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 2007 Johns Hopkins Bloomberg School of Public Health Principles of Surveillance Jonathan Samet, MD, MS Johns Hopkins Bloomberg School of Public Health.

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Presentation on theme: " 2007 Johns Hopkins Bloomberg School of Public Health Principles of Surveillance Jonathan Samet, MD, MS Johns Hopkins Bloomberg School of Public Health."— Presentation transcript:

1  2007 Johns Hopkins Bloomberg School of Public Health Principles of Surveillance Jonathan Samet, MD, MS Johns Hopkins Bloomberg School of Public Health

2  2007 Johns Hopkins Bloomberg School of Public Health 2 Learning Objectives Define the basic terms related to surveillance Specify characteristics of surveillance systems for different objectives Describe selected major surveillance systems

3  2007 Johns Hopkins Bloomberg School of Public Health 3 Uses of Morbidity and Mortality Data 1.Hypothesis generation 2.Health planning 3.Program evaluation 4.Surveillance

4  2007 Johns Hopkins Bloomberg School of Public Health 4 Surveillance “Ongoing, systematic collection, analysis, and interpretation of health-related data essential to the planning, implementation, and evaluation of public health practice, closely integrated with the timely dissemination of these data to those responsible for prevention and control.” — U.S. Centers for Disease Control and Prevention

5  2007 Johns Hopkins Bloomberg School of Public Health 5 Information Loop of Public Health Surveillance Source: adapted by CTLT from

6  2007 Johns Hopkins Bloomberg School of Public Health 6 Immediate Detection of... Epidemics  Established agents  Emerging agents Newly emerging health problems Changes in health practices Changes in antibiotic resistance Chemical and biological terrorism Source: Thacker and Stroup. (1994).

7  2007 Johns Hopkins Bloomberg School of Public Health 7 Periodic Dissemination for... Estimating the magnitude of the health problem, including costs Assessing control activities Setting research priorities Testing hypotheses Facilitating planning Monitoring risk factors Monitoring changes in health practices Source: Thacker and Stroup. (1994).

8  2007 Johns Hopkins Bloomberg School of Public Health 8 Source: Thacker and Stroup. (1994). Archival Information for... Describing the natural history of disease Facilitating epidemiologic and laboratory research Validating the use of preliminary data Setting research priorities Documenting distribution and spread

9  2007 Johns Hopkins Bloomberg School of Public Health 9 Langmuir on Surveillance “Surveillance, when applied to a disease, means the continued watchfulness over the distribution and trends of incidence through the systematic collection, consolidation, and evaluation of morbidity and mortality reports and other relevant data.” — Alexander Langmuir

10  2007 Johns Hopkins Bloomberg School of Public Health 10 From Vector to Agent to Disease: Surveillance Points

11  2007 Johns Hopkins Bloomberg School of Public Health 11 Points for Surveillance Example: Tobacco

12  2007 Johns Hopkins Bloomberg School of Public Health 12 Modeling a Surveillance System Source: Teutsch and Churchill. (2000).

13  2007 Johns Hopkins Bloomberg School of Public Health 13 Surveillance Systems: Some Characteristics Geographic scale: local to global Event identification: active or passive Scope: all or sentinel events Focus on monitoring: vector  agent  outcome Purpose: tracking or alarm

14  2007 Johns Hopkins Bloomberg School of Public Health 14 Modeling a Surveillance System Source: Teutsch and Churchill. (2000).

15  2007 Johns Hopkins Bloomberg School of Public Health 15 Occurrence of an Event: Kind of Event What kind of an event?  Exposure  Exposure to air pollution, bio-monitoring  Disease  Communicable diseases, chronic diseases, syndromes  Injuries  Motor vehicle accidents, homicide  Health risk factors  Obesity  Health behaviors  Smoking, sexual behavior, substance use

16  2007 Johns Hopkins Bloomberg School of Public Health 16 What do you want to do a surveillance of?  Exposure  Agents  Biomarkers  Exposure determinants  Behaviors  Risk factors  Vectors  Host characteristics  Reservoirs  Health outcomes  Disease  Death  Medical care Occurrence of an Event: Surveillance of What?

17  2007 Johns Hopkins Bloomberg School of Public Health 17 WHO Global Tobacco Surveillance World Health Survey  Household survey of adults (18+) conducted in 70 countries in 2002–2003 STEPwise Approach to Surveillance (STEPS)  Modular survey of chronic disease risk factors Global Youth Tobacco Survey  School-based survey  Global Adult Tobacco Survey (planned)

18  2007 Johns Hopkins Bloomberg School of Public Health 18 Occurrence of an Event: What Type of System? What type of system would work best?  Universal: population tracking  Choose entire population or a representative sample to monitor for condition of interest (measles, obesity, bioterrorism agents)  Sentinel: “warning” signs  Choose key “location” to monitor for condition of interest (e.g., unusual disease)  “Locations” might include sites, events, providers, animals, vectors  Choose a “location” that is most susceptible to change

