Review for 10.1186/s12876-025-03788-0 (2025)

Title: The effectiveness of treatment with probiotics in preventing necrotizing enterocolitis
and related mortality: Results from an umbrella meta-analysis on meta-analyses of randomized
controlled trials
Version: 2 Date: 03 Mar 2025
Reviewer:  Hongyi Li
Reviewer's report:
General Comments:
This umbrella meta-analysis synthesizes evidence on probiotics’ efficacy in preventing
necrotizing enterocolitis (NEC) and related mortality in preterm infants. The study is timely and
clinically relevant, given the high morbidity and mortality burden of NEC. The methodology
aligns with stringent guidelines (JBI, AMSTAR2), and findings broadly support probiotics’
benefits, particularly multi-strain formulations. However, several areas require clarification,
methodological refinement, and deeper discussion to strengthen the manuscript.
Major Comments:
1.The search is noted to extend up to August 2024, which appears to be an error. Clarify the
correct end date (e.g., August 2023) to ensure transparency and reproducibility.
2.The PICOS framework specifies preterm infants (<37 weeks or <1500 g). However, subgroup
analyses reference infants with "gestational age >37 weeks" and "weight <2500 g," conflicting
with inclusion criteria. Reconcile these discrepancies and ensure subgroup definitions align with
neonatal classifications (e.g., very preterm: <32 weeks, extremely preterm: <28 weeks).
3.While heterogeneity is acknowledged (e.g., I²=66.2% for NEC based on RR), the clinical
implications of such variability (e.g., differences in probiotic regimens, dosing, neonatal care
practices across regions) are underdeveloped. Expand on how these factors might influence
results and propose strategies for standardizing probiotic protocols in future trials.
4.The Discussion attributes multi-strain efficacy to "diverse bacterial composition" but lacks
integration with mechanistic evidence (e.g., synergistic interactions between Lactobacillus and
Bifidobacterium cited in references). Explicitly link findings to recent studies on strain-specific
effects (e.g., SCFA production, immune modulation) to strengthen biological plausibility.
5.Probiotics are cited as GRAS by the FDA, but recent concerns about probiotic safety in
immunocompromised preterm infants (e.g., sepsis risk from Lactobacillus or Bifidobacterium
strains) are omitted. Address this limitation by reviewing safety profiles from included studies
(e.g., incidence of adverse events) and discussing clinical guidelines for strain selection and
monitoring.
Minor Comments:
1.Use consistent terminology (e.g., "meta-analyses" vs. "studies" in Results). Clarify whether
"32 arms" refers to probiotic interventions or trials.
The introduction’s transition from NEC epidemiology to probiotics is abrupt. Add a sentence
summarizing current gap in probiotic evidence (e.g., conflicting meta-analyses) to justify the
umbrella review.
2.A majority of included studies are from China (12/35) and Australia (6/35). Discuss potential
geographic biases (e.g., variations in neonatal care practices, probiotic formulations) and their
implications for generalizability.
3.Some results lack precision: e.g., "p<0.00" (p.5). Verify statistical values (e.g., p<0.001).
Report pooled sample sizes for mortality analyses (currently only stated for NEC).
4.Figures 1–3B and supplementary materials are referenced but not included. Verify labeling
and ensure alignment with text descriptions (e.g., funnel plot asymmetry).
5.The conclusion emphasizes multi-strain probiotics but does not address unresolved questions
(e.g., optimal strains, dosage, duration). Add recommendations for future research to guide
clinical implementation.
This study makes a valuable contribution by consolidating conflicting evidence on probiotics
and NEC prevention. Addressing the methodological and interpretive issues above will enhance
rigor and clinical applicability. With revisions, this work has the potential to inform neonatal
care guidelines worldwide.