1 Lecture 10 Introduction to Surveillance • Definitions of surveillance • Objectives of surveillance • Public health vs health care surveillance • Elements of a surveillance system • Surveillance methods • Cross-sectional and longitudinal approaches • Sources of bias
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1 Lecture 10 Introduction to Surveillance Definitions of surveillance Objectives of surveillance Public health vs health care surveillance Elements of.
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Lecture 10Introduction to Surveillance
• Definitions of surveillance
• Objectives of surveillance
• Public health vs health care surveillance
• Elements of a surveillance system
• Surveillance methods
• Cross-sectional and longitudinal approaches
• Sources of bias
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Definition of surveillance(Last, Dictionary of Epidemiology. 2001)
• Systematic ongoing collection, collation, and analysis of data and the timely dissemination of information to those who need to know so that action can be taken.
• (Source: WHO)
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Definition of surveillance(Last, Dictionary of Epidemiology. 2001)
• Ongoing systematic collection, analysis, and interpretation of health data, essential to the planning, implementation, and evaluation of public health practice, closely integrated with the timely dissemination of these data to those who need to know.
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Definition of surveillance(Last, Dictionary of Epidemiology. 2001)
• Continuous analysis, interpretation, and feedback of systematically collected health data, generally using methods distinguished by their practicality, uniformity, and rapidity rather than by accuracy or completeness.
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Objectives of surveillance• Related to particular population
• Links to services– disease control– results lead to action (e.g., case or outbreak
investigation, contact tracing, interventions)
• Data for planning of services– identification of high-risk groups– projection of future service needs
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Objectives of surveillance (cont’d)
• Data for evaluation of services
• Links to research (research is not primary objective)– development of hypotheses
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Types/Sources of data
• Morbidity and mortality reports• Laboratory diagnoses• Outbreak reports• Vaccine utilization• Sickness absence• Disease determinants (e.g., reservoirs of disease)• Susceptibility measures (e.g., serological surveillance)• And many others!
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Examples of surveillance
• Communicable diseases
• Health behaviors:– Drug use, risky sexual behavior– Risk factors for chronic diseases (e.g. smoking)
• Environmental risks and diseases
• Health care
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Public health vs health care surveillance
• Public health– protection, promotion, and restoration of health
of population – includes health care services, especially if
publicly-funded
• Health care– services provided to individuals or communities
by agents of health services or professionals, to promote, maintain, monitor, or restore health. Not limited to medical care (therapy by MD)
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Public health vs health care surveillance (cont’d)
• Health care surveillance – may be part of public health surveillance (e.g.,
Montreal DSP)– also conducted by other agencies and/or health
care organizations (e.g., hospitals)
• Population may differ– public health: usually defined geographically
(district, region, country)– health care: recipients of services or catchment
population
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Objectives of surveillance of health care
• Related to particular population – e.g., catchment population, patients, clients
• Monitoring of various aspects of health care– Safety (e.g., medical errors)– Efficiency (e.g., length of stay)– Professional practices (e.g., adherence to guidelines)– Acceptability (e.g., satisfaction with services)– Equity (e.g. access)
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Health care surveillance and quality improvement
• Quality management/assurance programs– system for maintaining/improving service
– under WHO surveillance: e.g., influenza, malaria
• Regularly required:
– e.g., typhoid, diphtheria
• Others (vary by country, location):
– Selectively required
– Outbreaks of public health importance
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Surveillance methods:sentinel events
• Sentinel health event:– condition that can be used to assess the stability
or change in health levels of a population – e.g.,
• death from acute head injury a sentinel event for severe traffic injury
• death or severe health effect resulting from wrong medication, route or dose is a sentinel event for medication errors
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Surveillance methods:Sentinel surveillance
• Surveillance based on sub-populations (sentinel populations) selected to represent the relevant experience of entire population, e.g.,– networks of family physicians– schools– worksites– volunteer sites
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Surveillance methods:longitudinal vs cross-sectional