Screening for lead poisoning by fingerstick in suburban pediatric practices
D. J. Schonfeld, P. M. Rainey, M. R. Cullen, D. R. Showalter and D. V. Cicchetti
Department of Pediatrics, Yale University School of Medicine, New Haven, Conn., USA.
OBJECTIVE: To assess the false-positive rate of blood lead determinations
on samples obtained by fingerstick from children screened in private
suburban and rural practices. METHODS: Screening capillary lead samples
were obtained by fingerstick; children with capillary lead levels of 0.7
mumol/L (15 micrograms/dL) or greater were recalled for a confirmatory
venous lead test that served as the criterion standard. Parents completed a
five-question risk assessment questionnaire at the time of initial
screening. SETTING: Four private suburban to rural practices that 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 lead level was 0.7
mumol/L (15 micrograms/dL) or greater in 35 children (3% of total sample);
venous lead samples were obtained in 30 patients. Nine 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 mumol/L [15, 17, 17, 18, 18, 18, 22, 22,
and 35 micrograms/dL]); parents of only two of these children answered yes
to any question on the risk assessment questionnaire. Although the
false-positive rate of the capillary lead screening test was 70% (21/30) in
this setting, only 2% of the total sample had a false-positive screening
test (an average of fewer than one false-positive per month per practice).
Screening by fingerstick allowed phlebotomy to be avoided for 97% of the
children. CONCLUSION: Fingerstick screening for lead poisoning is a
reasonable alternative to direct venous testing within private suburban and
rural practices, provided that care is taken to avoid specimen
contamination, that appropriate caution is used in the interpretation of
screening test results, and that medical and environmental interventions
are based on the results of confirmatory venous testing.
