The Effects of Different Types of Steroids on Clinical Outcomes in Neonates with Meconium Aspiration Syndrome: A Systematic Review, Meta-Analysis and GRADE Assessment

Background and Objectives: Meconium aspiration syndrome (MAS) is a condition caused by the aspiration of meconium-stainted amniotic fluid into the lungs, resulting in pulmonary inflammation, neonatal morbidity, and mortality. It is important that these MAS infants receive appropriate care to avoid further complications. Steroids have an anti-inflammatory effect and may be effective in the management of MAS. The objective of the this study was to evaluate the effect of different steroids on clinical outcomes in infants with MAS. Materials and Methods: We systematically searched of PubMed/Medline, Scopus, Embase, Clinical Trials.gov, and Cochrane Library databases from inception to 24 January 2021 without language restriction. Only randomized controlled trials (RCTs) evaluating the effects of steroids in neonates with MAS were included. We calculated relative risks and weighted mean differences (MDs) with 95% confidence intervals (CIs) using a random-effects model to determine the associations between MAS and steroids and GRADE approach was employed for quality of evidence. The main outcomes measures were duration of respiratory distress, oxygen requirement, hospitalization, need for mechanical ventilation, death, and adverse drug reactions. Results: Seven RCTs involving 397 patients were analyzed. Nebulized budesonide and intravenous (IV) methylprednisolone shortened the duration of respiratory distress (MD, −2.46 days; 95% CI, −3.09 to −1.83 and MD, −3.30 days; 95% CI, −4.07 to −2.52, respectively) (moderate certainty). There was a reduction in duration of oxygen requirement in nebulized budesonide use (MD, −2.40 days; 95% CI, −3.40 to −1.40) (low certainty) and IV methylprednisolone use (MD, −3.30 days; 95% CI, −4.07 to −2.52) (moderate certainty). Nebulized budesonide shortened hospitalization stay (MD, −4.47 days; 95% CI, −8.64 to −0.30 days) (low certainty) as IV methylprednisolone use (MD, −7.23 days; 95% CI, −8.19 to −6.07 days) (moderate certainty). None of steroids benefits in death (low certainty). Conclusions: Certain types of steroids may benefit the respiratory aspect, but there was no decrease in mortality in MAS infants.


Introduction
Meconium aspiration syndrome (MAS) is caused by aspiration of meconium-containing amniotic fluid into the lungs. The complex chemical composition of meconium may be responsible for pulmonary inflammation, termed chemical pneumonitis, and a risk of surfactant inactivation [1]. The aspirated meconium may also cause mechanical obstruction of small airways. In neonates with partial airway occlusion, the over-expanded lungs will increase air leakage complications [2]. Around 5% to 20% of meconium-stained amniotic fluid (MSAF) infants develop MAS [3,4], with mortality rate of 5% [5,6]. The incidence of

Search Strategy and Selection Criteria
We performed a comprehensive and systematic search of the PubMed/Medline (U.S. National Library of Medicine, Bethesda, MD, USA), Scopus, Embase, Clinical Trials.gov, and Cochrane Library databases from inception to 24 January 2021 using keywords, synonyms, and other terms related to MAS and steroids without language restriction. Only randomized controlled trials (RCTs) were included. Additional studies were identified via the reference lists of selected articles.
Two reviewers (N.P. and W.T.) separately and independently screened and selected studies using the eligibility criteria. Any disagreements were resolved by discussion with a third reviewer (T.U.).

Data Extraction and Risk-of-Bias (Quality) Assessment
Two reviewers (N.P. and W.T.) separately extracted data from the included studies, including the study design and methodology, eligibility and diagnostic criteria, patient demographics, data collection method, definition of outcomes and outcomes parameters, and number of events. Study investigators were contacted for any missing data, unreported data, and additional details.
Two reviewers (N.P. and W.T.) independently evaluated the quality of the included studies using the Revised Cochrane risk-of-bias tool for randomized trials (RoB 2) [16]. Any disagreements were resolved by discussion with a third reviewer (T.U.).

Data Analyses
We calculated relative risks (RRs) and weighted mean differences (MDs) with 95% confidence intervals (CIs) using the DerSimonian and Laird method with a random-effects model to determine the associations between MAS and steroids in neonates with MAS for dichotomous and continuous outcomes, respectively [17]. We performed a separate analysis based on the type of steroids and assessed statistical heterogeneity via Q-statistic and I 2 tests. p-values of ≤0.05 indicated heterogeneity between studies [18]. I 2 values of 25%, 50%, and 75% denoted low, moderate, and high heterogeneity across studies, respectively [19]. If ≥10 studies proved eligible in each outcome, publication bias was evaluated using a funnel plot [20]. All statistical analyses were performed using Stata version 16.0 (StataCorp LLC, College Station, TX, USA).

