Session 4, Part 1 Introduction to Surveillance Learning Objectives Session 4, Part 1 • Explain the surveillance “feedback loop” of data and information flow.
Download ReportTranscript Session 4, Part 1 Introduction to Surveillance Learning Objectives Session 4, Part 1 • Explain the surveillance “feedback loop” of data and information flow.
Session 4, Part 1 Introduction to Surveillance Learning Objectives Session 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 Overview Session 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) Surveillance Flow • Physicians • Laboratories • STD clinics • Community health clinics • Emergency departments (EDs) Standardized data collection County and state health departments, CDC analyze data using statistical methods Surveillance Flow • Physicians Standardized data collection • Laboratories • STD clinics • Community health clinics County and state health departments, CDC analyze data using statistical methods Dissemination to those who need to know • EDs Dissemination to those who need to know • Public health officials • Health directors • Health policy officials Surveillance Flow • Physicians Standardized data collection • Laboratories • STD clinics • Community health clinics County and state health departments, CDC analyze data using statistical methods Dissemination to those who need to know • EDs 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 officials • Health directors • Health policy officials Surveillance Flow • Physicians Standardized data collection • Laboratories • STD clinics • Community health clinics County and state health departments, CDC analyze data using statistical methods Dissemination to those who need to know • EDs Public health evaluation Change in public health practice (vaccination, reduction of risk factors, medical intervention, etc.) Dissemination to those who need to know Public health planning and intervention • Public health officials • Health directors • Health policy officials 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 Passive Active 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 Lab Hospital Physician CDC State Local Health Department 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 Lab Hospital Physician CDC State Local Heath Department Active Surveillance Applications • Outbreak investigations • Other times when complete case ascertainment is desired – Research study – Incomplete information reported Advantages and Limitations Passive Surveillance Active Surveillance • Advantages – Inexpensive – Low data collection burden for health department • Advantages – Complete data – Flexible • Limitations – Under-reporting – Missing information – Can be slow • 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 Daily temperatures and GP visits for heat syndrome, Bordeaux, 1 June – 31 Aug, 2006 Source: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=18905 Common Syndromes Under 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 Allocation TUBERCULOSIS: Reported cases per 100,000 population, United States, 2010 Source: National TB Surveillance System MMWR March 25, 2011 / 60(11);333-337 Number of Laboratory Confirmed Cases Assess Public Health Programs 1200 1000 Laboratory Confirmed Cases of Meningitis C, England and Wales, 1998 - 2010 800 600 400 200 0 Year Source: Health Protection Agency, Infectious Diseases, Meningitis, Epidemiologic Data http://www.hpa.org.uk/webw/HPAweb&HPAwebStandard/HPAweb_C/1234859709051?p=1201094595391 Determine Baseline Rates Cases per 100,000 TB Case Rates in U.S.-born vs. Foreign-born Persons United States, 1993–2009* 40 30 20 10 0 1993 1995 1997 U.S.-born *Updated as of July 1, 2010. 1999 2001 Foreign-born 2003 2005 2007 U.S. Overall 2009 200 Early Detection of Epidemics Number of flu patients by month 0 50 100 N 150 Boston, MA Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 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 Limitations: Multiple Categorical Systems Current Situation Program Specific Reports and Summaries MMWR Weekly Tables MMWR Annual Summaries CDC HARS STD* MIS TIMS NNDSS EIP Systems PHLIS Statistical Surveys for Chronic Diseases, Injuries and Other Public Health Problems Varied communications methods and security - specific to each system - including diskettes, e-mail, direct modem lines, etc. State Health Dept HARS STD*MIS TIMS NETSS EIP Systems Reporting by Paper Form, Telephone & PHLIS Fax Data Sources Physicians Varied communications methods and security - specific to each system- including paper forms, diskettes, e-mail, direct modem lines, etc. Chart Review Lab Reports HARS City/County Health Department STD*MI S TIMS NETSS EIP Systems * PHLIS * EIP Systems (ABC, UD, Foodnet) STD*MIS (Optional at the Clinic) TIMS (Optional at the Clinic) 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 Diagnosis is reported Diagnosis is made Patients visit healthcare provider Ill Patients ‘Tip of the iceberg’ 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=mm60 41a3_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.