introduction to surveillance
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Introduction to Surveillance. Session 4, Part 1. Learning Objectives Session 4, Part 1. Explain the surveillance “feedback loop” of data and information flow through local, state, and federal channels - PowerPoint PPT PresentationTRANSCRIPT
Introduction to Surveillance
Session 4, Part 1
Learning ObjectivesSession 4, Part 1
• Explain the surveillance “feedback loop” of data and information flow through local, state, and federal channels
• Describe characteristics of three different methods of surveillance: active, passive, and syndromic
• List 5 applications of public health surveillance
OverviewSession 4, Part 1
• How surveillance works• Passive, active, and syndromic
surveillance• Applications of surveillance data• Surveillance limitations and challenges
How Surveillance Works
What is Surveillance?
The 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 to
those who need to know.
- Centers for Disease Control and Prevention (CDC)
• Physicians• Laboratories• STD clinics• Community health clinics
• Emergency departments (EDs)
County and state health departments, CDC analyze data using statistical methods
Standardized data collection
Surveillance Flow
• Physicians• Laboratories• STD clinics• Community health clinics
• EDs
County and state health departments, CDC analyze data using statistical methods
• Public health officials• Health directors• Health policy officials
Standardized data collection
Dissemination to those who need to know
Dissemination to those who need to know
Surveillance Flow
• Physicians• Laboratories• STD clinics• Community health clinics
• EDs
County and state health departments, CDC analyze data using statistical methods
• Public health officials• Health directors• Health policy officials
Standardized data collection
Dissemination to those who need to know
Dissemination to those who need to know
Change in public health practice (vaccination, reduction of risk factors, medical intervention, etc.)
Public health planning and intervention
Surveillance Flow
• Physicians• Laboratories• STD clinics• Community health clinics
• EDs
County and state health departments, CDC analyze data using statistical methods
• Public health officials• Health directors• Health policy officials
Standardized data collection
Dissemination to those who need to know
Dissemination to those who need to know
Change in public health practice (vaccination, reduction of risk factors, medical intervention, etc.)
Public health planning and intervention
Public health evaluation
Surveillance Flow
National Notifiable Diseases Surveillance System (NNDSS)
• National list– ~60 nationally infectious diseases – ~6 non-infectious diseases / conditions– Produced by CSTE each year
• State list– Each state modifies as needed– State law mandates reporting requirements
Sources of Surveillance Data
• Mortality reporting – Legally required as part of vital statistics
programs in most countries• Morbidity reporting
– Notifiable disease reporting (legally required) or specially created systems
Sources of Surveillance Data
• Surveys, e.g. BRFSS• Epidemic reporting / cluster investigation• Laboratory investigations and reporting• Individual investigations
Management of Surveillance Data
• Timeliness• Completeness• Accuracy
Analysis of Surveillance Data • Trends• Clusters• Patterns
Methods of Surveillance
PassiveActive
Syndromic
Passive Surveillance
Laboratories, physicians, or other health care providers regularly report cases of disease to the local or state health department based on a standard case definition of that particular disease.
Communicable Disease Reporting:Passive Surveillance
Hospital PhysicianLab
Local Health
DepartmentState
CDC
Public
Excerpt: 2011 Recommended Reportable Diseases
• Anthrax• Arboviral neuroinvasive
and non-neuroinvasive diseases– California serogroup virus
disease– Eastern equine encephalitis
virus disease– Powassan virus disease– St. Louis encephalitis virus
disease– West Nile virus disease– Western equine encephalitis
virus disease• Babesiosis
• Botulism– Botulism, foodborne– Botulism, infant– Botulism, other (wound &
unspecified)• Brucellosis• Chancroid• Chlamydia trachomatis
infection• Cholera
Specific reportable diseases and conditions are mandated by state law, and can differ for every state.
Active Surveillance
Local or state health departments initiate the collection of specific cases of disease from laboratories, physicians, or other health care providers.
Communicable Disease Reporting:Active Surveillance
Hospital PhysicianLab
Local Heath Department
State
CDC
• Outbreak investigations
• Other times when complete case ascertainment is desired – Research study– Incomplete information
reported
Active Surveillance Applications
Advantages and Limitations
Passive Surveillance• Advantages
– Inexpensive– Low data collection
burden for health department
• Limitations– Under-reporting– Missing information – Can be slow
Active Surveillance• Advantages
– Complete data– Flexible
• Limitations– Costly
Syndromic Surveillance
The ongoing, systematic collection, analysis, interpretation, and application of real-time indicators for disease that allow for detection before public health authorities would otherwise identify them.
What are “Indicators of Disease?”
• Clinical signs that we can categorize into syndromes
• Not a specific diagnosis
Example: Cough + Sore throat + Fatigue + Fever =
Influenza-like illness
Syndromic Surveillance Example
Source: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=18905
Daily temperatures and GP visits for heat syndrome, Bordeaux, 1 June – 31 Aug, 2006
Common SyndromesUnder Surveillance
• Gastroenteritis• Influenza-like illness (ILI)• Meningitis / Encephalitis• Rash / Fever sydromes• Botulinic syndrome• Hemorrhagic syndromes
Why Do Syndromic Surveillance?
