Agreement between study designs: a systematic review comparing observational studies and randomized trials of surgical treatments for necrotizing enterocolitis

Prevention Strategies and Management of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a serious intestinal disease which primarily affects preterm infants. The pathogenesis of NEC is multifactorial. Thus, it is complicated to study, prevent, and manage.

Purpose of Review

The purpose of this review is to provide a comprehensive summary of recent research and provide recommendations for the prevention and management of NEC. Currently, management is supportive and non-specific and long-term outcomes for surgical NEC are poor.

Recent Findings

The most important strategy to prevent NEC is to provide preterm infants with a human milk diet, minimize exposure to antibiotics and avoid medications that disturb the intestinal microbiome.

Summary

Strategies to optimize the infant's intestinal microbiome are critical, as disturbances in the intestinal microbiome composition are a major factor in the pathogenesis of this disease. Optimizing maternal health is also vital to prevent prematurity and neonatal morbidity. Ongoing research holds promise for the implementation of new diagnostic modalities, preventive strategies, and medical treatment options to improve outcomes for premature infants.

Healthcare outcomes assessed with observational study designs compared with those assessed in randomized trials: a meta-epidemiological study

BACKGROUND

Researchers and decision-makers often use evidence from randomised controlled trials (RCTs) to determine the efficacy or effectiveness of a treatment or intervention. Studies with observational designs are often used to measure the effectiveness of an intervention in 'real world' scenarios. Numerous study designs and their modifications (including both randomised and observational designs) are used for comparative effectiveness research in an attempt to give an unbiased estimate of whether one treatment is more effective or safer than another for a particular population. An up-to-date systematic analysis is needed to identify differences in effect estimates from RCTs and observational studies. This updated review summarises the results of methodological reviews that compared the effect estimates of observational studies with RCTs from evidence syntheses that addressed the same health research question.

OBJECTIVES

To assess and compare synthesised effect estimates by study type, contrasting RCTs with observational studies. To explore factors that might explain differences in synthesised effect estimates from RCTs versus observational studies (e.g. heterogeneity, type of observational study design, type of intervention, and use of propensity score adjustment). To identify gaps in the existing research comparing effect estimates across different study types.

SEARCH METHODS

We searched MEDLINE, the Cochrane Database of Systematic Reviews, Web of Science databases, and Epistemonikos to May 2022. We checked references, conducted citation searches, and contacted review authors to identify additional reviews.

SELECTION CRITERIA

We included systematic methodological reviews that compared quantitative effect estimates measuring the efficacy or effectiveness of interventions tested in RCTs versus in observational studies. The included reviews compared RCTs to observational studies (including retrospective and prospective cohort, case-control and cross-sectional designs). Reviews were not eligible if they compared RCTs with studies that had used some form of concurrent allocation.

DATA COLLECTION AND ANALYSIS

Using results from observational studies as the reference group, we examined the relative summary effect estimates (risk ratios (RRs), odds ratios (ORs), hazard ratios (HRs), mean differences (MDs), and standardised mean differences (SMDs)) to evaluate whether there was a relatively larger or smaller effect in the ratio of odds ratios (ROR) or ratio of risk ratios (RRR), ratio of hazard ratios (RHR), and difference in (standardised) mean differences (D(S)MD). If an included review did not provide an estimate comparing results from RCTs with observational studies, we generated one by pooling the estimates for observational studies and RCTs, respectively. Across all reviews, we synthesised these ratios to produce a pooled ratio of ratios comparing effect estimates from RCTs with those from observational studies. In overviews of reviews, we estimated the ROR or RRR for each overview using observational studies as the reference category. We appraised the risk of bias in the included reviews (using nine criteria in total). To receive an overall low risk of bias rating, an included review needed: explicit criteria for study selection, a complete sample of studies, and to have controlled for study methodological differences and study heterogeneity. We assessed reviews/overviews not meeting these four criteria as having an overall high risk of bias. We assessed the certainty of the evidence, consisting of multiple evidence syntheses, with the GRADE approach.

