SCREENING FOR LEAD-POISONING BY FINGERSTICK IN SUBURBAN PEDIATRIC PRACTICES

Objective: To assess the false-positive rate of blood lead determinati ons on samples obtained by fingerstick from children screened in priva te suburban and rural practices. Methods: Screening capillary lead sam ples were obtained by fingerstick; children with capillary lead levels of 0.7 mu mol/L (15 mu g/dL) or greater were recalled for a confirmat ory venous lead test that served as the criterion standard. Parents co mpleted a five-question risk assessment questionnaire at the time of i nitial screening. Setting: Four private suburban to rural practices th at serve predominantly white, middle-class populations. Participants: Children seen for routine care between August 1992 and February 1993 ( N=1085; 98% between 6 months and 6 years of age). Results: Capillary l ead level was 0.7 mu mol/L (15 mu g/dL) or greater in 35 children (3% of total sample); venous lead samples were obtained in 30 patients. Ni ne of the elevated capillary lead results were true-positives (venous lead=0.7, 0.8, 0.8, 0.9, 0.9, 0.9, 1.1, 1.1, and 1.7 mu mol/L [15, 17, 17, 18, 18, 18, 22, 22, and 35 mu g/dL]); parents of only two of thes e children answered yes to any question on the risk assessment questio nnaire. Although the false-positive rate of the capillary lead screeni ng test was 70% (21/30) in this setting, only 2% of the total sample h ad a false-positive screening test (an average of fewer than one false -positive per month per practice). Screening by fingerstick allowed ph lebotomy to be avoided for 97% of the children. Conclusion: Fingerstic k screening for lead poisoning is a reasonable alternative to direct v enous testing within private suburban and rural practices, provided th at care is taken to avoid specimen contamination, that appropriate cau tion is used in the interpretation of screening test results, and that medical and environmental interventions are based an the results of c onfirmatory venous testing.