Surveillance and Trends

Question 1

What is the driver of public health action?

Answer 1

Surveillance.

Question 2

What is the definition of surveillance?

Answer 2

*Ongoing, *systematic collection, *analysis, *interpretation, evaluation and dissemination of population-based health-related information to monitor and improve the health of populations

Question 3

Define ongoing in the definition of surveillance.

Answer 3

Need many data points to understand what falls in the normal versus abnormal range (find baseline).

Need to collect data CONTINUOUSLY.

Data collected at ROUTINE INTERVALS.

Critical to timely response.
Collected over long time period.

Question 4

Why is data collected over a long time period for surveillance?

Answer 4

To determine trends and burden of disease.

Question 5

Define systematic in the definition of surveillance.

Answer 5

Use standard case definition for reporting disease.

Allows for comparison across populations.

Collect data in same way over time.

Question 6

What is case definition?

Answer 6

Number of criteria a disease needs to meet.

Question 7

Define analysis in definition of surveillance.

Answer 7

Analyzing and using surveillance data justifies collection by using for PH action.

Examined by time, place, person.

Compare burden of disease and how it differs over time.

Allow for identification of pattern and trends.

Question 8

Define interpretation in definition of surveillance.

Answer 8

Analyst must understand context of numbers.

Technology can change over time.

Differences in reporting mechanisms.

Question 9

Explain the extension of police authority to states to protect public health.

Answer 9

Police powers include basic communicable disease activities to protect public against natural, accidental, or intentional threats.

Question 10

Explain how some states have authority to require disease notification.

Answer 10

Conditions vary state to state.

States are primary repository of surveillance data and have authority to collect and hold data.

Council of State and Territorial Epidemiologists (CSTE) votes to approve which disease should be reported to CDC and states voluntarily and without identifying information share that.

Question 11

What is the difference between reporting and notifying a disease?

Answer 11

Reportable means to a certain state (reported to state by law).

Notifiable means disease should be reported to CDC (as decided by CSTE).

Question 12

What are the types of surveillance?

Answer 12

5 types:

Case-based
Sentinel surveillance
Population-based surveys
Lab-based
Secondary uses of data

Question 13

Explain case-based surveillance.

Answer 13

Provider or lab reported each case they diagnose to state department based on list.

Typically only positive tests reported.

Question 14

Explain sentinel surveillance.

Answer 14

Conducted in subset of population.
Pick places that reasonably represent population as a whole.
Less resource intensive by making sure underlying population represented.

Good for monitoring trends but not good at capturing rare events.

Question 15

Explain population-based surveys.

Answer 15

Happens on a regular basis and same questions every year to monitor BH and health.

Question 16

Explain lab-based surveillance.

Answer 16

Reference lab that perform special techniques. Expensive to do these test and most commercial labs not set up.

Question 17

Explain secondary uses of data.

Answer 17

Can use big data to look at diagnoses of various conditions over time.

EX:
Billing data from Medicaid and private insurance companies are data put together with intention of billing patients for services

Question 18

What is active surveillance?

Answer 18

Proactive collection of data with primary purpose of informing surveillance activities.
Whole group that collects data like this at CDC.

Resource intensive.

Allows us to create a system to collect data by person, place, and time.

Question 19

What is passive surveillance?

Answer 19

Use of data that are external surveillance system.
Relies on reporting from other:
• Health clinics of labs
• Might be duty by law to report data

Data may be collected for purposes apart from surveillance.

More feasible, fewer resources retroactive case definition

Challenges with reporting and interpreting data but less resources.

Question 20

What are some uses of surveillance data?

Answer 20

5 uses:

Detection of outbreaks or epidemic
Helps us to understand
Generation of hypothesis
Informs prevention and control strategies
Informs forecasting of future disease transmission patters

Question 21

How does surveillance data help detect outbreaks?

Answer 21

Need to know baseline level of burden of disease.

Monitor to know if levels are normal or abnormal.

Question 22

How does surveillance data help us to understand?

Answer 22

Helps us to understand various things such as:

Burden of disease in a population.
Natural history of a disease.
Infectious agents or risk factors for disease.

Can show outcomes and risk and how these are associated and if there is a true association.

Question 23

How does surveillance data help with generation of hypotheses?

Answer 23

Not confirmatory.

Question 24

How does surveillance data inform prevention and control strategies?

Answer 24

Resource allocation and planning as we know where disease is located.

Evaluates effectiveness by looking at disease before and after control strategies.

Use ongoing data to understand what is most effective.

Question 25

How does surveillance data help to inform forecasting of future disease transmission?

Answer 25

Data from previous years can be used to predict disease in future.

How to formulate vaccine, when to expect it, where, etc.

Question 26

Explain how surveillance data analyzed by time.

Answer 26

Can be days, months, years.

Question 27

How many data point are needed to assess trends?

Answer 27

At least 5.

Do not test a trend you cannot visually see.

Question 28

Detail linear regression.

Answer 28

There is a change in Y for each 1 unit change in X. Can model slope of line.

Question 29

Give examples of some causal changes.

Answer 29

People taking medications.

Diagnosed earlier.

Question 30

Give examples of non-causal changes.

Answer 30

Difference in race or ethnic makeup of population.
Difference in income.

To understand the extent to which things improve or decline, we must account for NON-CAUSAL CHANGES.

Question 31

How can we account for population changes over time?

Answer 31

Stratification.

Separately assess changes in demographic groups.

Question 32

What can cause changes in trends?

Answer 32

Four reasons:

Number of infections
Screening practices
Diagnostic practices
Reporting practices

Question 33

Give examples of number of infections.

Answer 33

Asymptomatic may never get reported.

Question 34

Give an example of screening practices.

Answer 34

The more you look, the more you find.

Screening campaigns can increase number.

Question 35

Give an example of diagnostic practices.

Answer 35

Change in tech and difference in sensitivity.

Symptomatic versus lab confirmation.

Question 36

Give an example of reporting practices.

Answer 36

Case definition may change.
Timeliness of reporting.
Case reporting based on cooperation between different levels.

Question 37

What is the relationship between case definitions and case reports?

Answer 37

Defines which cases should be counted and reported.
Ensure consistent measurement over time.
Ideally same across all geographic areas across populations.
May be different based on screening practices.

Question 38

What is case-fatality?

Answer 38

A ratio. Number of deaths to number of cases.