19  2007 Johns Hopkins Bloomberg School of Public Health 19 Capturing an Event: Approaches Active  Periodic solicitation of case reports from reporting sources, such as physicians, hospitals, laboratories, etc. Passive  Relies on health care providers to report on their own initiative  Must make this reporting process simple and time efficient

20  2007 Johns Hopkins Bloomberg School of Public Health 20 Active  Advantages  Can be very sensitive  Can collect more detailed information  May be more representative  Disadvantages  Costly  Labor intensive  Difficult to sustain over time Active vs. Passive: Advantages and Disadvantages Passive  Advantages  Less costly  Eager to design and carry out  Useful for monitoring trends over time  Disadvantages  Low sensitivity  Amount of data available is limited  May not be representative

21  2007 Johns Hopkins Bloomberg School of Public Health 21 Active: SEER Cancer Registry Source:

22  2007 Johns Hopkins Bloomberg School of Public Health 22 Passive: CDC Notifiable Diseases Provisional Cases of Selected Notifiable Diseases, United States, Week Ending July 16, 2005* Source: U.S. Centers for Disease Control. (2005). * Incidence data for reporting year 2005 is provisional Reporting Area AIDSChlamydia Cum. 2005Cum. 2004Cum. 2005Cum South Atlantic6,4736,02290,68791,830 Delaware100801,7291,514 Maryland ,69210,009 District of Columbia ,9701,910 Virginia ,55011,732 West Virginia36301,3501,493 North Carolina ,48515,198 South Carolina ,4339,891

23  2007 Johns Hopkins Bloomberg School of Public Health 23 Modeling a Surveillance System Source: Teutsch and Churchill. (2000).

24  2007 Johns Hopkins Bloomberg School of Public Health 24 Processing and Analyzing the Event How do you detect a signal? Data capture/editing/management Analytical approaches Statistical approaches

25  2007 Johns Hopkins Bloomberg School of Public Health 25 Examine the Event by Person, Place, and Time By person: demographics, lifestyle, risk factors By place: GIS mapping By time: epidemic curve, time series analysis

26  2007 Johns Hopkins Bloomberg School of Public Health 26 By Place: GIS Mapping GIS: geographic information systems  GIS links location to information (such as people to addresses, buildings to parcels, or streets within a network) and layers that information to give you a better understanding of how it all interrelates  You choose what layers to combine based on your purpose

27  2007 Johns Hopkins Bloomberg School of Public Health 27 Image source: adapted by CTLT from U.S. Centers for Disease Control and Prevention. (2005). By Time: Time Series Time series analysis accounts for the fact that data points taken over time may have an internal structure (such as trend or seasonal variation) that should be accounted for

28  2007 Johns Hopkins Bloomberg School of Public Health 28 By Person: Demographics Age Race/ethnicity Occupation Socioeconomic status Sex

29  2007 Johns Hopkins Bloomberg School of Public Health 29 By Place Small areas Governmental units Nations Unit chosen to examine is determined by the availability of data on particular geographic scales

30  2007 Johns Hopkins Bloomberg School of Public Health 30 Source: U.S. National Cancer Institute. (1999). Cancer Mortality Rates, by State

31  2007 Johns Hopkins Bloomberg School of Public Health 31 Heart Disease Death Rates: 1991–1995 Source: U.S. Centers for Disease Control and Prevention.

32  2007 Johns Hopkins Bloomberg School of Public Health 32 Male Lung Cancer Incidence Rate per 100,000 Source: adapted by CTLT from GLOBOCAN. (2002). IARC.

33  2007 Johns Hopkins Bloomberg School of Public Health 33 Female Lung Cancer Incidence Rate per 100,000 Source: adapted by CTLT from GLOBOCAN. (2002). IARC.

34  2007 Johns Hopkins Bloomberg School of Public Health 34 Modeling a Surveillance System Source: Teutsch and Churchill. (2000).

35  2007 Johns Hopkins Bloomberg School of Public Health 35 Disseminating the Information Process information for your audience  Broadcast faxes, , mailings to dissemination lists  Locally, to clinicians  Regionally, to health departments  Web sites  Journal articles  Media

36  2007 Johns Hopkins Bloomberg School of Public Health 36 Tobacco Use Information Systems Global InfoBase  Data repository for chronic disease risk factor prevalence, including tobacco use  Summarized in Surveillance of Risk Factors Report (SuRF) Global Information System on Tobacco Control (GISTOC)  Provides links to tobacco- related databases Image source: World Health Organization. (2003 and 2005).

37  2007 Johns Hopkins Bloomberg School of Public Health 37 World Health Organization: The SuRF Report Source: The World Health Organization.

38  2007 Johns Hopkins Bloomberg School of Public Health 38 Modeling a Surveillance System Source: Teutsch and Churchill. (2000).

39  2007 Johns Hopkins Bloomberg School of Public Health 39 Model for State-Based Chronic Disease Surveillance Response Hypothesis generation Health planning Program evaluation Source: Remington and Goodman. (1999).

40  2007 Johns Hopkins Bloomberg School of Public Health 40 Summary Surveillance takeaways  Ongoing collection  Systematic according to a plan  Results given to those who need to know them  Resulting action is based in evidence gained in the surveillance system


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