Probiotics for the prevention of Hirschsprung‐associated enterocolitis

Abstract

Background

Hirschsprung‐associated enterocolitis (HAEC) is a leading cause of serious morbidity and potential mortality in children with Hirschsprung's disease (HD). People with HAEC suffer from intestinal inflammation, and present with diarrhoea, explosive stools, and abdominal distension. Probiotics are live microorganisms with beneficial health effects, which can optimise gastrointestinal function and gut flora. However, the efficacy and safety of probiotic supplementation in the prevention of HAEC remains unclear.

Objectives

To assess the effects of probiotic supplements used either alone or in combination with pharmacological interventions on the prevention of Hirschsprung‐associated enterocolitis.

Search methods

We searched CENTRAL, PubMed, Embase, the China BioMedical Literature database (CBM), the World Health Organization International Clinical Trials Registry, ClinicalTrials.gov, the Chinese Clinical Trials Registry, Australian New Zealand Clinical Trials Registry, and Clinical Trials Registry‐India, from database inception to 27 February 2022. We also searched the reference lists of relevant articles and reviews for any additional trails.

Selection criteria

Randomised controlled trials (RCTs) comparing probiotics and placebo, or any other non‐probiotic intervention, for the prevention of HAEC were eligible for inclusion.

Data collection and analysis

Two review authors independently extracted data and assessed the risk of bias of the included studies; disagreements were resolved by discussion with a third review author. We assessed the certainty of evidence using the GRADE approach. We calculated odds ratios (ORs) with 95% confidence intervals (CIs) for dichotomous outcomes.

Main results

We included two RCTs, with a total of 122 participants. We judged the overall risk of bias as high. We downgraded the evidence due to risk of bias (random sequence generation, allocation concealment, and blinding) and small sample size.

The evidence is very uncertain about the effect of probiotics on the occurrence of HAEC (OR 0.58, 95% CI 0.10 to 3.43; I² = 74%; 2 studies, 120 participants; very low‐certainty evidence). We found one included study that did not measure serious adverse events and one included study that reported no serious adverse events related to probiotics. Probiotics may result in little to no difference between probiotics and placebo in relation to the severity of children with HAEC at Grade I (OR 0.66, 95% CI 0.14 to 3.16; I² = 25%; 2 studies, 120 participants; low‐certainty evidence). The effects of probiotics on the severity of HAEC at Grade II are very uncertain (OR 1.14, 95% CI 0.01 to 136.58; I² = 86%; 2 studies, 120 participants; very low‐certainty evidence). Similarly, the evidence suggests that probiotics results in little to no difference in relation to the severity of HAEC at Grade III (OR 0.43, 95% CI 0.05 to 3.45; I² = 0%; 2 studies, 120 participants; low‐certainty evidence).

No overall mortality or withdrawals due to adverse events were reported. Probiotics may result in little to no difference in the recurrence of episodes of HAEC compared to placebo (OR 0.85, 95% CI 0.24 to 3.00; 1 study, 60 participants; low‐certainty evidence).

Authors' conclusions

There is currently not enough evidence to assess the efficacy or safety of probiotics for the prevention of Hirschsprung‐associated enterocolitis when compared with placebo. The presence of low‐ to very‐low certainty evidence suggests that further well‐designed and sufficiently powered RCTs are needed to clarify the true efficacy of probiotics.

Plain language summary

The use of probiotics to prevent Hirschsprung‐associated enterocolitis

Review question

What are the benefits and risks of using probiotics to prevent Hirschsprung‐associated enterocolitis (HAEC)?

Key messages

We compared randomised controlled trials (RCTS) of probiotics versus placebo, or any other non‐probiotic intervention, to prevent Hirschsprung‐associated enterocolitis (HAEC). There is currently not enough evidence to assess the efficacy or safety of probiotics for the prevention of HAEC.

What is HAEC?

HAEC is a rare condition. It can cause inflammation of the bowels and lead to symptoms, such as abdominal pain and diarrhoea, which can disturb the balance of electrolytes in the body.

What are probiotics?

Probiotics are live bacteria that may restore the natural balance of bacteria, and possibly reduce inflammation of the gut. However, it is not yet clear whether taking probiotics is helpful in preventing HAEC, and if they are safe. We analysed the scientific evidence to answer this question.

What did we want to find out？

We wanted to find out if probiotics could prevent HAEC, and if probiotics were associated with any unwanted effects.

What did we do?

We searched for studies that examined probiotics compared with placebo or any other intervention in children with Hirschsprung's disease (HD). We compared and summarised the results of the studies, and rated our confidence in the evidence.

What did we find?