Quality of Evidence
We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to rate the quality of evidence for each outcome as high, moderate, low, or very low [21]. The assessment included judgments addressing the risk of bias [22], imprecision [23], inconsistency [24], indirectness [25], and publication bias [26]. If there were serious concerns in any of these domains, we rated down the quality of evidence.
arate analysis based on the type of steroids and assessed statistical heterogeneity via Qstatistic and I² tests. p-values of ≤0.05 indicated heterogeneity between studies [18]. I² values of 25%, 50%, and 75% denoted low, moderate, and high heterogeneity across studies, respectively [19]. If ≥10 studies proved eligible in each outcome, publication bias was evaluated using a funnel plot [20]. All statistical analyses were performed using Stata version 16.0 (StataCorp LLC, College Station, TX, USA).

Quality of Evidence
We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to rate the quality of evidence for each outcome as high, moderate, low, or very low [21]. The assessment included judgments addressing the risk of bias [22], imprecision [23], inconsistency [24], indirectness [25], and publication bias [26]. If there were serious concerns in any of these domains, we rated down the quality of evidence.

Data Extraction and Risk-of-Bias Assessment Study Characteristics
The study characteristics and the maternal and infant characteristics are shown in Table 1, and Supplementary Table S1, respectively. Among the 10 studies, 1 compared lactose hydrous (placebo) and intravenous (IV) hydrocortisone [28]. Three studies compared IV normal saline solution (NSS) or no treatment versus IV dexamethasone [29,35,36]. Two studies compared nebulized NSS, IV 5% dextrose, or no treatment (control) versus IV methylprednisolone or nebulized budesonide [30,31]. Two studies compared nebulized NSS versus nebulized budesonide [32,33]. One study assigned patients to receive either nebulized 3% sodium chloride with IV NSS (placebo) or nebulized budesonide with IV methylprednisolone [37]. One study [34], patients received intratracheal instillation of porcine lung surfactant (PS) or intratracheal instillation of PS with budesonide. Definitions used in the included studies were as follows: 1.

2.
Sepsis [30] • Presence of clinical signs: poor feeding, weight loss, lethargy, temperature instability, sclerema, and capillary refill time of >3 s and; • Positive blood culture, or; • Two or more of the following laboratory abnormalities: (a) Total leukocyte count of <5000/mm 3 or >30,000/mm 3 ; (b) Immature/total neutrophil ratio of >0.2; (c) Micro-erythrocyte sedimentation rate of >5 mm in the first hour on the first day of life or >15 mm at any time; (d) Positive C-reactive protein.

Data Analyses
The efficacy of steroids on clinical outcomes, ADRs, and complications in infants with MAS are shown in Figures 2 and 3, Table 2, and Supplementary Tables S3, S4 and Figure S1.

Duration of Mechanical Ventilation
Three RCTs [29,32,37] determined the effect of steroids on the duration of mechanical ventilation. Two RCTs [29,37] calculated the MD, which one RCT showed no difference in the duration of mechanical ventilation between dexamethasone and placebo (MD, −1.10 days; 95% CI, −2.79 to 0.59 days) [29]. Duration of hospitalization 6.

Downes' Score
Two RCTs reported Downes' score [33,37]. One study [33] reported a lower mean Downes' score (over 5 days) in the nebulized budesonide group than in the control group (p < 0.05). The other study [37] showed a lower median Downes' score (days 2-7) in the nebulized budesonide with IV methylprednisolone group than in the control group (p < 0.05).

Duration of X-ray Clearance
Three RCTs [28,30,31] provided evidence regarding the duration of X-ray clearance. Two RCTs [30,31] determined this effect of nebulized budesonide and IV methylprednisolone with very low-quality evidence (MD, −5.99 days; 95% CI, −12.53 to 0.56 days and MD, −5.83 days; 95% CI, −12.51 to 0.85 days, respectively) ( Figure 2D, Table 2, and  Supplementary Tables S3 and S4).       The effect of dexamethasone on the need for mechanical ventilation is very uncertain.

Duration of hospitalization, NICU stay, and PICU stay (days)
Budesonide 208 (4 studies) -  Abbreviations: CI = confidence interval; RCTs = randomized controlled trials; MAS = meconium aspiration syndrome; MD = mean difference; NICU = neonatal intensive care unit; PICU = pediatric intensive care unit. Footnote: 1 Using the median baseline risk in the control group of eligible RCTs. GRADE Working Group grades of evidence. High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty ⊕⊕⊕ : We are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty ⊕⊕ : Our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty ⊕ : We have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of the effect.

Time until Achievement of Full Feeding
Three RCTs [30][31][32] provided evidence regarding nebulized budesonide on time taken to full feeding in neonates with MAS. Two RCTs [30,32] showed a significantly shorter time until full feeding in the nebulized budesonide group than in the placebo or no treatment group with very low-quality evidence (MD, −6.54 days; 95% CI, −8.94 to −4.13 days) ( Figure 2F and Supplementary Tables S3 and S4).