MAIN RESULTS

We included 39 systematic reviews and eight overviews of reviews, for a total of 47. Thirty-four of these contributed data to our primary analysis. Based on the available data, we found that the reviews/overviews included 2869 RCTs involving 3,882,115 participants, and 3924 observational studies with 19,499,970 participants. We rated 11 reviews/overviews as having an overall low risk of bias, and 36 as having an unclear or high risk of bias. Our main concerns with the included reviews/overviews were that some did not assess the quality of their included studies, and some failed to account appropriately for differences between study designs - for example, they conducted aggregate analyses of all observational studies rather than separate analyses of cohort and case-control studies. When pooling RORs and RRRs, the ratio of ratios indicated no difference or a very small difference between the effect estimates from RCTs versus from observational studies (ratio of ratios 1.08, 95% confidence interval (CI) 1.01 to 1.15). We rated the certainty of the evidence as low. Twenty-three of 34 reviews reported effect estimates of RCTs and observational studies that were on average in agreement. In a number of subgroup analyses, small differences in the effect estimates were detected: - pharmaceutical interventions only (ratio of ratios 1.12, 95% CI 1.04 to 1.21); - RCTs and observational studies with substantial or high heterogeneity; that is, I2 ≥ 50% (ratio of ratios 1.11, 95% CI 1.04 to 1.18); - no use (ratio of ratios 1.07, 95% CI 1.03 to 1.11) or unclear use (ratio of ratios 1.13, 95% CI 1.03 to 1.25) of propensity score adjustment in observational studies; and - observational studies without further specification of the study design (ratio of ratios 1.06, 95% CI 0.96 to 1.18). We detected no clear difference in other subgroup analyses.

AUTHORS' CONCLUSIONS

We found no difference or a very small difference between effect estimates from RCTs and observational studies. These findings are largely consistent with findings from recently published research. Factors other than study design need to be considered when exploring reasons for a lack of agreement between results of RCTs and observational studies, such as differences in the population, intervention, comparator, and outcomes investigated in the respective studies. Our results underscore that it is important for review authors to consider not only study design, but the level of heterogeneity in meta-analyses of RCTs or observational studies. A better understanding is needed of how these factors might yield estimates reflective of true effectiveness.

Outcome Reporting in Interventional Necrotizing Enterocolitis Studies: A Systematic Review

BACKGROUND

Despite an increasing necrotizing enterocolitis (NEC) incidence, treatment strategies have failed to make major advancements towards improved NEC outcomes. Heterogeneity in outcome reporting and a lack of treatment efficacy studies potentially hamper these advancements. We aimed to analyze outcome reporting in recent interventional NEC studies.

METHODS

We performed a systematic review identifying interventional studies on NEC between 1st of January 2016 and 1st of June 2023 in MEDLINE, Embase, CENTRAL and Cochrane reviews. Systematic reviews, clinical trials and change-in-practice cohort studies reporting any therapeutic intervention for NEC patients (Bell's stage ≥ IIa) were eligible. We excluded studies on NEC diagnostics or prevention and non-English publications. Outcomes were categorized into five core areas and presented descriptively. The review was registered with PROSPERO (CRD42022302712).

RESULTS

Out of 1.642 screened records, 65 were eligible for full-text review and 15 were finally included for data extraction. Median number of reported outcomes per article was six (range 1-19). We identified 66 unique outcomes, which were mapped to 53 outcome terms. Thirty-four out of the 53 of the outcome terms (64%) were only reported in a single article. Mortality was the most reported outcome (11/15 articles, 73%). Core area 'Adverse outcomes' contained the most outcome terms (n = 19), whereas 'Life impact' contained the least outcome terms (n = 4) and was represented in 3 articles (20%).

CONCLUSIONS

Considerable heterogeneity in outcome reporting and a paucity of outcomes concerning 'Life impact' exist in interventional NEC studies. Development of a NEC core outcome set may improve consistency and patient-relevance in outcome reporting.

STUDY TYPE

Systematic Review and Meta-Analyses.

LEVEL OF EVIDENCE

III.

A Nomogram for Predicting Surgical Timing in Neonates with Necrotizing Enterocolitis

OBJECTIVE

To explore the surgical risk variables in patients with necrotizing enterocolitis (NEC) and develop a nomogram model for predicting the surgical intervention timing of NEC.

