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The accuracy of a lead questionnaire in predicting elevated pediatric blood lead levels
E K France1, B A Gitterman, P Melinkovich
1Department of Community Health Services, Denver Health and Hospitals, Colo, USA.
Insights
In Denver, a study found low prevalence of elevated blood lead levels in urban children. Lead screening questionnaires were ineffective, performing no better than chance in identifying children with high lead levels.
Area of Science:
- Pediatric Environmental Health
- Public Health Surveillance
- Toxicology
Background:
- Elevated blood lead levels (BLLs) pose significant health risks to children.
- Accurate screening methods are crucial for early detection and intervention.
- Inner-city pediatric populations often face higher exposure risks.
Purpose of the Study:
- To determine the prevalence of elevated BLLs in a western United States urban inner-city pediatric population.
- To evaluate the diagnostic accuracy of a lead screening questionnaire compared to blood lead level testing.
Main Methods:
- A convenience sample of 2978 children (6 months to 6 years) underwent venous blood lead level testing.
- A lead screening questionnaire was administered to participants during well-child visits.
- Operating characteristics (sensitivity, specificity, PPV) of questionnaires were compared to criterion standard BLLs.
Main Results:
- The mean BLL was 0.20 µmol/L (4.19 µg/dL).
- 2.9% of children had BLLs ≥ 0.48 µmol/L (10 µg/dL).
- Questionnaires demonstrated low sensitivity and specificity, with poor predictive values (3% and 2.6% PPV).
Conclusions:
- The prevalence of elevated BLLs (≥ 0.48 µmol/L) was low in this low-income Denver pediatric cohort.
- Lead screening questionnaires were found to be unreliable for identifying children with elevated BLLs.
- Blood lead level testing remains essential for accurate childhood lead screening in this community.
Objectives:
To determine the prevalence of elevated blood lead levels and to evaluate the accuracy of a lead screening questionnaire in a western United States urban inner-city pediatric population.
Design:
A convenience sample of children between the ages of 6 months and 6 years seen for a well-child visit were enrolled. Venous blood lead levels were measured and a lead screening questionnaire was completed.
Setting:
The primary care clinics of the 10 community health centers of the city and county of Denver, Colorado. Approximately 85% of children receiving services are below the 150% poverty level and 54% are insured through the state's Medicaid program.
Subjects:
A total of 2978 children seen for a well-child visit from February 1993 to January 1994.
Main Outcome Measures:
The prevalence of elevated blood lead levels and the operating characteristics of both the Centers for Disease Control and Prevention lead screening questionnaire and the complete questionnaire used in Denver, using venous blood lead levels as the criterion standard.
Results:
The mean blood lead level was 0.20 mumol/L (4.19 micrograms/dL). Eighty-five children had blood lead levels of 0.48 mumol/L (10 micrograms/dL), representing 2.9% of the study group (95% confidence interval [CI], 2.3-3.5). Only 0.3% of the cohort had blood lead levels greater than 0.96 mumol/L (20 micrograms/dL). The sensitivity, specificity, and positive predictive value of the Centers for Disease Control and Prevention questionnaire was 57%, 51%, and 3%, respectively. The sensitivity, specificity, and positive predictive value of the complete questionnaire was 59.7%, 36%, and 2.6%, respectively. The marginal cost of identifying a child with a blood lead level greater than 0.96 mumol/L (20 micrograms/dL) was $4925.
Conclusions:
Few of the low-income children in this study had blood lead levels greater than 0.48 mumol/L (10 micrograms/dL). The questionnaire did little better than chance at predicting the presence or absence of elevated blood lead levels and cannot replace a blood lead level test for childhood lead screening in this community.