Impact of pulse oximetry screening on the detection of duct dependent congenital heart disease: a Swedish prospective screening study in 39 821 newborns

Objective To evaluate the use of pulse oximetry to screen for early detection of life threatening congenital heart disease. Design Prospective screening study with a new generation pulse oximeter before discharge from well baby nurseries in West Gotaland. Cohort study comparing the detection rate of duct dependent circulation in West Gotaland with that in other regions not using pulse oximetry screening. Deaths at home with undetected duct dependent circulation were included. Setting All 5 maternity units in West Gotaland and the supraregional referral centre for neonatal cardiac surgery. Participants 39 821 screened babies born between 1 July 2004 and 31 March 2007. Total duct dependent circulation cohorts: West Gotaland n=60, other referring regions n=100. Main outcome measures Sensitivity, specificity, positive and negative predictive values, and likelihood ratio for pulse oximetry screening and for neonatal physical examination alone. Results In West Gotaland 29 babies in well baby nurseries had duct dependent circulation undetected before neonatal discharge examination. In 13 cases, pulse oximetry showed oxygen saturations <= 90%, and (in accordance with protocol) clinical staff were immediately told of the results. Of the remaining 16 cases, physical examination alone detected 10 (63%). Combining physical examination with pulse oximetry screening had a sensitivity of 24/29 (82.8%(95% CI 64.2% to 95.2%)) and detected 100% of the babies with duct dependent lung circulation. Five cases were missed (all with aortic arch obstruction). False positive rate with pulse oximetry was substantially lower than that with physical examination alone (69/39 821 (0.17%) v 729/38 413 (1.90%), P<0.0001), and 31/69 of the false positive cases with pulse oximetry had other pathology. Thus, referral of all cases with positive oximetry results for echocardiography resulted in only 2.3 echocardiograms with normal cardiac findings for every true positive case of duct dependent circulation. In the cohort study, the risk of leaving hospital with undiagnosed duct dependent circulation was 28/100 (28%) in other referring regions versus 5/60 (8%) in West Gotaland (P=0.0025, relative risk 3.36 (95% CI 1.37 to 8.24)). In the other referring regions 11/25 (44%) of babies with transposition of the great arteries left hospital undiagnosed versus 0/18 in West Gotaland (P=0.0010), and severe acidosis at diagnosis was more common (33/100 (33%) v 7/60 (12%), P=0.0025, relative risk 2.8 (1.3 to 6.0)). Excluding premature babies and Norwood surgery, babies discharged without diagnosis had higher mortality than those diagnosed in hospital (4/27 (18%) v 1/110 (0.9%), P=0.0054). No baby died from undiagnosed duct dependent circulation in West Gotaland versus five babies from the other referring regions. Conclusion Introducing pulse oximetry screening before discharge improved total detection rate of duct dependent circulation to 92%. Such screening seems cost neutral in the short term, but the probable prevention of neurological morbidity and reduced need for preoperative neonatal intensive care suggest that such screening will be cost effective long term.