Assessment of different thresholds of birthweight discordance in early
neonatal outcomes among twins: retrospective analysis of 2348 twin pregnancies
Abstract
Objective: To evaluate the thresholds of BWD for predicting early
neonatal outcomes and assess the predictive accuracy of BWD. Design:
Retrospective cohort study. Setting: Single Chinese University Hospital.
Population: All women with liveborn twins at gestational age of ≥ 26
weeks. Methods: Multivariable logistic regression analyses of
association between neonatal outcomes and BWD with different thresholds
(≥15.0%, ≥20.0%, ≥25% and ≥30%). Generalized estimated equation
(GEE) models to address inter-twin correlation. Restrictive cubic spline
(RCS) models to draw the dose-response relationship. Clustered receiver
operating characteristic (ROC) curve analysis to assess the predictive
accuracy. Main outcomes: NICU admission, neonatal respiratory distress
syndrome (NRDS), ventilator support and composite outcome including
major morbidity and neonatal death. Results Among 2348 twin pairs, BWD
were at significantly increased risks of NICU admission, irrespective of
the thresholds. The risks of NRDS, ventilator support and composite
outcome were significantly higher when a threshold of ≥20% or above was
chosen. The dose-response relationship showed non-linear growth in risk
of adverse neonatal outcomes with the increasing BWD. ROC analyses
showed a low significant AUROC of 0.569 (95% CI: 0.526-0.612) for
predicting NICU admission but no significant AUROC for predicting other
outcomes. A BWD of ≥30% provided a moderate increase in the likelihood
of NICU admission [positive likelihood ratio (LR+) =5.77].
Conclusions BWD is independently associated with adverse neonatal
outcomes. Regardless of this association, BWD could not serve as a
single predictor for neonatal outcomes. A cut-off of 30% is more
practical for risk stratification among twin gestations.
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