The failure of CDC screening questionnaire to efficiently detect elevated lead levels in a rural population of children

BACKGROUND. In 1991, the Centers for Disease Control and Prevention (CDC) lowered the level for lead toxicity from 25 mu g/dL to 10 mu g/dL and published guidelines recommending that all children be tested for blood lead level at 12 months of age and again, if possible, at 24 months. The guidelines also called for periodic universal screening of children between the ages of 6 and 72 months using the CDC's lead screening questionnaire. However, blindly following these recommendations may result in unnecessary patient discomfort, wasted time, and extra expense. According to the CDC guidelines, deviation from this practice requires the determination of the local prevalence of lead poisoning. The purpose of this study was to measure the local prevalence of elevated blood lead levels (EBLL) and to assess the utility of the CDC's lead screening questionnaire in a rural setting. METHODS. Three hundred seventy-six children living on the Navajo Reservation in Arizona were studied. A consecutive series evaluation at well-child visits between the ages of 6 and 72 months was conducted using the CDC lead screening questionnaire and blood lead levels measured by anodic voltammetry. RESULTS. Of 376 children, 368 had their blood levels tested. Eight children tested positively with an EBLL of greater than or equal to 10 mu g/dL for a prevalence of 2.2%. Three hundred twenty-three completed questionnaires; 83 (25.7%) of these children had false-positive results. The sensitivity and specificity of the CDC lead screening questionnaire were 42.9% and 73.7%, respectively. The positive predictive value of the questionnaire was 3.5%. CONCLUSIONS. In this rural population of children, the prevalence of lead poisoning was low, and the CDC lead screening questionnaire failed to efficiently identify those children with lead toxicity Screening such a population using the CDC guidelines will result in unnecessary discomfort for children and will squander limited resources of time and money. Physicians who care for children should know the local prevalence of EBLL in order to effectively follow the CDC's recommendations for lead screening.