Table 13.1.

Possible sources of health indicator surveillance data

Data source	Pros	Cons and confounders
Outpatient and emergency department visits	Reflects incidence of disease in the general population	Nonspecific – may be difficult to document definitive information
Intensive care unit diagnoses	Best indicator of rare events like west Nile virus or Hantavirus pulmonary syndrome	Will not capture milder cases
Over-the-counter pharmacy sales	Reflects symptomatology most broadly	Subject to promotions/sales
Clinical lab submissions	Ordered by clinicians	May not be ordered for all (most) patients
Medicare or medicaid claims	Ease of capture data	Problems with timeliness and accuracy
Nursing homes	Reported by medical personnel; immobile population with limited exposure possibilities	Immobility reduces exposure potential; not broadly representative
Systematic testing for specific disease agents in specimens submitted to public health lab	Specificity of diagnoses	Broad screening not likely to capture meaningful data; difficulty getting information on positive samples; not timely
School and work absenteeism	May occur earlier than clinician visits	Nonspecific; delays in obtaining data
Ambulance call chief complaints	Many communities with timely access to data	Nonspecific
Poison information center calls	Ability to access in real-time	Many not be related to infectious diseases
HMO/nurse hotline calls	Occur very early in outbreak	May be difficult to categorize

Reprinted with permission from Biological Threats and Terrorism: Assessing the Science and Response Capabilities: Workshop Summary © 2002 by the National Academy of Sciences, courtesy of the National Academies Press, Washington, D.C.