Reproducibility of the EL-Khuffash PDA severity score and PDA diameter measurements in extremely preterm infants

Background & aim: Almost all randomised controlled trials use a Patent Ductus Arteriosus (PDA) diameter ≥ 1.5 mm as the primary criterion to ascribe haemodynamic significance to the PDA. The aim of this study was to evaluate if calculation of a PDA Severity Score (PDAsc) possessed superior intra- and inter-rater reproducibility when compared with the measurement of PDA diameter alone.

Methods: This cross-sectional study assessed echocardiograms performed on infants <30 weeks gestation at 36 to 72 h of age between July 2020 and December 2022 to calculate the PDAsc. Intra-observer reproducibility of the PDA diameter and PDAsc were assessed by blinded repeated measurements performed by one investigator (AS) 4 weeks apart. One set of those measurements was compared with blinded measurements by another investigator (RM) to assess inter-rater reliability.

Results: Echocardiograms from 150 infants with mean ± SD gestation and birthweights of 26.5 ± 1.7 weeks and 903 ± 249 g respectively were examined. The PDAsc demonstrated near perfect agreement both within raters (Cohen's Kappa 0.97, p < 0.01) and between raters (Cohen's Kappa 0.94, p < 0.01) with regards to the threshold for treatment (a cut off ≥5.0). The PDA diameter threshold only demonstrated moderate agreement within raters (Kappa 0.57, p < 0.01) and between raters (Kappa 0.54, p < 0.01). In this cohort, 31 % of infants with a low risk PDAsc (< 5.0) also had a PDA diameter >1.5 mm.

Conclusion: Future RCTs for PDA treatment should strongly consider abandoning the use of PDA diameter in isolation as a criterion for recruitment into clinical trials.