We included two RCTs, with a total of 122 people with HAEC. One multicentre trial was conducted in the USA and Egypt, and one in China. Each of these studies was carried out in a hospital setting. A total of 60 participants were treated with probiotics, and 60 were treated with a placebo (a fake medication). Time of enrolment ranged from 1 to 12 months. One study was funded by companies that supplied the probiotics; the other by government agencies. Taken together, the results suggest that there is not enough evidence to show that probiotics can prevent HAEC.

Main results

We are very uncertain whether there was a difference in the occurrence of HAEC between the group receiving probiotics and the group receiving placebo. No serious adverse events were reported. We are very uncertain about the effect of probiotics on the severity of HAEC.

No overall mortality or withdrawals due to adverse events were reported. There was little or no difference in the recurrence of HAEC between the two groups. Since the studies were very small, and poorly reported, we are unable to draw any definite conclusions at this time. Better‐designed studies with more participants are needed.

What were the limitations of the evidence?

The certainty of the evidence varied from low to very low, mainly because the results were inconclusive, and there were not enough available date.

How up to date is this evidence?

The evidence is up to date to 27 February 2022.

Summary of findings

Summary of findings 1. Probiotics compared to placebo for the prevention of Hirschsprung‐associated enterocolitis.

Probiotics compared to placebo for the prevention of Hirschsprung‐associated enterocolitis
Patient or population: children with Hirschsprung's disease (HD) Setting: hospital Intervention: probiotics Comparison: placebo
Outcomes		Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	No. of participants (studies)	Certainty of the evidence (GRADE)	Comments
		Risk with placebo	Risk with probiotics
Occurrence of HAEC		Study population		OR 0.58 (0.10 to 3.43)	120 (2 RCTs)	⊕⊝⊝⊝ Very lowa
		293 per 1000	194 per 1000 (40 to 587)
Serious adverse events		See comment	See comment	Not estimable	60 (1 RCT)	See comment	0 participants developed serious adverse events in this study
Severity of HAEC	Grade I	Study population		OR 0.66 (0.14 to 3.16)	120 (2 RCTs)	⊕⊕⊝⊝ Lowb
		121 per 1000	83 per 1000 (19 to 303)
	Grade II	Study population		OR 1.14 (0.01 to 136.58)	120 (2 RCTs)	⊕⊝⊝⊝ Very lowc
		121 per 1000	135 per 1000 (1 to 949)
	Grade III	Study population		OR 0.43 (0.05 to 3.45)	120 (2 RCTs)	⊕⊕⊝⊝ Lowd
		52 per 1000	23 per 1000 (3 to 158)
Overall mortality		See comment	See comment	Not estimable	60 (1 RCT)	See comment	0 participants died from the intervention in this study
Withdrawals due to adverse events		See comment	See comment	Not estimable	60 (1 RCT)	See comment	0 participants withdraw due to adverse events in this study
Recurrent episodes of HAEC		Study population		OR 0.85 (0.24 to 3.00)	60 (1 RCT)	⊕⊕⊝⊝ Lowe
		200 per 1000	187 per 1000 (61 to 449)
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; HAEC: Hirschsprung‐associated enterocolitis; OR: odds ratio; RCT: randomised controlled trial
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 effect

^aDowngraded three times: overall unclear risk of bias, imprecision due to small sample size, and inconsistency due to significant heterogeneity among studies (I² = 74%).
^bDowngraded two times: overall unclear risk of bias, and small number of events.
^cDowngraded three times: overall unclear risk of bias, imprecision due to small sample sizes, and inconsistency due to serious inconsistency (I² = 86%).
^dDowngraded two times: overall unclear risk of bias, and imprecision due to small number of studies for this outcome.
^eDowngraded two times: overall unclear risk of bias, and imprecision due to small sample size in a single study.

Background

Description of the condition

Hirschsprung's disease (HD) is a congenital malformation, characterised by continuous spasms of the intestinal tract, due to a lack of ganglion cells in the colon and faecal stasis in the proximal colon, which lead to hypertrophy and expansion of the proximal colon (Yan 2019). The incidence of HD varies from one in 5000 to one in 10,000 live births, and it appears to be more common in males than females, with a ratio of 3:1 to 5:1, especially in short‐segment disease (Liu P 2010). HD has traditionally been classified as short segment and long segment, which refer to the extent of the paucity of enteric neurons in the gut region, called an 'aganglionic zone' (Tam 2009). Short‐segment disease is most common, and is confined to the rectosigmoid region. Long‐segment disease extends into this area, and affects the entire colon. The small intestines are rarely involved (Stewart 2003).

