Measure Of Disease Occurence

Question 1

Why should you measure disease?

Answer 1

1. To identify important diseases and changing disease patterns
2. To compare disease in groups to establish what the risk factors are an there causes

Question 2

What two types of health problems is epidemiology concerned with ?

Answer 2

1. The presence of existing health problems in a population

2. The occurrence of new health events in a population (and their measurement)

Question 3

Epidemiologists measure:

Answer 3

1. The amount of disease in population at one point in time, or over a period of time
2. The change in the amount of disease in a population over a period of time

Question 4

When measuring disease occurrence it is important to define:

4 things

Answer 4

1. What is being measured
2. The persons or animals included in the measurement (study population)
3. Place or location of the study population
4. Time period of the study

Question 5

Which is NOT one of the 3 types of populations that measure disease occurrence ?

A. Source population
B. Target population
C. Spanning population
D. Study population

Answer 5

C. Spanning population

Question 6

Define study population:

Answer 6

• animals you actually measure (subjects in the study)
• usually a ‘sample’ from a source
• the number ‘n’ of subjects in the study population

Question 7

Define source population:

Answer 7

Population from which the subjects were drawn

Question 8

Define target population:

Answer 8

Population to which we may want to generalize our results

Question 9

What are the 4 most common types of measure in epidemiology?

Answer 9

Counts
Proportions
Ratios
Rates

Question 10

The number of animals that. Have the disease (or condition of interest) is what type of measure ?

Answer 10

Count

Disadvantage: doesn’t tell you how many of the total population had the disease; they convey very little information

Question 11

The count of animals w/ the disease, as a fraction of the total animals that could be disease is called what?

Answer 11

Proportion

Main measure of disease occurrence
Often expressed as fractions or percentages

Question 12

The most commonly used proportion in epidemiology is ________

Answer 12

Prevalence

Question 13

A fraction in which the numerator is not part of the denominator. (Comparing two different things) is called a _______

Answer 13

Ratio

A commonly used ratio in epidemiology is the odds

Question 14

Rates measure ________ (old/new) events (choose one)

Answer 14

New

Question 15

Define rate:

Answer 15

A measure of the frequency with which an event occur in a defined population over a specified period of time

Question 16

The most commonly used rates in epidemiology are:

Answer 16

Cumulative incidence and incidence rate

Question 17

Prevalence:

Answer 17

The proportion of the study population that is diseases at any one time (point in time or period)

Provides info about how frequently you might expect to see the condition in your practice

• the probability of an animal from the study population being diseased

Question 18

How do you calculate point prevalence ?

Answer 18

Number of cases of disease present in the population at a particular time / total population at that time

Question 19

Incidence:

Answer 19

The number of new cases of disease that occur in the study population over time

• the probability of a disease-free animal from the study population becoming diseased (risk of becoming diseased)

Question 20

Cumulative incidence:

Answer 20

The proportion of disease-free individuals in the study population who became diseased during a specified period of time

Based on assumptions
The entire population at risk must be followed Fromm the start of the study until the end

Question 21

Attack rate:

Answer 21

A cumulative incidence during an outbreak

Applied to a narrowly-defined population

Probability of becoming diseased during the course of an outbreak

Question 22

Incidence rate (2nd kind of incidence):

Answer 22

Instantaneous rate of occurrence of new cases of disease among non-diseased animals in the population

Question 23

Prevalence vs. incidence

Answer 23

Prevalence: a measure of the amount of disease in a population (includes all cases, old and new) [Used for chronic conditions]]
Incidence: a measure of the rate of disease occurrence. (Only new cases) [Used for acute cases]

Question 24

Prevalence depends on::

Answer 24

1. Incidence and,

2. Duration of disease