Importance of Data Management for Surveillance

1. Importance of Data Management for Surveillance Meg McCarron Epidemiologist Influenza Division, CDC

2. What is surveillance? • Main Entry: sur·veil·lance • Etymology: French, from surveillerto watch over, from sur- + veiller to watch, from Old French veillier, from Latin vigilare, from vigil watchful • Date: 1802 : close watch kept over someone or something (as by a detective) • Although the word surveillance in French literally means "watching over”, the term is often used for all forms of observation or monitoring and not just visual observation.

3. Purpose of Public Health Surveillance • Assesspublic health status • Define public health priorities • Evaluate programs • Trigger public health action

4. Rationale for surveillance The disease Society Public and mass media interest Will to prevent Availability of data Surveillance systems evolve in response to ever-changing needs of society in general and of the public health community in particular. • Severity • Frequency • Communicability • International obligations • Costs • Preventability

5. Surveillance ”Surveillance is the ongoing process of systematic collection, collation, analysis and interpretation of data; AND the dissemination of information (to those who need to know) in order that action may be taken” Information for action!

6. What Does Strategic Information Mean? • Generating information and knowledge to influence policy making, programmatic action and research • Which viruses are circulating, where, when, who is affected? • Contribute to vaccine selection • Determine intensity and impact of activity • Detect unusual events • Unusual viruses • Unusual syndromes • Unusually large/severe outbreaks • Understand the impact of influenza to guide policy and resource decisions nationally, regionally, globally

7. What do we mean by strategic information? Increasing emphasis on data use and utility ACTION! KNOWLEDGE Application Assessment INFORMATION Data demand generation Understanding DATA Analysis

8. Goals & Uses of Surveillance • Detect outbreaks or epidemics • Detect changes in trends (in time, person and place) and health practices , portray natural history of diseases • Evaluate control measures, programs or investigations • Estimate magnitude of morbidity and mortality • Ensure equity in health care (mortality and morbidity) • Facilitate planning • Making projections, understanding burden of disease and justifying allocation and or redirection of resourcese • evaluate public policy • Stimulate epidemiologic research • Generate/ Test hypotheses (e.g. changes in health practice) • Identify risk factors (in-depth studies)

9. Uses of Public Health Surveillance • serves as an early warning system for impending public health emergencies; • documents the impact of an intervention, or track progress towards specified goals; and • monitors and clarifies the epidemiology of health problems, to allow priorities to be set and to inform public health policy and strategies.

10. What do we mean by strategic information? Increasing emphasis on data use and utility ACTION! KNOWLEDGE Application Assessment INFORMATION Data demand generation Understanding DATA Analysis

11. How Do We Accomplish Step One? Data Collection! Is this Surveillance?

12. Quality Data = Quality Surveillance • Completeness • Timeliness of reporting • Usefulness of the surveillance data and the surveillance system • Simplicity of the system • Acceptability of the system • Flexibility of the surveillance system • Sensitivity in surveillance • Specificity in surveillance • Positive predictive value • Representativeness of the surveillance system

13. Elements of a Surveillance System • N° of cases (Morbidity)⇒ List of diseases, case definitions • N° of deaths (Mortality)⇒ Cause, reporting issues • Context-specific • Limited number of diseases • Criteria • High morbidity (frequency) • High mortality (severity) • Epidemic potential (communicability, international obligations, preventability …) • Standardised case definition Numerator • Prospective surveillance • Health structures • Cemeteries, burial sites • Home visitors • Death registries • Retrospective mortality survey Caution ! underreporting – double counting *k/time Population under surveillance Denominator • Possible sources • Census, registration • During emergencies : mapping, extrapolation from vaccination survey, oral accounts • Population movements / changes • Particular groups at risk (ex. orphans, single women) Total population of country/town/… Age and sex distribution New arrivals/departures, births /deaths (population movement) Census?  feasibility No need to be perfect

14. Strategy: Active - Passive • Active • (Active search for cases in the community : active case finding) • Surveillance staff contact health facilities to obtain data • Passive • Health facilities send the information • Stimulated passive surveillance • Routine reporting through the normal channel following a special request / stimulus • Depending on the situation • Emergency • Epidemic or not • Available communication means • Available human resources

15. Strategy: Data flow Periphery Intermediate level Central level Compilingweekly (Sat – Fri) Compiling weekly Compiling weekly reports reports Send on following Monday Send on Tuesday Event Action Data Data Event Action Weekly report Monthly report Event Feedback Feedback Action Policy decisions

16. Types of data collection Data sources: Notifiable diseases list Laboratory specimens Vital records Sentinel surveillance Registries Surveys Administrative data systems Other data sources Tools: Forms Data transfer Collection Collation Analysis Interpretation Communication Action

17. Summary • Data drives surveillance • Drives public health decisions • Drives public health actions • Drives vaccine strain selection, vaccine policy • Fundamental to a well functioning system is well planned & managed data