The Accuracy of a Lead Questionnaire in Predicting Elevated Pediatric Blood Lead Levels

Abstract

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 μmol/L (4.19 μg/dL). Eighty-five children had blood lead levels of 0.48 μmol/L (10 μg/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 μmol/L (20 μg/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 μmol/L (20 μg/dL) was $4925. Conclusions: Few of the low-income children in this study had blood lead levels greater than 0.48 μmol/L (10 μg/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. Arch Pediatr Adolesc Med. 1996;150:958-963