Lecture 1: Principles of PH surveillance

Question 1

Big names in history of PH Surveillance

Answer 1

John Graunt (analyzed bills of mortality), William Farr (first medical statistician), Edwinn Chadwick (poverty and disease closely related), Johann Peter Frank, Karel Raska, Mirabeau

Question 2

1st national health survey

Answer 2

1935

Question 3

1st mmwr (morbidity and mortality weekly report)

Answer 3

1952

Question 4

Surveillance is:

Answer 4

collection, analysis and dissemination of data

Question 5

Personal Surveillance is:

Answer 5

monitoring potentially exposed people for the detection of early symptoms.

Question 6

Epi surveillance is:

Answer 6

study of disease as a dynamic process involving ecology of the infectious agent, host, reservoirs and vectors. Also concerned with spread of infection and the extent to which this spread occurs

Question 7

Components of epidemiological surveillance

Answer 7

• Systematic collection of data
• Consolidation and analysis of the collected data
• Dissemination of information by means of narrative epi reports
• Follow-up to ensure that effective action had taken place

Question 8

2001 Definition of Public Health surveillance

Answer 8

The ongoing systematic collection, analysis, interpretation and dissemination of data regarding a health-related event for use in public health action to reduce morbidity and mortality

Question 9

Purpose of Public health surveillance

Answer 9

• Assess public health status
• track important public health conditions
• define public health priorities
• evaluate programs
• develop public health research

Question 10

Uses of public health surveillance

Answer 10

• quantitate the magnitude of a health problem (ex. using charts that show increase in incidence of disease among different ages)
• portray the natural history of disease (ex. using graphs to show that a disease has decreased in prevalence over time)
• detect epidemics (ex. using graphs to monitor disease over time and then later on seeing if they rise above the normal level)
• document the distribution of a health event (ex: graph showing obesity trends around the USA, where they are most concentrated, where there is no data, etc.)

Question 11

Summary of PH Surveillance uses

Answer 11

• facilitate epidemiologic and lab research
• generate and test hypotheses
• evaluate control and prevention measures
• monitor changes in infectious agents
• monitor isolation activities
• detect changes in health practice
• plan public health actions and use of resources
• appropriate and allocate prevention and care resources

Question 12

Some factors to consider during ph surveillance system development

Answer 12

• establish objectives
• develop case definitions
• determine surveillance systems
• data security and confidentiality
• field testing
• data collection
• develop data collection instruments
• develop and test analytic approach and data interpretation
• develop a dissemination and communication method for data
• analyse and interpret
• evaluate surveillance system

Question 13

Measures to identify priority health events for surveillance

Answer 13

-Frequency (Incidence, prevalence, mortality)
-Severity (case-fatality ratio, Quality adjusted life year lost, disability and hospitalization rates)
-Cost
-preventability
communicability
-public interest

Question 14

5 examples of objectives for ph surveillance system

Answer 14

• Estimate burden of disease
• under stand natural history of disease
• detect outbreaks
• assess quality of health care
• identify research needs

Question 15

Case definition development

Answer 15

• Must be defined relative to person, place and time
• must include diagnostic criteria for confirmed vs. suspected cases
• must include clinical criteria for diagnosis and epi features
• based on the clinical criteria, one can then determine which a confirmed case is and which is suspected.

Question 16

Difference between confirmed case and a probable or suspected case

Answer 16

• The probable case will have 1 or more of the symptoms associated with the disease, however, there may be no laboratory confirmation or epidemiologic linkage to a lab confirmed case. However, in some instances, the probable case may have the symptoms as well as contact with a lab confirmed case or the probable case may have symptoms as well as a lab positive test.
• The confirmed case on the other hand will meet the clinical criteria, lab criteria as well as the epi linkage criteria (which links the person to anyone who has lab confirmation of being a case)

Question 17

Types of Surveillance systems (1)

Answer 17

• Primary/routine surveillance systems such as active and passive
• Active: involves active outreach to healthcare professionals (pro of being more complete and timely and con of being more labor intensive and lasting a short period of time)
• Passive: healthcare providers report (pro of being cheaper, but con of being late and incomplete)

Question 18

Types of Surveillance systems (2)

Answer 18

• Limited surveillance system–> frequently done for a short period of time to address specific issues sometimes in select geographic region
• It is always good to piggyback on existing systems when possible

Question 19

Data collection instruments

Answer 19

• collection tools must be standardized
• minimization of data entry errors is a must
• prior thought about how to analyze the data collected

Question 20

Field test

Answer 20

minimizes probability of the need to make changes to system once it has been implemented on a broader scale

Question 21

Develop dissemination mechanism

Answer 21

-data must be disseminated and communicated to those who are capable of using that data for public health interventions

Question 22

When is Surveillance appropriate?

Answer 22

• high priority events

- when appropriate action can be taken

Question 23

When is Surveillance not appropriate?

Answer 23

When doing it for research purposes only

Question 24

Elements (Attributes) of a surveillance system

Answer 24

• Simplicity
• Flexibility (accommodates evolving disease patterns)
• Data quality (contains complete and valid data)
• Acceptability (for those participating in the system)
• Sensitivity (be sensitive enough to detect event of interest)
• Positive predictive value (have high PPV to avoid expenses on follow up of FN’s)
• Representativeness
• Timeliness
• Stability

Question 25

Justifying the system: Uses

Answer 25

• identify newly emergent health problems and infections
• assess PH impact of problems and measuring temporal trends in disease burden
• identify correlative risk factors for disease acquisition or progression
• allocating resources to manage disease, care and control
• evaluate effectiveness
• support research inquiries and hypothesis generation

Question 26

Rival goods

Answer 26

a good that once consumed, cannot be consumed by others (ex. vaccine dose).
-a non-rival good is the opposite and example would be a radio broadcast

Question 27

Excludable goods

Answer 27

goods that seller can restrict access based on payment (ex. medical care, vaccines)
-non excludable goods are the opposite and access cannot be restricted (ex. fish caught in a lake)

Question 28

Public goods

Answer 28

non-rival, non excludable & non-rejectable

Question 29

Common goods

Answer 29

rival, non-excludable & rejectable

Question 30

Toll “club” goods

Answer 30

non-rival and excludable

Question 31

Private goods

Answer 31

rival and excludable