Interpreting the data
What these data tell us:
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These data provide information about blood lead testing and blood lead levels among children born in the same year. A group of children all born in the same year is called a birth cohort. For example, all children born in 2007 and tested by their third birthday is a birth cohort.
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The birth cohort indicator evaluates screening practices and success at testing children before their third birthday. These data tell us how many children, born the same year, were tested for lead poisoning before their third birthday. These data, showing the screening rate, are available at the state level and for each county.
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These data give an estimate of how many children born in a certain year have lead poisoning. Lead poisoning is defined as a level of 3.5 or more micrograms of lead per deciliter of blood (≥3.5 µg/dL). This is the current CDC intervention level. These data include the number of confirmed blood lead tests, unconfirmed tests, and tests that are not considered elevated. The unconfirmed blood lead tests indicate the number of children who were lost to follow-up.
What these data do not tell us:
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They do not tell us the blood lead levels of all children in Colorado. CDPHE recommends testing only children who are at increased risk of lead poisoning.
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These data do not tell us what health effects, if any, have been experienced by children with a confirmed test.
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These data do not tell us how Colorado compares to other states. Childhood blood lead testing practices vary between states; some recommend universal testing, while others recommend targeted tested.
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Data may not allow for direct comparison between counties due to limitations such as variations in reporting practices.
Numerator/denominator information
Event/numerator data:
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Blood lead test results that are reported to CDPHE. If more than one test is reported for a child only one of the tests is used in the calculation.
Population/denominator data:
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Population estimates, State Demography Office, Colorado Department of Local Affairs.
Limitations of the data
Quality assurance activities have not been performed to determine the completeness of blood lead test reporting in Colorado. This means that we do not know how many records may be missing from this data set. On average, 20,000 to 30,000 blood lead test results are reported to CDPHE each year.
Approximately 10 percent of records reported do not have sufficient address information to assign county of residence. These records are included and listed as “unknown county”.
Denominator data are based on population estimates of the total number of children in a specific age category. This method overestimates the number of children targeted for lead testing in Colorado since we do targeted testing.
Data not included
Tests that are not processed through a lab or reported are not included in these data prior to August 2011. Point of care testing uses capillary blood specimens and ESA Lead Care II equipment. Approximately 40 clinics throughout Colorado use ESA equipment. Voluntary paper reporting began in August 2011 and those records are included beginning with 2011 data.
Calculation methods
- Number and percentage of children born in the same year and tested for lead before their third birthday.
- The number of children born in the same year who had a reported lead test before their third birthday, divided by the total number of children born in that year.
- Number and percentage of children born in the same year and tested for lead before their third birthday, with confirmed blood lead levels.
- The number of children born in the same year who had a confirmed blood lead test reported before their third birthday, divided by the number of children born in the same year who had any lead test reported before their third birthday.
- Number and percentage of children born in the same year and tested for lead before their third birthday, with unconfirmed blood lead levels.
- The number of children born in the same year who had an unconfirmed blood lead test reported before their third birthday, divided by the number of children born in the same year who had any lead test reported before their third birthday.
A blood lead level is considered elevated if the laboratory if the result is 3.5 µg/dL or more. A test is considered unconfirmed if only one capillary test is elevated within a 12 week period. If a report does not specify if a test was venous or capillary, it is treated as a capillary test. A poorly collected capillary test can be contaminated by lead in the environment. It is recommended that elevated capillary tests be confirmed with a venous test. Unconfirmed elevated tests are reported as an indicator of the number of children who are lost to follow-up.
Dataset information
This indicator is presented as:
- Numbers of children born in a certain year.
- Number of children born that year who are tested for lead before age 3 years.
- Percent of children born that year who are tested for lead before age 3 years.
- Number and percentage of those tests that are confirmed elevated by county of residence.
- Percent of children in each county who are five years old or younger and living below the federal poverty level. This is included because in Colorado blood lead testing is recommended for these children.
Data prepared by:
- Colorado Environmental Public Health Tracking, CDPHE.
Data source:
- Number of children born per year is provided by the Health Statistics Section of CDPHE.
- Number and percentage of children tested for lead before age 3 years and number.
- Percentage of confirmed blood lead tests provided by Colorado Environmental Public Health Tracking, CDPHE.