Experience with physiological based cord clamping is associated with increased effect size: a post-hoc analysis of the ABC3 trial

Abstract

Background: A preplanned exploratory analysis of the ABC3 trial, performed in all 10 NICU centres in the Netherlands, evaluating the effect of physiological-based cord clamping (PBCC) on intact survival in very preterm infants, found a positive association between intact survival and experience with the PBCC approach. Objective: To evaluate the effect of PBCC on intact survival in preterm infants in centres with more experience with PBCC and in centres with less experience. Methods: A post-hoc secondary analysis was performed. Experienced and less experienced centres participating in the ABC3 trial included 669 infants born before 30 weeks of gestation, who were randomized to stabilization with intact cord and clamping after reaching cardiorespiratory stability (PBCC) or clamping after 30–60 s followed by stabilization (time-based delayed cord clamping (TBCC)). Centres were defined as “experienced” when: (1) caregivers were trained in the PBCC approach with evaluation of video and RFM recording; (2) experience in previous studies; (3) early initiation of ABC3 and (4) ≥20 % of inclusions. The primary outcome was intact survival (survival without major cerebral injury and/or necrotizing enterocolitis (NEC)). Outcomes were adjusted for differences in baseline characteristics. Results: Two centres were classified as “experienced” and the other eight as “less-experienced”, and included 43.1 % and 56.9 % of infants respectively. In experienced centres, intact survival was higher after PBCC compared with TBCC (72 % vs. 59 %; aOR 1.93 (95 %CI 1.73–2.17, P < 0.001)), with lower mortality (10 % vs. 20 %; aOR 0.40 (95 % CI 0.25–0.63, P < 0.001)). In less experienced centres, intact survival was not different (72 % vs. 75 %; aOR 0.94 (95 % CI 0.64–1.39, P = 0.93)), with higher mortality (16 % vs. 9.1 %; aOR 1.92 (95 % CI 1.05–3.50, P = 0.03)). Conclusions: PBCC was associated with increased intact survival in centres that had more previous experience and exposure to PBCC, but not in centres with less experience. We recommend that the effect of experience and training for new approaches should be taken into consideration in future studies on PBCC.