need to determine the appropriate measure based on the information given. Here's how you can calculate the rates for each problem:

1. Cumulative Incidence Rate:
The cumulative incidence rate measures the number of new cases of a disease within a specific time period in relation to the population at risk. To calculate it, you need to divide the number of new cases by the population size and multiply by a constant (usually 100 or 1,000) to express it as a rate per unit of population.

For the given problem:
Number of new cases = 9
Population size = 100,000

Cumulative Incidence Rate = (Number of new cases / Population size) x 1000
= (9 / 100,000) x 1000
= 0.09 per 1,000 population

Therefore, the cumulative incidence rate is 0.09 per 1,000 population.

2. Prevalence:
Prevalence represents the total number of cases of a disease (both old and new) at a specific point in time in relation to the population at risk. To calculate it, you need to add the number of existing cases to the number of new cases and divide by the population size.

For the given problem:
Number of existing cases = 9
Number of new cases = 45
Population size = 75,000

Prevalence = (Number of existing cases + Number of new cases) / Population size
= (9 + 45) / 75,000
= 0.72 per 100 population

Therefore, the prevalence is 0.72 per 100 population.

3. Relative Risk:
Relative Risk is a measure of the strength of association between a risk factor and an outcome. It compares the risk of developing the outcome in the exposed group to the risk in the unexposed group. To calculate it, you need to compare the two mortality rates.

For the given problem:
Mortality rate in exposed group = 60 deaths per 1,000 person-years
Mortality rate in unexposed group = 20 deaths per 1,000 person-years

Relative Risk = (Mortality rate in exposed group) / (Mortality rate in unexposed group)
= (60 / 1,000) / (20 / 1,000)
= 3

Therefore, the relative risk is 3.

By following these explanations, you can calculate the disease frequency rates for the given scenarios.