• Early detection– Ideally automated
• Outbreak characterization– Magnitude, rate of spread,
effectiveness of control measures
• Detection of unexplained deaths
Limitations of Syndromic Surveillance (1)
• Limited by available data– False alarms– Inconsistent reporting sources– IT failure
Limitations of Syndromic Surveillance (2)
• Inadequate sensitivity: failure to detect outbreaks or emergencies– Outbreak is too small– Population disperses after exposure, cluster
not evident
Limitations of Syndromic Surveillance (3)
• Costly– Infrastructure and staff– Complicated data use agreements
Surveillance Applications
Applications• Establish public health priorities• Aid in determining resource allocation• Assess public health programs
– Facilitate research
• Determine baseline level of disease• Detect epidemics
– Estimate magnitude of the problem– Determine geographical distribution
Establish Public Health Priorities
• Frequency – Incidence, prevalence,
mortality, years of life lost
• Severity – Case fatality rate,
hospitalization, disability
• Cost – Direct, indirect
Resource AllocationTUBERCULOSIS: Reported cases per 100,000 population, United States, 2010
Source: National TB Surveillance SystemMMWR March 25, 2011 / 60(11);333-337
1998-1999
1999-2000
2000-2001
2001-2002
2002-2003
2003-2004
2004-2005
2005-2006
2006-2007
2007-2008
2008-2009
2009-2010*
0
200
400
600
800
1000
1200
Year
Num
ber
of L
abor
ator
y C
onfir
med
C
ases
Assess Public Health ProgramsLaboratory Confirmed Cases of Meningitis C,
England and Wales, 1998 - 2010
Source: Health Protection Agency, Infectious Diseases, Meningitis, Epidemiologic Datahttp://www.hpa.org.uk/webw/HPAweb&HPAwebStandard/HPAweb_C/1234859709051?p=1201094595391
Determine Baseline RatesTB Case Rates in U.S.-born vs. Foreign-born
Persons United States, 1993–2009*
Cas
es p
er 1
00,0
00
*Updated as of July 1, 2010.
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
0
10
20
30
40
U.S.-born Foreign-born U.S. Overall
Early Detection of Epidemics0
5010
015
020
0N
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Number of flu patients by monthBoston, MA
Surveillance Limitations and Challenges
Surveillance Limitations (1)• Uneven application of information
technology – Paper-based versus electronic
• Timeliness– Reporting time requirement– Reporting burden
Surveillance Limitations (2)
• Completeness– Unreported cases– Incomplete reports– Consistency of reporting
CDC
Varied communications methods and security - specific to each system- including paper forms, diskettes, e-mail, direct modem lines, etc.
Current Situation
MMWR Weekly TablesMMWR Annual Summaries
Program Specific Reports and Summaries
State Health Dept
TIMSSTD*MIS
HARS
HARS STD*MIS TIMS NETSS EIP Systems
NETSS
STD*MIS (Optional at the Clinic)
TIMS (Optionalat the Clinic)
PHLISEIP Systems*
PHLIS
HARS STD*MIS
TIMS NNDSS EIP Systems
PHLIS
* EIP Systems (ABC, UD, Foodnet)
Data SourcesPhysicians
Varied communications methods and security - specific to each system - including diskettes, e-mail, direct modem lines, etc.
Chart Review
Lab Reports
Reporting by Paper Form, Telephone & Fax
Statistical Surveys for Chronic Diseases, Injuries and Other Public Health Problems
City/County Health Department
Limitations: Multiple Categorical Systems
National Electronic Disease Surveillance System (NEDSS)
• Not a traditional surveillance system
• Electronically integrates existing surveillance systems for easy data collection, storage and access
• Includes security measures to ensure confidentiality
• Allows data queries
Surveillance Challenges
• Assessing quality of the data
• Using case definitions
• Translating data into information
Quality of the Data
• Completeness of case ascertainment
• Assessment of completeness, accuracy, and timeliness of reports
‘Tip of the iceberg’
Diagnosis is reported
Diagnosis is made
Patients visit healthcare provider
Ill Patients
Surveillance Challenges by Definition
• Clinical vs. surveillance case definitions• Cases ‘worked’ vs. cases ‘counted’• Place of exposure, residence, or diagnosis• Re-infection or duplicate report• Frequencies by date of onset, date of
diagnosis, or date of report
Translating Data into Information
• Provides the basis for public health action
• Requires sound analysis and interpretation
• Extracts meaningful, actionable findings
• Requires clear presentation of complex issues
Summary• Public health surveillance is the ongoing
collection, analysis, interpretation of health data and dissemination of information
• Surveillance data are used for planning, implementation, and evaluation of public health practice
• Surveillance data collection can be passive, active, or syndromic; each type presents unique advantages and limitations
References and Resources• Bonetti M, et al. Syndromic Surveillance. Harvard Center for Public Health
Preparedness; August 2003. • Public Health Surveillance Program Office [Web page]. Centers for Disease
Control and Prevention. Available at: http://www.cdc.gov/osels/ph_surveillance/. Accessed March 1, 2012.
• State Electronic Disease Surveillance Systems --- United States, 2007 and 2010. MMWR Morb Mortal Wkly Rep. 2011;60(41):1421-1423. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6041a3.htm?s_cid=mm6041a3_w. Accessed March 1, 2012.
• Nationally Notifiable Conditions [Web page]. Division of Notifiable Diseases and Healthcare Information, Centers for Disease Control and Prevention. Available at: http://www.cdc.gov/osels/ph_surveillance/nndss/phs/infdis.htm. Accessed March 1, 2012.
References and Resources • Notifiable Diseases/Deaths in Selected Cities Weekly Information. MMWR
Morb Mortal Wkly Rep. 2004;53(21):460-468. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5321md.htm. Accessed March 1, 2012.
• Flamand C, Larrieu S, Couvy F, Jouves B, Josseran L, Filleul L. Validation of a Syndromic Surveillance System using General Practioner House Calls Network, Bordeaux, France. Eurosurveillance. 2008;13(25). Available at: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=18905. Accessed March 1, 2012.