Public Health & Preventive Health_ Disease and Exposure

Question 1

What is relative risk?

Answer 1

The incidence of disease in those exposed to a particular factor compared to the incidence of disease in the unexposed

Question 2

How do you calculate relative risk?

Answer 2

Relative risk = (a/[a + b])/(c/[c + d])

Question 3

when is relative risk used?

Answer 3

In cohort studies and RCTs

Question 4

How do you calculate absolute risk?

Answer 4

Absolute risk = (a/[a + b]) − (c/[c + d])

Question 5

How do you calculate number needed to treat (in cases where the exposure is a treatment or intervention)?

Answer 5

Number needed to treat = 1/absolute risk

Where absoulte risk :

Absolute risk = (a/[a + b]) − (c/[c + d])

Question 6

How do you calculate an odds ratio?

Answer 6

Odds ratio = (a × d)/(b × c)

Question 7

When is an odds ratio used?

Answer 7

In case-control studies

Question 8

Why are oddes ratios used in case-control studies?

Answer 8

• In case-control studies you cannot calculate disease development, you cannot calculate relative risk.
• Odds ratios approximate the relative risk.

Question 9

What is a false negative result mean?

Answer 9

• A person with a disease who test negative for the disease.

Question 10

What does a false positive result mean?

Answer 10

• A person without a disease test positive for the disease.

Question 11

How do you calculate sensitivity?

Answer 11

TP/(TP + FN) = TP/(everyone with the disease)

Question 12

Define specificity,

Answer 12

Percent of those without the disease that tests negative.

Question 13

How do you calculate specificity?

Answer 13

Question 14

What is more desirable in a screening test, high sensitivity or high specificity?

Answer 14

High sensitivity

Question 15

What is more desirable in a confirmatory test, high sensitivity or high specificity?

Answer 15

high specificity.

Question 16

What is positive predictive value(PPV)?

Answer 16

• percent of those with positive tests that actually have the disease.

Question 17

How do you calculate PPV?

Answer 17

PPV = TP/(TP + FP) = TP/(all those with positive tests)

Question 18

What is negative predictive value NPV?

Answer 18

• percent of those who had negative tests that actually do not have the disease.

Question 19

How do you calculate NPV?

Answer 19

NPV = TN/(TN + FN) = TN/(all those with negative tests)

Question 20

How do you calculate PPV?

Answer 20

PPV = TP/(TP + FP) = TP/(all those with positive tests)

Question 21

What is negative predictive value(NPV)?

Answer 21

Percent of those with negative tests that actually do not have disease

Question 22

How do you calculate NPV?

Answer 22

NPV = TN/(TN + FN) = TN/(all those with negative tests)

Question 23

How does disease prevalence affect PPV and NPV?

Answer 23

Increasing the prevalence leads to increasing PPV, decreasing prevalence leads to increasing NPV

Question 24

What are POEMs?

Answer 24

• Patient Oriented Evidence that Matters.
• This is a method for identifying articles that are particularly high-yield for primary care physicians

Question 25

How are POEMs identified?

Answer 25

A POEM will meet the following criteria and warrants a closer look: 1. Would your patient care about the study’s outcome (ie, death rather than plaque thickness)? 2. Is it something you see in your practice at least once every 6 months? 3. If true, would the study’s findings change what you do (or are you already doing what the study is telling you to do)?