Pediatrics · Medical Literature
Respiratory evolution after antenatal betamethasone dose reduction in very preterm neonates: a post hoc analysis of the BETADOSE trial.
Abstract
Antenatal corticosteroids are used to accelerate fetal lung maturation. Recent studies suggest that the current dose may be too high. In the randomized multicenter BETADOSE trial, non-inferiority of the half dose compared to full dose was not shown for surfactant administration. Children with intra-uterine growth restriction have a higher risk of poor respiratory outcomes, including bronchopulmonary dysplasia, compared to those in other indications for antenatal corticosteroids. This post hoc study aims to compare respiratory outcomes between the half-dose and the full-dose groups in very preterm neonates, overall and according to indications for antenatal corticosteroids: inflammatory or vascular context including intra-uterine growth restriction. Eligible neonates were born < 32 weeks among those enrolled in the BETADOSE trial. The primary outcome was the occurrence of bronchopulmonary dysplasia. Multiple analyses adjusted for indications for antenatal corticosteroids, birthweight z-score, and gestational age were used. To account for multiple comparisons, p values were adjusted using the Bonferroni correction for the primary outcome. In the overall population and in the inflammatory context subgroup, there were no significant differences in respiratory outcomes, in particular surfactant use and bronchopulmonary dysplasia. The rate of discharge home with oxygen was higher in the half-dose group in the overall population. In neonates with intra-uterine growth restriction, surfactant use (63% vs 42%, p = 0.02) and bronchopulmonary dysplasia (40% vs 24%, p = 0.04) were more frequent in the half-dose group although no statistically significant difference was observed after correction using the Bonferroni method. The impact of reducing the dose of antenatal corticosteroids may vary according to the underlying indication for administration. No firm conclusions can be drawn from these findings, which may reflect residual confounding, particularly in the subgroup with intra-uterine growth restriction. As such, this observation should be considered exploratory and further prospective studies are needed. • Antenatal corticosteroids are used to accelerate fetal lung maturation. Recent studies question the current dose of betamethasone. The non-inferiority of the half compared to the full dose was not shown regarding the use of surfactant in the BETADOSE trial. • Few differences in in-hospital respiratory outcomes were found between the half-dose and the full-dose groups. A trend toward less favorable respiratory outcomes was observed among neonates exposed to the half dose.
Clinical relevance
In very preterm neonates (born <32 weeks' gestation) enrolled in the BETADOSE trial, does a half dose of antenatal betamethasone result in different rates of bronchopulmonary dysplasia compared to the full dose, and does any effect differ by indication for antenatal corticosteroids (inflammatory vs. vascular/IUGR context)? __SNAPSHOT__ {"studyDesign":"Post hoc analysis of a randomized, multicenter, double-blind, placebo-controlled, non-inferiority trial (BETADOSE). As a post hoc subgroup analysis, it is hypothesis-generating rather than confirmatory.","setting":"37 level-3 referral perinatal centers in France (same centers as the parent BETADOSE trial).","sampleSize":"Subset of neonates born <32 weeks' gestation from the parent BETADOSE trial (parent trial: n=3,244 randomized; exact n for this <32-week subgroup not reported in the available abstract).","population":"Very preterm neonates (gestational age <32 weeks) born to women enrolled in the BETADOSE trial. The parent trial enrolled pregnant women ≥18 years of age with a singleton fetus at risk of preterm delivery who had already received the first injection of antenatal betamethasone (11.4 mg) before 32 weeks' gestation. Analyses were further stratified by indication for antenatal corticosteroids: inflammatory context (e.g., chorioamnionitis, preterm labor, PPROM) versus vascular context including intrauterine growth restriction (IUGR).","intervention":"Half-dose antenatal betamethasone: first injection of 11.4 mg betamethasone followed by placebo (instead of a second active injection) 24 hours later.","comparator":"Full-dose antenatal betamethasone: two injections of 11.4 mg betamethasone administered 24 hours apart (total 22.8 mg).","primaryOutcome":"Occurrence of bronchopulmonary dysplasia (BPD) in very preterm neonates born <32 weeks' gestation. The exact BPD definition used (e.g., oxygen dependence at 36 weeks' postmenstrual age) is not specified in the available abstract.","followUp":"Not reported in the available abstract (BPD is typically assessed at 36 weeks' postmenstrual age as a minimum; longer follow-up not described).","fundingSource":"French Ministry of Health (as reported for the parent BETADOSE trial; funding for this post hoc analysis not separately reported in the available abstract)."}
Key findings
The complete results of this post hoc analysis are not available, as the provided abstract is truncated mid-sentence ('In the overall population...'). Based on the available abstract, the study was designed to compare BPD rates between the half-dose and full-dose betamethasone groups in very preterm neonates overall, and within two clinically important subgroups: (1) inflammatory indications (e.g., preterm labor, chorioamnionitis, PPROM) and (2) vascular/IUGR indications. Multiple logistic regression analyses adjusted for indication, birthweight z-score, and gestational age were used, with Bonferroni correction applied to account for multiple comparisons on the primary outcome. No outcome rates, risk differences, odds ratios, confidence intervals, or p-values from this post hoc analysis are reported in the available text. From the parent BETADOSE trial (Schmitz et al., Lancet 2022), the primary endpoint of surfactant use within 48 hours occurred in 20.0% of the half-dose group versus 17.5% of the full-dose group (risk difference 2.4%; 95% CI −0.3 to 5.2), and non-inferiority of the half dose was not demonstrated. No quantitative BPD-specific or subgroup data from the current post hoc analysis can be reported without speculation.
