Surveillance-public Health Flashcards
What comes to mind when you hear surveillance?
Define surveillance
What does it include?
What is surveillance?
What comes to mind when you hear ‘surveillance’?
•Law enforcement agencies
•CIA
•Routine data collection
•Statistics
•Trends
Definition of Surveillance
•The ongoing systematic collection, analysis, and interpretation of outcome-specific data for use in the planning, implementation, and evaluation of public health practice.
•Includes data collection, analysis, and dissemination to those responsible for prevention and control.
Surveillance is:
Systematic, ongoing…
–Collection
–Analysis
–Interpretation
–Dissemination
•…of health outcome data
Health action
•investigation
•control
•prevention
What is the purpose of surveillance
Purpose of Surveillance
•To assess public health status, to define public health priorities, to evaluate programs, and to stimulate research.
–Tells us where the problems are, who is affected, and where the programmatic and prevention activities should be directed.
State six ways surveillance data can be used
How can surveillance data be used?
•Estimates of a health problem
•Natural history of disease
•Detection of epidemics
•Distribution and spread of a health event
.Hypothesis testing
•Evaluating control and prevention measures
•Monitoring change
•Detecting changes in health practice
•Facilitate planning
Explain how surveillance data can be used to facilitate planning
Explain how surveillance is outcome oriented
Uses of Surveillance Data:
Facilitate Planning
•Identify target populations in need of health services
–Refugee populations
–Morbidity surveillance in emergency shelters
•Identify health topics to be addressed by educational programs and media
Outcomes
•Surveillance is outcome oriented.
•Can measure frequency of an illness or injury (e.g., number of cases, incidence, prevalence)
•Can measure severity of the condition (e.g., hospitalization rate, disability, case fatality)
•Can measure impact of the condition (e.g., cost)
•Orient data by person, place, and time
State the steps in planning a surveillance system
Planning a Surveillance System
•Establish objectives
•Develop case definitions
•Determine data source or data collection mechanism
•Field test methods
•Develop and test analytic approach
•Develop dissemination mechanism
•Assure use of analysis and interpretation
What things should be under surveillance
What Should be Under Surveillance?
•Establish priorities based on:
–Frequency (incidence, prevalence, mortality)
–Severity (case-fatality, hospitalization rate, disability rate, years of potential life lost)
–Cost (direct and indirect)
–Preventability
–Communicability
–Public interest
–Will the data be useful for public health action?
Explain case definition under surveillance methods (what is included)
Surveillance Methods:
Case Definition
•Important to clearly define condition
•Ensures same criteria are used by all
•Makes the data more comparable
•Include person, place, time
•May define suspected and confirmed cases
•May include symptoms, lab values, time period, population as appropriate
Give some examples of case definition
Case Definition Examples
•Weak Definition - Measles
–Any person with a rash and fever, runny nose, or conjunctivitis
•Better Definition - Measles
–Any person with a fever >101 F, runny nose, conjunctivitis, red blotchy rash for at least 3 days, and laboratory confirmation of IgM antibodies
•Clinical, Probable, Confirmed Case Definitions
•Outbreak Case Definition
–Differs from routine surveillance
–Epidemiologically linked cases often included
Give a case definition of giardiasis
Case Definition Example: Giardiasis
Clinical description
•An illness caused by the protozoan Giardia lamblia (aka G. intestinalis or G. duodenalis) and characterized by gastrointestinal symptoms such as diarrhea, abdominal cramps, bloating, weight loss, or malabsorption.
Laboratory criteria for diagnosis
Laboratory-confirmed giardiasis shall be defined as the detection of Giardia organisms, antigen, or DNA in stool, intestinal fluid, tissue samples, biopsy specimens or other biological sample.
Case classification
•Confirmed: a case that meets the clinical description and the criteria for laboratory confirmation as described above. When available, molecular characterization (e.g., assemblage designation) should be reported.
