Disease Frequency Level 1

Question 1

What is a case

Answer 1

Someone with an outcome of interest

Question 2

How can we tell how common a health state is in a population? Define+pros/cons

Answer 2

1. Count-don’t know how many out of
2. Prevalence: Number of existing cases+new cases of disease in a population at or during some designated time /average population/midpoint population (*100)
   -Expressed as % or number of cases per unit size of population
   -Indication of extent of health problem (burden)
   Pro: Helps us determine allocation of health resources such as facilities and personnel

Question 3

What is point prevalence?

Answer 3

point prevalence=number of cases (BOTH NEW AND EXISTING CASES) total number in this group at point in time (Point of time=a specific day, today on February 6 that is the point)

Question 4

What is period prevalence formula?

Answer 4

new+existing cases/average population during a time period, or can use midpoint population

Question 5

What is (cumulative) incidence, or risk

Answer 5

• Estimates the risk of the health-related event

- Number of new cases during a specified time interval/pop at risk

Question 6

How do you calculate incidence?

Answer 6

Incidence: Number of new cases over a time period/ Total population at risk during the same time period *100

Question 7

What is attack rate? How do you calculate it?

Answer 7

• Similar to cumulative incidence
• Used to quantify risk for infectious diseases
• number of cases/population at risk

Question 8

What is loss to follow up?

Answer 8

When somebody drops out of your study

Question 9

Incidence density (rate)

Answer 9

• Used when measures of population are under observation for different lengths of time
• person-time of observation as denominator

Question 10

What is person-time?

Answer 10

sum of periods of time at risk for each member of population

Question 11

What is the formula for incidence density (rate)?

Answer 11

incidence density= number of new cases during the time period/total person-time of observation

Question 12

If period of observation is measured in years, formula becomes:

Answer 12

incidence density=number of new cases during the time period/total person-years of observation

• anyone with disease cannot contribute to risk
• only count the participant for the amount of time they contributed

Question 13

What is incidence?

Answer 13

Risk of getting the disease

Question 14

When calculating point prevalence, we only use average population or mid point population?

Answer 14

Average population