Abstract
OBJECTIVE: This study was aimed to examine the relationship between duration of infant exposure to a moderate-to-large patent ductus arteriosus (PDA) shunt and the risk of developing bronchopulmonary dysplasia (BPD) or death before 36 weeks (BPD/death). STUDY DESIGN: Infants <28 weeks' gestation who survived ≥7 days (n = 423) had echocardiograms performed on day 7 and at planned intervals. RESULTS: In multivariable regression models, BPD/death did not appear to be increased until infants had been exposed to a moderate-to-large PDA for at least 7-13 days: OR (95%CI) (referent = closed or small PDA): moderate-to-large PDA exposure for <7 days: 0.38 (range, 0.10-1.46); for 7 to 13 days = 2.12 (range, 1.04-4.32); for ≥14 days = 3.86 (range, 2.15-6.96). Once the threshold of 7 to 13 days had been reached, additional exposure (≥14 days) did not significantly add to the increased incidence of BPD/death: (referent exposure = 7-13 days) exposure for 14 to 27 days = 1.34 (range, 0.52-3.45); for 28 to 48 days = 2.34 (range, 0.88-6.19); for ≥49 days = 1.80 (range. 0.59-5.47). A similar relationship was found for the outcome of BPD-alone. CONCLUSION: Infants < 28 weeks' gestation required at least 7 to 13 days of exposure to a moderate-to-large PDA before a significant increase in the incidence of BPD/death was apparent. Once this threshold was reached additional exposure to a moderate-to-large PDA did not significantly add to the increased incidence of BPD/death.