Surveillance

1. Surveillance Dr. Oswaldo S. Medina Gómez

2. Definition • Continuous and systematic process of collection, analysis, interpretation, and dissemination of descriptive information for monitoring and investigate health problems

3. Objectives • Descriptive epidemiology of health problems. • Links to services. • Links to research. • Evaluation of interventions. • Projections and planners. • Education and policy.

4. Surveillance system • Case definition. • Population under surveillance. • Cycle of surveillance. • Confidentiality. • Incentives to participation.

5. Approaches to surveillance • Active or passive surveillance? • Notifiable disease reporting. • Laboratory- based surveillance. • Volunteer providers.

6. Approaches to surveillance • Registries. • Surveys. • Information system • Sentinel events. • Record linkages.

7. Registries • Are listings of all occurrences of a disease, or category of disease within a defined area. • Registries collect relatively detailed information and may identify patients for long-term follow-up for specific laboratory or epidemiologic investigation.

8. Survey • Provide a method for monitoring behaviors associated with disease, personal attributes that affect disease risk, knowledge/attitudes that influence health behaviors, use of health services, and self-reported disease occurrence.

9. Information system • Are data bases collected for general, rather that disease-specific purposes, which can applied to the surveillance of specific conditions.

10. Sentinel Events • The occurrence of rare disease known to be associated with a specific exposure can alert health officials to situations where others may have been exposed to a potential hazard.

11. Sentinel Events • Surveillance for sentinel events can be used to identify situations where public health investigation or intervention is required.

12. Record linkages • Linkage of surveillance records to an independent data source can be used to identify previously undetected cases and thus measure and improve the completeness of surveillance

13. Analysis of surveillance data • The analysis of surveillance is descriptive and straightforward, using standard epidemiologic techniques. • Comparisons between groups may require steps to assess and control for confounding, and more advanced analytic techniques may be required.

14. Attributions of surveillance • Sensitivity. • Timeliness. • Representativeness. • Predictive value.

15. Attributions of surveillance • Accuracy and completeness of descriptive information. • Simplicity. • Flexibility. • Acceptability.

16. Sensitivity • Extent does the system identify all the events in the target population. • For purposes of monitoring trends, low sensitivity may be acceptable if sensitivity is consistent over time and detected events are representative.

17. Timeliness • Entire cycle of information flow, ranging from collection to dissemination.

18. Representativeness • Events detected through the surveillance system represent persons with the condition of interest in the target population

19. Accuracy and completeness of descriptive information • Forms of reporting health events often include descriptive personal information