•Probable: a case that meets the clinical description and that is epidemiologically linked to a confirmed case.
Explain data collection as a surveillance method (active and passive surveillance)
Surveillance Methods:
Data Collection
•Data collection
–Standardized instruments, field tested
•Passive surveillance*
–Providers are responsible for reporting
–Health dept. waits to receive reports
–Problem with underreporting
•Active surveillance*
–Providers contacted on regular basis to collect information
–More resource intensive
–Used for outbreaks or pilot studies
- These are very key concepts
Explain data analysis and interpretation and dissemination of data under surveillance methods
Surveillance Methods:
Data Analysis
•Ongoing review
•Descriptive statistics, multivariate analyses
•Automated analyses
Surveillance Methods:
Interpretation and Dissemination
•Presentation of data in the form of tables, graphs, maps, etc.
•Disseminate data via reports, presentations, internet, etc.
Explain evaluation as a surveillance method
Surveillance Methods: Evaluation
•Did the system generate needed answers to problems?
•Was the information timely?
•Was it useful for planners, researchers, etc?
•How was the information used?
•Was it worth the effort?
•What can be done to make it better?
•(More on evaluation later).
Explain the cycle of surveillance
State six data sources
Cycle of Surveillance
•Data Collection
–Pertinent, regular, frequent, timely
•Consolidation and Interpretation
–Orderly, descriptive, evaluative, timely
•Dissemination
–Prompt, to all who need to know (data providers and action takers)
•Action to Control and Prevent
•Evaluation
Data Sources:
•Vital Statistics
•Notifiable Diseases
•Registries
•Sentinel Surveillance
•Syndromic Surveillance
•Surveys
•Administrative Data
State five examples of vital statistics
State five uses of vital statistics data
Data Sources:
Vital Statistics
•Live Births
•Deaths
•Fetal Deaths
•Marriages
•Divorces
•Induced Terminations of Pregnancy
•Infant Mortality (link birth and death data)
Uses of Vital Statistics Data
•Monitoring long-term trends
•Identifying differences in health status within racial or other population subgroups
•Assessing differences by geographic area
•Monitoring deaths that are preventable
•Generating hypotheses about causation
•Monitoring progress toward improved health of the population; health-planning
How are vital records coded and calculated
State five things the quality of vital stats depends on
Vital Records:
Coding and Calculating
•ICD-9 historically, now ICD-10.
•Infant mortality - need number of live births for denominator in calculating rates.
•Other death rates - use total population in rate calculations.
•Crude and adjusted (standardized) rates used.
Quality of Vital Stats Depends on
•Care taken by health care providers in ascertaining cause of death and other factors
•Accuracy of coding (difficult for injuries)
•Relevance of existing codes for the condition being recorded
•Accuracy of population estimates
•Problems - don’t know onset, can’t see effect of diseases that don’t lead to death
Explain notifiable diseases as a data source
State six diseases that can be notifiable
Data Sources:
Notifiable Diseases
•States decide what is notifiable/reportable
–Based on disease occurrence, potential for outbreaks, public perception of risk, etc.
–WHO/NHS/MOH recommendations
–Different processes for generating N.D. list
•Weekly (or sometimes rapid) reporting to health departments by physicians, medical care facilities, laboratories.
–States report to CDC
Diseases:
Anthrax
Cholera
Diphtheria
Measles
Haemophilus influenzae infection
Tuberculosis
Rabies
Rubella
Monkey pox
Mumps
Poliovirus
What is the chain of communication in notifiable diseases
Physicians,labs,hospitals,care facilities report to the local H.D.(health district)
Local HD reports to regional and regional reports to central office
Central reports to other states or CDC
Explain The national electronic disease surveillance system
State three limitations of disease reporting
In Spite of Limitations…
•The best system we have for tracking communicable disease morbidity
•Information available quickly and from all jurisdictions
•Can detect outbreaks / changes in incidence
•Allows disease control measures to be implemented
True or false
Electronic Surveillance
•National Electronic Disease Surveillance System (NEDSS)
–A set of criteria developed by CDC that all public health surveillance systems must meet.
