Surveillance

Question 1

What are the objectives of surveillance? (8)

Answer 1

1. To estimate the magnitude (burden) of a health problem in the population at risk (e.g. influenza)
2. To understand the natural history of a disease/injury (e.g. HIV)
3. To determine the distribution and spread of a disease or health event
4. To detect outbreaks or epidemics
5. To generate hypotheses about aetiology
6. To monitor changes in infectious agents, disease incidence and health practice (e.g. antimicrobial resistance, caesarian section)
7. To evaluate the effectiveness of control strategies e.g. vaccine programs
8. To monitor isolation activities

Question 2

What are some quantitative methods to decide if a condition should be under surveillance? (6) e.g. if comparing 2 conditions

Answer 2

Frequency (incidence, prevalence, mortality)
Severity (case-fatality, hospitalisation rate, disability rate, YLL, QALY)
Cost (direct and indirect)
Preventability
Communicability
Public interest

Question 3

What are the CDNA criteria (qualitative) for deciding whether a disease should be under surveillance? (10)
(6 re. disease, 2 general, 2 logistical)

Answer 3

1. Public health importance
2. Is available data insufficient?
3. Is surveillance needed to guide prevention and control?
4. Is baseline information needed? e.g. pre-intervention
5. Is the disease new or re-emerging? e.g. SARS
6. Is there potential for outbreaks?
7. Are there inequities e.g. Indigenous health?
8. Is there public concern or political interest?
9. Is surveillance feasible?
10. Is the condition definable?

Question 4

What are the different types of surveillance?

Answer 4

Passive 
Active
Enhanced passive
Syndromic
Sentinel
Risk factor (e.g. drug use, sex)
Hazard e.g environmental hazards
Rumour
Event-based

Question 5

What are the steps in setting up a surveillance system?

Answer 5

What is the purpose/goal of surveillance?

1. Stakeholder engagement (ensure ‘buy in’ from everyone involved including those collecting, reporting and using the data)
2. Establish purpose (e.g. outbreak detection) and objectives (well-defined, clearly describe what is needed e.g. passive v’s active)
3. Develop case definitions (simple, understandable, acceptable, practical, sensitive, specific. May include confirmed, probable, suspected)
4. Determine data sources, collection mechanisms and instruments (consider flexibility, representativeness, sensitivity, specificity, timeliness)
5. Field test (pilot) methods
6. Develop and test analytic methods (consider who will do analysis and how? what will be analysed, specify types of graphs/tables etc.)
7. Develop dissemination mechanism
8. Plan use and interpretation of analyses (for public health action)
9. Monitor and evaluate

Question 6

What are the steps in evaluating a surveillance system?

Answer 6

1. Engage the stakeholders
2. Describe the surveillance system to be evaluated (public health importance, purpose and operation, resources)
3. Focus the evaluation design (determine specific purpose, plan what will be done with the information generated, specify questions/information to be collected, determine standards for assessing the system performance)
4. Gather credible evidence (usefulness, attributes: simplicity, flexibility, data quality, acceptability, sensitivity, PPV, representativeness, timeliness, stability)
5. Justify and state conclusions and make recommendations
6. Ensure use of evaluation findings and share lessons learned

Question 7

What attributes should be considered in evaluating a surveillance system?

Answer 7

CART SPUDF
Completeness
Acceptability
Representativeness and Reliability
Timeliness
Sensitivity (does it detect all events?)
PPV
Usefulness (is the system meeting its objectives?)
Data quality
Flexibility (can it be modified if necessary?)