SURVEILLANCE AND MONITORING

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PUBLIC HEALTH SURVEILLANCE
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SURVEILLANCE AND MONITORING

• Health Surveillance -- the collection, analysis
  and interpretation of data on individuals or
  groups to detect the occurrence of certain events
  and their putative causes for (1) the purpose of
  prevention or control of certain diseases and
  other health conditions, (2) formulation of
  interventions, and (3) evaluation of the impact
  of programs
• Generally, surveillance requires three functions
  in this sequence (1) data collection, (2)
  analysis and interpretations, and (3) decision
  making

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• Surveillance may be performed using data from a
  variety of sources
• Mortality Data derived from death certificates
  and population censuses analyze by census tract
  characteristics such as geographic regions and
  socioeconomic status of the population
• Morbidity and Disability Data derived from
  regularly available sources such as hospitals,
  industry and schools. Morbidity and disability
  data may also be obtained via surveys of
  representative samples of populations -- e.g.,
  National Health Interview Survey, BRFSS

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• Specially Designed Data Sources such as cancer
  registries, which combine mortality and morbidity
  and serve many surveillance uses. For example,
  time trends for site-specific cancers, cancer
  control measures, new treatments, and the
  emergence of rare cancers may be identified and
  evaluated using cancer registries

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• Biologic Characteristics such as population
  growth, blood pressures, and nutritional status
  may also be the subject of surveillance -- e.g.,
  growth of school children made once a year and
  supplemented by additional information from
  students and parents on nutritional status,
  respiratory functions, etc. Allows comparison of
  such indicators as height and weight of
  equivalent age groups in successive calendar
  years as well as the comparison of annual growth
  rates of various age cohorts

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PURPOSES OF PUBLICHEALTH SURVEILLANCE

• Describing trends and the natural (secular)
  history of health problems
• Detecting epidemics
• Providing details about patterns of disease
• Monitoring changes in disease agents through
  laboratory testing
• Planning and setting health program priorities
• Evaluating the effects of prevention and control
  measures
• Detecting critical changes in health practices

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• Evaluating hypotheses about the cause of health
  problems
• Detecting rate but important cases of diseases,
  such as botulism

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TYPES OF SURVEILLANCE

• Four general categories of public health
  surveillance
• Passive Surveillance
• The most commonly practiced disease surveillance
  at state and local health departments --
  generally used standardized reporting cards or
  forms that are distributed in batches to
  hospitals, clinics, laboratories and other health
  care settings
• Passive surveillance usually targets physicians,
  laboratories, and infection control officers
• Referred to as passive because no action is taken
  unless completed reports are received by the
  public health agency and further public health
  action is deemed desirable
• Completeness of reporting is usually lowest for
  passive systems, but they tend to be the least
  expensive to maintain

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TYPES OF SURVEILLANCE (contd.)

• Active Surveillance
• Active surveillance involves an ongoing search
  for cases
• This may involve regular contacts with key
  reporting sources, such as telephone calls to
  physicians or laboratories, or a frequent review
  of data that may include cases of a specific
  condition, such as a review of laboratory logs
  for certain bacterial isolates or a review of
  admissions to burn units to identify severely
  burned individual
• Active surveillance systems may have high levels
  of completeness but are usually much more
  expensive to maintain some question the
  cost-effectiveness of active surveillance

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TYPES OF SURVEILLANCE (contd.)

• Sentinel Surveillance
• Sentinel surveillance involves the use of a
  sample of providers -- most generally, a sample
  of physicians or emergency rooms -- to identify
  trends in diseases that occur at relatively high
  frequencies
• E.g., sentinel surveillance systems, such as
  those for influenza, provide timely information
  about trends in influenza-like illness activitiy,
  and are useful for obtaining information about
  strains that may be circulating in a community --
  assuming that there is a laboratory-based
  component to the surveillance

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TYPES OF SURVEILLANCE (contd.)

• Special Surveillance System
• Special surveillance systems have been found
  useful for certain types of surveillance
  activities
• The Behavior Risk Factor Surveillance System
  (BRFSS) involves administering a questionnaire to
  a random sample of individuals on a ongoing basis
  to identify trends in behavior that affect health
  risk -- e.g., monitoring the impact of such
  activities as breast cancer screening with
  mammography, cervical cancer with pap smears, use
  of smoke alarms in houses, as well as other
  health-related behaviors and practices
• Mocrobiologic surveys have been useful in
  determining the antibioltic resistance among
  persons with invasive pneumococcal infections

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THE BEHAVIORAL RISK FACTORSURVILLANCE SYSTEM
(BRFSS)

• In 1981, the CDC began helping states and
  communities to survey adults, 19 years and older,
  by telephone about their health behaviors
• In 1984, the CDC initiated the BRFSS to enable
  states to collect state-specific behavioral risk
  factor data
• Data are used to estimate the prevalence of
  behaviors related to the leading causes of death
  and disability, and are available by such control
  variables as age, race, sex, income, and education

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THE BEHAVIORAL RISK FACTORSURVILLANCE SYSTEM
(BRFSS)

• By 1994, all 50 states and D.C. were
  participating in the BRFSS -- a telephone survey
  using random-digit dialing and a probability
  sample of U.S. householdsl
• The BRFSS survey instrument consists of
• Core questions asked in all states -- dealing
  primarily with recent or current behaviors that
  are risk factors for disease or injury and with
  quality of life indicators
• Standard modules -- sets of questions developed
  by the CDC on specific topics suggested by states
  -- each state decides every year which, if any,
  standard modules they will include
• State-specific questions -- included only in a
  particular states survey coverage