Standard Surveillance Definitions and Classifications

CDC uses the following surveillance definitions for all states:

• Test: Any blood lead level sample (BLL) drawn (capillary, venous or unknown sample type) on a child that produces a quantifiable result and is analyzed by a CLIA-certified facility or an approved portable device. A blood lead test may be collected for screening, confirmation or follow-up.
• Screening test: A blood lead test for a child age <72 months who previously did not have a confirmed elevated BLL (NOTE: A child may be screened in multiple years or even multiple times within a given year, but would be counted only once for each year).
• Confirmed elevated BLL (EBLL): A child with one venous blood specimen ≥10 μg/dL, or any combination of two capillary and/or unknown blood specimens ≥10 μg/dL drawn within 12 weeks of each other.
• Percent of children with elevated blood lead levels: The number of children less than 72 months of age with a confirmed elevated blood lead level ≥10 µg/dL divided by the number of children less than 72 months of age tested for blood lead, multiplied by 100. Also referenced as “Case Rate.”
• Percent of children tested: The number of children less than 72 months of age tested for blood lead divided by the total number of children less than 72 months of age based on 2000 U.S. Census data, multiplied by 100. Also referenced as “Screening Rate.”

Classifications

To classify confirmed elevated BLLs, two elevated capillary or unknown tests (we assume unknown tests are capillary) must be drawn within 12 weeks (84 days).

Once a child has had one confirmed elevated BLL, if in subsequent years he or she has another elevated test result, regardless of the test type, we include that child in the tables showing the number of children with confirmed elevated BLLs for each year he or she continues to have an elevated BLL test result (prevalence data).

However, a child is counted only once for each year in which he or she is tested and has an elevated BLL. In a subsequent year, if a child with a confirmed elevated BLL has no follow-up test or only follow-up tests that are below 10 μg/dL, the child would not be counted with confirmed elevated BLLs for that year.