The main treatment for HD is radical surgery. Many approaches are used, including the transabdominal approach and the transanal endorectal pull‐through. The most common transabdominal operations for HD are the Swenson, Rehbein, Duhamel, and Soave procedures (Chen 2013). Although surgery improves the overall prognosis of HD, postoperative complications occur in varying degrees, among which Hirschsprung‐associated enterocolitis (HAEC) is the most serious (Gosain 2015). People with HAEC suffer from intestinal inflammation, and present with diarrhoea, explosive stools, and abdominal distension (Pastor 2009). HAEC can occur at any time during the course of the disease. The incidence of HAEC is around 6% to 26% at the time of HD diagnosis, and increases to between 5% and 42% during the postoperative course following the pull‐through procedure (Farokh 2013). The reported incidence of HAEC varies markedly between different types of HD and the time of diagnosis. HAEC occurs more frequently in the long‐segment type than the short‐segment type (Jiao 2016). However, the aetiology of this severe, life‐threatening complication remains poorly understood. Important factors related to intestinal inflammation include the mucous barrier, intestinal microbiota, and immune function (Jiao 2016). Appropriate function of the intestinal mucosal barrier is thought to play an important role in the prevention of HAEC. Abnormal composition of intestinal mucosal proteins will lead to the dysfunction of mucus barrier, which then contributes to HAEC (Mattar 2003).

The lack of a standardised clinical definition of HAEC has been addressed many times. In 2009, using the Delphi method to achieve consensus among a panel of experts for a HAEC clinical and radiographic diagnosis, Pastor and colleagues explained that a total score was calculated based on clinical predictors, such as radiographic diagnosis and physical examination, with a cut‐off score of 10 being indicative of a diagnosis of HAEC (Pastor 2009). However, Frykman and colleagues critically evaluated these criteria, and suggested that this HAEC cut‐off score was too restrictive. They suggested that it might fail to identify milder episodes, and better sensitivity would be achieved with a cut‐off of 4 (Frykman 2018). While a significant step forward in better defining the most important criteria, the preliminary score was cumbersome for routine clinical use, and was limited to case scenario applications. More recently, the American Pediatric Surgical Association Board of Governors categorised the clinical uncertainty and severity of HAEC into three grades, based on history, physical examination, and imaging studies, which have been universally adopted in clinical settings (Gosain 2017).

Description of the intervention

Probiotics are live microorganisms, which in adequate amounts, are believed to offer health benefits to the human body (Wallace 2011). The most commonly used probiotics are Lactobacillus casei, Bifidobacterium infantis, and Saccharomyces boulardii (Islam 2016). Data are available to illustrate the benefits of probiotics in preventing and treating different conditions; the gastrointestinal tract is a common target of probiotics (Williams 2010). A review of 420 randomised studies, published between 1977 and 2014, reported that some of the most common indications for probiotics were antibiotic‐associated diarrhoea, Helicobacter pylori infection, and acute paediatric diarrhoea (McFarland 2015). There are plenty of theories for the potential mechanisms behind the beneficial effects of probiotics, such as optimised gastrointestinal function, and gut flora (Blandino 2008; Lindsay 2014). However, despite the wide variety of disease states in the critically ill in which positive effects of probiotics have been noted, for both prevention and treatment, many uncertainties remain about the overall safety, dosing, and administration of probiotics (Lindsay 2014; Sanders 2010).

How the intervention might work

Enterally administered probiotics act through diverse mechanisms, affecting factors associated with the occurrence of HAEC, including dysbiosis of the intestinal microbiome, impaired mucosal barrier function, altered innate immune responses, and bacterial translocation. The potential mechanisms of action are:

• Regulate intestinal flora balance: as pharmacological effects, probiotics can directly supply the body’s normal physiological bacteria, adjust the intestinal flora balance, inhibit and eliminate intestinal pathogens, reduce intestinal toxins, promote the body's digesting of nutrients, synthesise vitamins that are required by the organism, and stimulate immunity (Kang 2015; Khan 2012).

• Enhance epithelial barrier function: lactobacilli and bifidobacteria are markedly reduced in people with HAEC, which may result in decreased epithelial barrier function. Treatment with probiotics may help prevent HAEC by enhancing epithelial barrier function (Goulet 2015).

• Maintain intestinal mucosal integrity: potentially, probiotics play a protective role in maintaining intestinal mucosal integrity through a number of different interactions, including alterations in mucosal cytokine expression, and competing with intestinal pathogens for mucosal receptors, thereby, increasing transepithelial resistance (Isabel 2012).

