Development of a screening tool for prediction of children at risk for lead exposure in a midwestern clinical setting

OBJECTIVE

Universal screening for childhood lead poisoning is becoming quite common, with many states having legislation requiring screening. We set out to determine whether a questionnaire could be used to identify children at risk for exposure to lead to determine whether selective screening of those at risk was possible.

METHODS

Parents of 370 children 12 to 36 months of age having well-child examinations completed a questionnaire and their children were screened by a fingerstick capillary blood lead test at two clinics.

RESULTS

Of patients from clinic A, 5.4% had lead levels > or = 10 micrograms/dL compared with 16.8% of those from clinic B (P < .001). This difference between clinics could not be explained by the demographic characteristics of the patients or by differences in their potential exposures to lead. We evaluated the five questions suggested by Centers for Disease Control and Prevention for anticipatory guidance for their ability to identify children with elevated blood lead levels. In clinic A, this instrument had a sensitivity of 76.9% and a negative predictive value of 96.5%. In clinic B, it had a sensitivity of 63.6% and a negative predictive value of 81.4%. Based on an assessment of significant items from a large questionnaire, we determined five questions that were the best predictors of risk. On the basis of this risk assessment, 100% of the children from clinic A with elevated lead levels and 90.9% of the children from clinic B with elevated lead levels were classified as being at "high risk." Had this risk assessment been used as an initial screen in this sample, 40% of the patients from clinic A and 37% of the patients from clinic B would not have been screened with a blood lead test, because they were classified as being at "low risk."

CONCLUSIONS

Results of this study suggest that there is great variability in the prevalence of elevated lead levels and potential risks between clinics within a fairly homogeneous community; however, selective screening with a community-specific questionnaire may be feasible if the prevalence is low and the risks to the population are known.