Infections and Complications
We performed meta-analyses of infections and other complications, including pneumothorax, hypotension, hypoglycemia, hyperbilirubinemia, and seizure ( Figure 3, Table 2, and Supplementary Tables S3, S4 and Figure S1). There was no significant association of steroids with infections and complications with low-to very low-quality evidence. A metaanalysis could not be performed for hypocalcemia, respiratory arrest, PPHN including the need for pulmonary vasodilators, anemia, stage 2 hypoxic-ischemic encephalopathy, and diarrhea (Supplementary Table S4 and Figure S1). One study [30] revealed no cases of hypertension or hyperglycemia in both the nebulized budesonide and IV methylprednisolone groups. One patient each in the nebulized budesonide and placebo groups developed hyperglycemia in one study [32].

Discussion
We included all available RCTs to evaluate the effectiveness, safety, and adverse effects of different types of steroids in infants with MAS. Our results show the benefits of both nebulized budesonide and IV methylprednisolone on the duration of respiratory distress, oxygen requirement, and hospitalization, including ICU admission (moderateto low-quality evidence). Nebulized budesonide shortens the time until achievement of full feeding (very low-quality evidence) without statistically significant increases in the incidence of infections and complications (low-to very low-quality evidence). There was no reduction of mortality regardless of the type of steroid administration.
We performed a rigorous and systematic search to identify relevant studies using the revised version of the Cochrane risk-of-bias tool. We assessed the certainty of evidence for each outcome using the GRADE approach [16,21] our protocol was registered in PROSPERO, and reporting the results followed the PRISMA statement.
Based on the pathophysiology of MAS, treatments to reduce inflammation and cytokine production should benefit patients with MAS. The instillation of budesonide with surfactant has been shown to improve the respiratory status in animal studies [38]. Man-agement of MAS in infants mainly involves supportive respiratory and cardiovascular care, with other modalities such as surfactants [39]. Insufficient treatment data in previous studies (e.g., steroids) were investigated in our study.
The effect of steroids on MAS in infants was evaluated in a Cochrane meta-analysis [15]; however, it included only studies by Yeh et al. [28] and Wu et al. [29] This meta-analysis showed no effect of steroids on the duration of oxygen therapy or mortality rate because of insufficient evidence.
Our study updated the current data regarding the effects of steroids on MAS with more relevant clinical outcomes and complications. In addition, other outcomes, such as pulmonary hypertension and respiratory arrest, were additionally identified and are shown in Supplementary Figure S1.
There was no significant difference in the occurrence of PPHN among neonates with MAS with/without steroids [30,33,34,36]. Pneumothorax also showed no difference in neonates with/without budesonide [32,33]. No significant increase in either hypertension or hyperglycemia among neonates with steroids was reported [30,32].

Strengths and Limitations
Our comprehensive and systematic search with separate and independent screening, searching, study selection, data extraction, quality assessment of this review focused on important outcomes. The GRADE approach was used to rate the quality of evidence, including risk of bias, inconsistency, indirectness, imprecision, and publication bias.
There are several limitations. Even though only RCTs were evaluated, the quality varied from moderate to very low. For outcomes, the quality rating of evidence was decreased by one level based on the risk of bias (Table 2 and Supplementary Table S3). Adequate allocation sequence and concealment were reported in five studies [28,[30][31][32][33] and one study [30], respectively. A blinding process was performed in three studies (Supplementary Table S2) [28,29,31]. For some outcomes, we decreased the quality of evidence rating by one level based on high heterogeneity (I 2 > 50%) ( Table 2 and Supplementary Table S3).
Notably, most of the included studies were performed in Asian populations, and 7 of the 10 studies were conducted in India or countries with low resource settings.
Patients were not severe as not much initial requirement of mechanical ventilation in most studies, and data on severity of pulmonary disease, such as oxygen index, were not provided. The analysis is also limited by the different methodology performed in each study and the relatively small number of infants available to assess each outcome. There is variability between the reported studies. Otherwise, the long-term outcomes of steroids, such as neurodevelopmental results, should be followed. Thus, the largesample, uniform methodology and high-quality RCTs involving different populations should further confirm the effect of steroids in infants with MAS.

Conclusions
For infants with MAS, certain types of steroids may be beneficial in reducing the duration of respiratory distress, oxygen requirement, hospital stay, and time until achievement of full feeding without short-term complications. However, no benefits of decreased mortality in any types of steroid use.
Supplementary Materials: The following are available online at https://www.mdpi.com/article/10 .3390/medicina57111281/s1. Supplement Table S1: baseline maternal and neonatal characteristics of the included studies; Supplement Table S2: risk-of-bias summary of the included studies using revised Cochrane risk-of-bias tool for randomized trials; Supplement Table S3: GRADE evidence profile of the evidence outcomes; Supplement Table S4: summary results of the included studies categorized by outcomes; Supplement Figure S1: results of the outcomes in the systematic review and meta-analysis.
Author Contributions: All authors had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: N.P. and W.T.; acquisition, analysis, and interpretation of data: N.P. and W.T.; drafting of the manuscript: N.P., T.U., and W.T.; critical revision of the manuscript for important intellectual content: N.P., T.U. and W.T.; statistical analysis: W.T.; administrative, technical, or material support: Not applicable. All authors have read and agreed to the published version of the manuscript.