• Reduce bacterial translocation: HAEC is often accompanied by abnormal mucin production and secretion, resulting in impaired mucus barrier function and intestinal bacterial translocation; probiotics can promote mucin secretion, increase epithelial expression of mucin, and reduce bacterial translocation (Murphy 2005; Wang 2015).

Why it is important to do this review

Many studies have demonstrated the potential beneficial effects of probiotics in decreasing the risk of inflammatory diseases of the intestine, such as necrotizing enterocolitis (Sharif 2020). However, there is still uncertainty about the effects of probiotics on HAEC. A marked decrease in Lactobacillus species and Bifidobacteria species in children with HAEC has been reported (Shen 2009). The use of prophylactic oral probiotics in people suffering from HD has been shown to reduce the morbidity of HAEC, and also to reduce the severity of the condition (Wang 2015); however, other research has found the morbidity associated with HAEC to be similar between probiotics and placebo (El‐Sawaf 2013). Currently, the efficacy and safety of probiotic supplementation for preventing HAEC is unclear. The results from this review will confirm whether existing data support the use of probiotics in people with HD.

Objectives

To assess the effects of probiotic supplements, used either alone or in combination with pharmacological interventions, on the prevention of Hirschsprung‐associated enterocolitis.

Methods

Criteria for considering studies for this review

Types of studies

We included randomised controlled trials (RCTs), with no restrictions on language or publication status.

Types of participants

We included participants 18 years of age or younger, with a confirmed diagnosis of Hirschsprung's disease (HD). Diagnosis of HD was to be confirmed by physical examination, contrast enema, anorectal manometry, or rectal suction biopsy (Martucciello 2005; Mei 2020).

We excluded children with significant birth defects, and those who had taken oral antibiotics, commercial probiotic yogurt products, or other gastrointestinal motility agents that could affect the gut flora within a week. We also excluded children who were haemodynamically unstable, or had active septicaemia.

Types of interventions

Any probiotic versus placebo, or any probiotic combined with another drug versus the other drug alone. There were no limitations in species and dosage of the probiotic.

We believed it was inappropriate to compare probiotics with another type of drug alone, therefore, we excluded such studies.

Types of outcome measures

Primary outcomes

1. Occurrence of Hirschsprung‐associated enterocolitis (HAEC)

2. Serious adverse events

3. Severity of HAEC: the guidelines for the diagnosis of HAEC classifies severity as grade I (possible HAEC), grade II (mild or moderate HAEC), and grade III (severe HAEC), based on clinical history, physical examination, and radiographic findings (Gosain 2017; Appendix 1).

Secondary outcomes

1. Overall mortality (all‐cause mortality during the initial hospital stay that occurred from the time of randomisation)

2. Withdrawals due to adverse events

3. Recurrent episodes of HAEC

Search methods for identification of studies

Electronic searches

We searched the following databases for relevant studies (Appendix 1).

1. The Cochrane Central Register of Controlled Trials (CENTRAL; 2022, Issue 2) in the Cochrane Library (searched 27 February 2022)

2. PubMed (1946 to 27 February 2022)

3. Embase Ovid (1984 to 2022 Week 9)

4. China BioMedical Literature database (CBM; 1978 to 27 February 2022)

We searched the following trial registers for eligible ongoing and unpublished studies, using the following search terms: “Hirschsprung enterocolitis, Hirschsprung's enterocolitis, Hirschsprung's associated enterocolitis, Hirschsprung associated enterocolitis and probiotics”.

1. World Health Organization International Clinical Trials Registry Platform (apps.who.int/trialsearch; searched 27 February 2022)

2. US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.clinicaltrials.gov; searched 27 February 2022)

3. Chinese Clinical Trials Registry (www.chictr.org.cn; searched 27 February 2022)

4. Australian New Zealand Clinical Trials Registry (www.anzctr.org.au; searched 27 February 2022)

5. Clinical Trials Registry ‐ India (CTRI; www.ctri.nic.in/Clinicaltrials; searched 27 February 2022)

Searching other resources

We checked the bibliographies of included studies and screened the reference lists of relevant review articles to identify additional potentially relevant studies for inclusion. We used free‐text terms to access studies not yet indexed and database‐specific subject headings. We also contacted trial authors to request incomplete information on unpublished or ongoing studies, or to request additional trial data.

Data collection and analysis

Selection of studies

Two review authors (FM, FC) independently screened titles and abstracts to identify potentially eligible studies, based on the inclusion criteria, and retrieved the full‐text articles for further assessment. Disagreements between the review authors at either stage were tracked and resolved by discussion, with arbitration by a third author (BM) if consensus was not achieved.

