Pulse Oximetry Screening for Congenital Heart Defects in Newborn Infants (Pulseox): A Test Accuracy Study EDITORIAL COMMENT

The 2 methods used to screen for congenital heart defects (CHDs) are midtrimester ultrasonography and postnatal examination. Both fail to identify all cases of life-threatening defects. As result, a substantial number of infants with undetected CHDs are discharged from hospitals. Pulse oximetry is a well-recognized noninvasive objective test for quantification of hypoxemia. Although numerous studies have investigated the test as a screening method for CHDs, its diagnostic accuracy remains unclear because of problems with methodology and the small patient numbers in most studies. The aim of this prospective cohort study was to evaluate the diagnostic accuracy of pulse oximetry as a screening test for CHDs in newborn infants. Between 2008 and 2009, asymptomatic newborn babies (>34 weeks gestation) delivered at 6 maternity units in the United Kingdom were screened with pulse oximetry before discharge. Infants suspected of having CHDs after midtrimester ultrasound were also included in the study. Babies with abnormal oxygen saturations (not achieving predetermined thresholds) were classified as test-positive and underwent echocardiography. After discharge, all infants with normal pulse oximetry thresholds were followed clinically for 12 months using congenital anomaly registries. The primary study outcome was diagnostic accuracy (sensitivity and specificity) for detection of critical cases (those causing death or requiring invasive intervention within 28 days of birth) or serious congenital heart disease (those causing death or requiring invasive intervention within the first year of life). A total of 20,055 newborn babies were screened; of these, 53 (0.8%) had major congenital heart disease (24 critical and 29 serious). This corresponds to a prevalence of 2.6 per 1000 live births. The data showed that in asymptomatic infants, pulse oximetry had a sensitivity of 75% for critical lesions and 49% for all serious lesions (95% confidence interval [CI], 53.29-90.23 and 35.06-63.16, respectively). Exclusion of the 35 cases in the cohort already suspected of having CHDs after antenatal ultrasound reduced the sensitivity for critical cases to 58% (95% CI, 28%-85%) and for serious cases to 29% (95% CI, 15%-46%). The false-positive rate was 0.84% (169/20,055); specificity was 99.16%, with a 95% CI of 99.02-99.28. Among these 169 "false-positive" cases, 6 actually had significant CHDs (not in the critical or serious categories) and another 40 had respiratory or infective illnesses requiring urgent intervention. These findings show that pulse oximetry is a safe and feasible test with better sensitivity than clinical examination. This test adds value to the usual screening methods including antenatal ultrasound by identifying cases of critical CHDs that would otherwise be undetected.