Measures of Disease Frequency

Question 1

How to calculate proportion?

Answer 1

Part over whole, division of two related numbers, numerator is subset of denominatior

Question 2

How to calculate a ratio?

Answer 2

Division of two unrelated numbers, numerator not part of denominator

Question 3

How to calculate a rate?

Answer 3

Proportion with time incorporated into denominator

Question 4

What is incidence?

Answer 4

INcoming cases of disease/health event, a proportion that has the at risk pop in the denominator

Question 5

What is prevalence?

Answer 5

PREVious cases + new cases of disease/ health event, a proportion with the at risk population in the denominator

Question 6

What are other names for Incidence?

Answer 6

Risk or attack rate or cumulative incidence

Question 7

How do you calculate Risk?

Answer 7

of new cases/ # of people at risk- or in the population (minus those who already have the disease or are immune)

Question 8

75 people attended a picnic, and 46 developed gastroenteritis. What is the attack rate of gastroenteritis?

Answer 8

46/75=61.3%

Question 9

What is incidence rate?

Answer 9

number of new cases/ total PERSON-TIME at risk (or in pop)

Question 10

What is another name for incidence rate?

Answer 10

Incidence Density

Question 11

What is point prevalence?

Answer 11

prevalence at a given point in time such as a specific day

Question 12

What is period prevalence?

Answer 12

Prevelance over a given time period such as one year

Question 13

In 1989 there were 733,151 cases of gonorrhea in the US. The population mid year was 246,552,000. What was the incidence rate per 100,000 people?

Answer 13

733,151/ 246,552,000=2.97x10^-3 x 100,000 =297.36 cases per 100,000 people

Question 14

Come up with questions

Answer 14

come up with answers

Question 15

What is NNT?

Answer 15

of patients needed to be treated to receive the benefit

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