The Validity of Phosphatidylethanol in Dried Blood Spots of Newborns for the Identification of Prenatal Alcohol Exposure

Abstract

Accurate identification of prenatal alcohol exposure (PAE) in the newborn period offers an opportunity for early identification of children at risk of future neurocognitive problems and the implementation of interventional approaches earlier in life. PAE newborn screening by measuring phosphatidylethanol in dried blood spot (PEth-DBS) cards is feasible, logistically easier, and more cost-efficient compared with other biomarkers. However, the sensitivity and specificity of this method have yet to be established. This prospective cohort study examined validity of PEth-DBS among 28 infants with PAE and 32 controls relative to maternal self-report and other biomarkers. Pregnant women were recruited from a University of New Mexico clinic and followed to early postpartum period. The composite index, which was based on self-reported measures of alcohol use and allowed to classify subjects into PAE and control groups, was the criterion measure used to estimate sensitivity and specificity of PEth-DBS. The study included large proportions of patients representing ethnic minorities (7.4% American Indian, 81.7% Hispanic/Latina), low education (54.2% <high school), and unplanned pregnancy (90.0%). No differences in sociodemographic characteristics, smoking or illicit drug use were observed among the study groups. The sensitivity of maternal biomarkers (gamma glutamyltranspeptidase [GGT], % carbohydrate-deficient transferrin [%CDT], urine ethyl glucuronide [UEtG], urine ethyl sulfate [UEtS]) was low (<15%) reflecting a moderate chronic or intermittent binge pattern of drinking in this cohort. PEth-DBS demonstrated 100% specificity and the highest sensitivity (32.1%) compared with other biomarkers. A battery consisting of maternal direct ethanol metabolites (UEtG, UEtS, PEth) and newborn PEth-DBS increased sensitivity to 50% without a substantial drop in specificity (93.8%). Newborn PEth-DBS is a highly specific biomarker and can facilitate accurate detection of PAE in conjunction with other biomarkers. Minimal invasiveness, ease of storage and transportation of DBS cards, absence of postcollection synthesis, cost savings, and potential integration with routine newborn screening are all unique advantages of this method.