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SURVEILLANCE

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					PUBLIC HEALTH
SURVEILLANCE
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
 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
 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
 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
PURPOSES OF PUBLIC
HEALTH 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
 Evaluating hypotheses about the cause of health
  problems
 Detecting rate but important cases of diseases, such as
  botulism
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
TYPES OF SURVEILLANCE (cont’d.)

 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
TYPES OF SURVEILLANCE (cont’d.)

 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
TYPES OF SURVEILLANCE (cont’d.)

 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
THE BEHAVIORAL RISK FACTOR
SURVILLANCE 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
THE BEHAVIORAL RISK FACTOR
SURVILLANCE 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
     state’s survey coverage

				
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