Using multivariable analysis, higher gestational age at birth (OR 2.6 95%CI 1.6–4.1) and non Caucasian ethnicity (OR 3.9 95%IC 1.5–10.1) (but not CYP genotype) were found to be statistically associated with the response to ibuprofen in extremely preterm neonates with PDA (Table 6). This evidence concerns the gene PPIG and Patent ductus arteriosus.