METHODS

Infants diagnosed with NEC were enrolled in our study. We gathered information from clinical data, laboratory examinations, and radiological manifestations. Using LASSO (least absolute shrinkage and selection operator) regression analysis and multivariate logistic regression analysis, a clinical prediction model based on the logistic nomogram was developed. The performance of the nomogram model was evaluated using the receiver operating characteristic (ROC) curve, calibration curves, and decision curve analysis (DCA).

RESULTS

A surgical intervention risk nomogram based on hypothermia, absent bowel sounds, WBC > 20 × 10⁹/L or < 5 × 10⁹/L, CRP > 50 mg/L, pneumatosis intestinalis, and ascites was practical, had a moderate predictive value (AUC > 0.8), improved calibration, and enhanced clinical benefit.

CONCLUSIONS

This simple and reliable clinical prediction nomogram model can help physicians evaluate children with NEC in a fast and effective manner, enabling the early identification and diagnosis of children at risk for surgery. It offers clinical revolutionary value for the development of medical or surgical treatment plans for children with NEC.

Initial surgical treatment of necrotizing enterocolitis: a meta-analysis of peritoneal drainage versus laparotomy

Necrotizing enterocolitis (NEC) in premature infants is associated with high morbidity and mortality, and the optimal intervention remains uncertain. To compare the mortality of primary peritoneal drainage versus primary peritoneal laparotomy as initial surgical intervention for NEC. All data were extracted from PubMed, Embase, and the Cochrane Library. Studies published up to December 2021. Patients with NEC. Studies centered on primary peritoneal drainage and primary peritoneal laparotomy as the initial surgical treatment. Mortality outcomes were available for both interventions. Randomized controlled trials, retrospective cohort studies, and case series in peer-reviewed journals. Language limited to English. Odds ratio (OR) with 95% confidence intervals (CIs) was used to evaluate mortality outcome. Subgroup analyses and linear regression were performed to ascertain the association between mortality pre-specified factors. Data of 1062 patients received peritoneal drainage and 2185 patients received peritoneal laparotomy from five case series, five retrospective cohort studies, and three randomized controlled trials. Peritoneal drainage caused similar mortality (OR 1.49, 95% CI 0.99-2.26) compared with peritoneal laparotomy as initial surgical management for NEC infants. The subgroup analysis of study design, sample size, birth weight, and sex showed similar findings, but inconsistent results were found for country (USA: 1.47, 95% CI 0.90-2.41; Canada: 2.53, 95% CI 0.30-21.48; Australia: 10.29, 95% CI 1.03-102.75; Turkey: 0.09, 95% CI 0.01-0.63) and gestational age (age mean difference < 3: 1.23, 95% CI 0.72-2.11; age mean difference ≥ 3: 2.29, 95% CI 1.04-5.05). No statistically significance was found for the linear regression between mortality and sample size (P = 0.842), gestational age (P = 0.287), birth weight (P = 0.257), sex (P = 0.6). Small sample size, high heterogeneity, NEC, and spontaneous intestinal perforation (SIP) had to be analyzed together, lack of selection criteria for the future selection of an intervention, and no clear, standardized procedures.   Conclusion: There was no significant difference in mortality between peritoneal drainage and laparotomy as initial surgical intervention. The results suggest that either intervention could be used in selected patients. What is Known: • Necrotizing enterocolitis (NEC) in premature infants is associated with high morbidity and mortality, and the optimal intervention remains uncertain. What is New: • No significant difference of mortality between peritoneal drainage and laparotomy as initial surgical intervention.

[Clinical guidelines for the diagnosis and treatment of neonatal necrotizing enterocolitis (2020)]

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease of neonates, especially of preterm infants, with high morbidity and mortality. The surviving infants may have digestive tract and neurological sequelae. Therefore, the prevention and treatment of NEC are of great significance in improving survival rate and survival quality of neonates. To provide evidence-based recommendations for management of NEC, the guidelines were developed based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) and the current domestic and overseas studies.