Preterm Thrombocytopenia and Delay of Ductus Arteriosus Closure

To evaluate whether preterm thrombocytopenia within 24 hours of birth is associated with delayed closure of patent ductus arteriosus (PDA) and higher proportion of hemodynamically significant PDA (Hs-PDA).

Neonates (gestation 26^0/7-33^6/7 weeks, age <24 hours) with known platelet count and PDA on echocardiogram were prospectively enrolled. Asphyxia, congenital infections, structural heart disease, major malformations and clinical sepsis were exclusions. Subjects were recruited in groups A (n = 35), B (n = 18), and C (n = 17) [platelet counts >150,000, 100,000-150,000 and <100,000 per μL respectively] and underwent daily echocardiography until first closure of PDA, death, or day 10.

The primary outcome was time to first closure of PDA. Secondary outcomes included proportion with PDA at 72 hours and 7 days, Hs-PDA, and PDA needing treatment. In groups A, B, and C, median (first-third quartile) platelet counts (×100000/μL) were 2.28 (1.94-3.19), 1.25 (1.14-1.37), and 0.68 (0.54-0.83) and time to PDA closure was 2 (2-2), 2 (2-3), and 10 (6-10) days, respectively (log-rank test, P < .001). On Cox proportional hazard regression, platelet count (in multiples of 10 000 /μL) independently predicted time to PDA closure (adjusted hazard ratio: 1.045; 95% confidence interval: 1.019-1.07). On day 7, 47.1% neonates in group C had PDA and none in groups A and B (P < .001).

Thrombocytopenia within 24 hours of birth independently predicts delayed PDA closure and PDA on day 7 in preterm neonates.