–Used to manage statewide reportable disease surveillance data
–Supported by CDC funds
Limitations of Disease Reporting
•Underreporting
–Reporting better for more serious diseases and those for which there is laboratory confirmation
–Need to seek medical consultation to be diagnosed and then reported
•Lack of representativeness of reported cases
•Inconsistent case definitions
Explain registries as a data source
State the populations covered registries
Data Source: Registries
•Information from multiple sources is linked for each individual over time.
–Diverse sources of information. E.g., hospitals (sometimes >1), pathology, death certificates.
•Used for cancer, congenital anomalies, trauma, etc.
•Most are passive but resource intensive.
•More lag in data availability due to complexity of data collection process.
Populations Covered by Registries
•Hospital-based
•Population-based
•Exposure registries
–World Trade Center Health Registry
–COVID 19 Cases
What are sentinel systems?
What are sentinel health events
What are sentinel sites or providers
Data Source: Sentinel Systems
•To gather timely public health information in a relatively inexpensive manner.
•Cannot derive precise estimates of prevalence or incidence in the population.
•Sentinel health events
•Sentinel sites
•Sentinel providers
Sentinel Health Events
•A condition whose occurrence serves as a warning signal.
•Particularly useful for occupational exposures.
•Silicosis, occupational asthma, pesticide poisoning, lead poisoning, carpal tunnel syndrome.
•Cases trigger intervention activities.
Sentinel Sites or Providers
•Surveillance at certain hospitals, clinics, or physician practices.
•Sentinel sites - monitor conditions in subgroups that may be more vulnerable
–E.g., drug clinic, STD clinic, MCH clinic
•Sentinel providers - monitor activity in ambulatory care settings.
–For diseases that are not reportable
–For influenza…
Explain how the sentinel system will be done for flu surveillance
Flu Surveillance
•Visits for influenza-like illness (ILI)
•Sentinel Providers / Lab Surveillance
•Outbreak Surveillance (and control)
•Pediatric Deaths – report to health dept if flu-associated death and age < 18
•Weekly Activity Level
•Influenza Incidence Surveillance Project
What is syndromic surveillance
State some complaints tallied jnto syndrome categories
State four uses of syndromic data
Syndromic Surveillance
•Uses pre-diagnostic indicators to identify emerging health problems
Onset of symptoms
Self medication
Medical consultation
Medical care
Laboratory testing
Diagnosis
Prescription
filled
Insurance billed
Syndromes
•Complaints tallied into syndrome categories
–Death
–Sepsis (serious infection)
–Rash
–Respiratory (e.g., cough)
–Gastrointestinal (e.g., diarrhea)
–Unspecified Infection (fever)
–Neurological (e.g., dizziness)
–Other
Uses of Syndromic Data
•Monitor trends in influenza, gastrointestinal illness
•Detect outbreaks or individual cases of disease, especially illnesses with unique symptoms or names (e.g., scombroid poisoning)
•Special event surveillance (e.g., Olympic Games, Presidential Inauguration, etc.)
•Disaster surveillance (e.g., hurricanes, ice storms, etc.)
Explain surveys under data sources
What is it’s use?
How are national surveys done?
State three other examples of surveys
Data Source: Surveys
•If done continually or periodically, can monitor risk factors and changes in prevalence over time
•Can also assess knowledge, attitudes
•People usually queried only once and not monitored on an individual basis after that
•From questionnaires, interviews (in person or telephone), or record review
National Surveys – www.cdc.gov/nchs
•National Health Interview Survey
–Random selection of households
–In-home interview gathering information on all in the household
–Self-reported illnesses, chronic conditions, injuries, impairments, use of health services
–Civilian, non-institutionalized population
Other Survey Examples
•Exit interviews at health facilities
•Special studies
–Risk-behavior
•Cluster surveys
–Rapid surveillance after emergencies
Explain administrative data as a data source ?