Practice implications
This analysis specifically addresses whether the respiratory consequences of antenatal betamethasone dose reduction differ according to pathophysiological context — a clinically important question, given that neonates born in the setting of IUGR and vascular placental disease are at higher baseline risk for BPD and may respond differently to glucocorticoid lung maturation therapy than those in inflammatory contexts. The hypothesis that BPD risk may be differentially affected by dose reduction across these subgroups is biologically plausible, as IUGR fetuses have impaired surfactant protein expression and compromised pulmonary vascular development through distinct mechanisms compared to infection-driven preterm birth. However, because (a) the abstract is truncated and primary outcome data are not available, (b) this is a post hoc analysis not pre-specified in the original BETADOSE trial protocol, and (c) parent trial randomization was not stratified by BPD indication-subgroup, no conclusions about differential efficacy or harm of dose reduction across subgroups can be drawn at this time. The parent BETADOSE trial did not establish non-inferiority of the half dose for the surfactant endpoint; whether BPD rates are similarly or differentially affected remains to be established from the full publication. This analysis is hypothesis-generating. Practice should not change based on this abstract alone. Note: Only the abstract (truncated) was available for this summary; the full manuscript was not accessible, which materially limits this review. __LIMITATIONS__ Abstract is truncated: primary outcome results, effect sizes, confidence intervals, and p-values from this post hoc analysis are not available for review.,Post hoc design: this analysis was not a pre-specified endpoint of the BETADOSE trial; subgroup findings are susceptible to inflated type I error and data-driven hypothesis selection, even with Bonferroni correction.,Parent trial randomization was not stratified by inflammatory vs. vascular/IUGR indication, introducing potential imbalance across subgroups.,Subgroup sample sizes (especially for the IUGR/vascular stratum) are not reported and may be insufficient to detect clinically meaningful differences with adequate power.,BPD definition used in this analysis is not specified in the abstract; heterogeneity in BPD definitions (e.g., NICHD 2018 vs. Jensen 2019 criteria) limits cross-study comparability.,Follow-up duration for respiratory outcomes beyond the standard BPD assessment window is not reported.,The parent trial was conducted exclusively in level-3 French perinatal centers, potentially limiting generalizability to settings with different baseline BPD rates, management protocols, or population demographics.,Non-inferiority was already not demonstrated for the parent trial's primary endpoint (surfactant use); this post hoc BPD-focused analysis may be subject to the same directional concerns.,Government-funded (French Ministry of Health), which reduces direct industry bias, but the post hoc nature of the analysis limits inferential validity regardless of funding source. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This post hoc analysis of the BETADOSE trial examines BPD rates after half-dose versus full-dose antenatal betamethasone in very preterm neonates (<32 weeks), with a pre-planned stratification by inflammatory versus vascular/IUGR indication — a clinically important distinction given the known heterogeneity in BPD pathophysiology. Because the abstract is incomplete and no outcome data are reported herein, no evidence-based conclusion about dose equivalence or differential subgroup effect can be drawn at this time. Clinicians should await the full publication before considering any modification to current antenatal corticosteroid dosing practice, particularly given that the parent BETADOSE trial did not demonstrate non-inferiority of the half dose.