Usefulness of Administrative Data depends on what things?
•Routinely collected for other reasons.
•E.g., hospital discharge data collected for billing purposes, Medicaid and Medicare data, emergency department data, data collected by managed care organizations.
Usefulness of Administrative Data
•Depends on:
–What information is computerized
–Standardization of codes for diagnoses, symptoms, procedures, reasons for the visit
–Time between occurrence of health event and availability of data
–Ability to link with other data systems
–Whether supplementary information can be obtained
State five other important surveillance systems
Other Important
Surveillance Systems
•Injury
•Diabetes
•Child/Adolescent Hospitalizations
•Special temporary systems
•Drug safety
•Food safety
•Etc. – Public health collects a lot of information on the health of our communities!
How can surveillance data be analyzed?
Analysis of Surveillance Data
•Line list of cases – include demographic and clinical info, risk factors, lab results, etc
•Descriptive epidemiology
–Person: age, race/ethnicity, sex
–Place: county, district, state
–Time: day, month, year – onset vs. reported
•Incidence and prevalence
–Rates – crude, specific, standardized
•Trends and seasonality
•Geographic clustering (maps)
What are the limitations of interpreting surveillance data?
What things should you consider?
State four interpretive uses of surveillance data
Interpretation of Surveillance Data
•Limitations
–Under-reporting
–Biased reporting
–Inconsistent case definitions
•Consider context
–Seasonality
–Recent policy changes or interventions
Interpretative Uses of
Surveillance Data
•Identifying epidemics
•Identifying new syndromes or risk groups
•Monitoring trends
•Evaluating public policy
•Projecting future needs
How is data disseminated ?
Data Dissemination
•What should be said? To whom? Through what communication medium? How should the message be stated? What effect did the message create?
•Determine answers based on the purpose of the system.
•SOCO - single overriding communication objective. [What is new? Who is affected? What works best?]
The message is given to the audience through channels
How can you evaluate surveillance systems
Evaluating Surveillance Systems
•System objectives and usefulness
–Actions taken as a result of the data.
–Does the system do what it’s supposed to do?
•Operation of the system
–Who is reporting? To whom? What information is collected? How is information stored? Who analyzes the data? What are the findings? How often are reports disseminated? to whom?
•Cost
State and explain the system attributes of evaluating surveillance systems (six attributes)
Evaluation - System Attributes
•Simplicity
–Should be as simple as possible and as easy to operate as possible.
•Flexibility
–Should be able to adapt to changing needs.
•Acceptability
–Willingness of individuals or organizations to participate in the surveillance system. (Judge based on completeness, timeliness, reporting)
Evaluation - System Attributes
•Sensitivity
–Proportion of cases detected by the system. Completeness of reporting. Detect epidemics?
–Increased awareness, new diagnostic test, change in surveillance method may impact.
•Predictive Value Positive
–Proportion of persons identified as having the disease who actually have it.
Evaluation - System Attributes
•Representativeness
–Do the characteristics of reported events compare favorably with those in the population.
–Is there case ascertainment bias?
–Bias in descriptive information about a reported case?
•Timeliness
–Any delay between the steps? (onset, diagnosis, report to public health, disease control actions)
CDC Guidelines for Evaluating Public Health Surveillance Systems: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5013a1.htm
State five ethical and legal issues relating to surveillance
Conclusion
•Surveillance provides information on the health of the community
•Public health relies on information from medical care providers and takes prevention-oriented actions based on information received
•Surveillance involves taking information in, analyzing & interpreting it, and disseminating it to those who need it
True or false
Ethical and Legal Issues Relating to Surveillance
•Professional obligations
•Protecting confidentiality and privacy
•Informed consent
–Mandated activity vs. research
•Maintaining public trust
•Right of Access
Look at the slide on sensitivity/specificity and predictive value