Data extraction and management

Two review authors (QG, LZ) independently extracted relevant study data from the eligible studies and recorded them on a pre‐tested data extraction form. We resolved discrepancies by discussion, or by consulting a third review author (BM). We contacted the corresponding authors of included trials to seek additional information or missing information, if required.

We extracted the following information from included studies.

1. Trial design and methodological characteristics: study design, study location, study setting, information to inform the risk of bias assessment

2. Characteristics of study participants: sample size, mean age, gender, diagnosis criteria, inclusion criteria, exclusion criteria, withdrawals, and other relevant characteristics

3. Information on the types of interventions used in studies: intervention, comparison, type, dose, and duration of probiotic(s)

4. Outcomes: primary and secondary outcomes specified and collected, time points reported, including the occurrence of HAEC, HAEC severity, overall mortality, number of recurrent episodes of HAEC, and adverse events

Assessment of risk of bias in included studies

Two review authors (WM, YW) independently assessed each study for risk of bias using RoB 1 and instructions in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2017).

We judged each study as being at low, high, or unclear risk of bias for each of the following domains.

1. Random sequence generation (selection bias)

2. Allocation concealment (selection bias)

3. Blinding of participants and personnel (performance bias)

4. Blinding of outcome assessment (detection bias)

5. Completeness of outcome data (attrition bias)

6. Selective reporting (reporting bias)

7. Other sources of bias

Measures of treatment effect

We expressed the treatment effects of dichotomous outcomes as odds ratios (ORs), with corresponding 95% confidence intervals (CIs (Higgins 2020)). For time‐to‐event outcomes, we calculated the hazard ratio (HR) and corresponding 95% CI, when possible.

Unit of analysis issues

We did not anticipate cross‐over trials or cluster‐RCTs in this Cochrane Review. In the case of trials with multiple arms, we included only the arms that met the eligibility criteria. If we incorporated more than one eligible intervention arm from a study, we combined all relevant intervention groups to create a single pairwise comparison in order to avoid the problem of including the same group of participants twice in the same meta‐analysis.

Dealing with missing data

We contacted the authors of the included trials regarding any missing trial data. For dichotomous data that remained missing or unclear, we used an intention‐to‐treat analysis (i.e. participants who were lost to follow‐up or had missing outcome data were counted as having an absence of the outcome).

For continuous outcomes, we estimated the individual missing statistics, such as standard deviations (SDs), using relevant statistical tools with available data from the trial (e.g. P values, CIs), according to methods described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2020). If it was not possible to calculate the SD from the P value or the CIs, we imputed the SD using the largest SD in other trials for that outcome.

We also planned to undertake a sensitivity analysis when we imputed SDs from other trials, in order to further examine the impact of this imputation. As no studies reported continuous outcomes, we did not follow these methods in our analysis.

Assessment of heterogeneity

To examine the heterogeneity among trials, we quantified heterogeneity using the Chi² test on N‐1 degrees of freedom, with a significance level of P < 0.05, as well as the I² statistic. We interpreted I² results as suggested in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2020).

1. 0% to 40% might not be important

2. 30% to 60% may represent moderate heterogeneity

3. 50% to 90% may represent substantial heterogeneity

4. 75% to 100% may represent considerable heterogeneity

If the I² statistic estimate was greater than 50%, we regarded the level of heterogeneity among trials as moderate, substantial or considerable. We explored possible causes by prespecified subgroup analyses (Subgroup analysis and investigation of heterogeneity). In the presence of 75% or more heterogeneity in meta‐analysis, we assessed whether it was appropriate to report the meta‐analysis in the review report.

Assessment of reporting biases

We had planned to inspect funnel plot asymmetry for evidence of publication bias if there were at least 10 studies available, however we were unable to undertake this, due to the small number of included studies.

Data synthesis

We analysed the data using Review Manager 5 (Review Manager 2020). We combined data in meta‐analysis when we determined, by consensus, that participant groups, interventions, and outcomes were sufficiently similar for pooling to be appropriate. Assuming some degree of heterogeneity across included trials, we combined the outcomes from the individual trials using a random‐effects model. When the heterogeneity was too high (such that meta‐analysis was inappropriate), or when we only identified one study, we conducted a narrative synthesis to summarise the evidence and characteristics of included studies.

Subgroup analysis and investigation of heterogeneity

We planned subgroup analyses based on the following.

1. Age group: children aged younger than one year; children aged one to three years; children older than three years of age

2. Gender: male and female

3. Country: studies conducted in high‐income countries and studies conducted in low‐ and middle‐income countries (as we expect the study setting to influence heterogeneity)

4. Different types of probiotics

5. Different types of HD: long‐segment aganglionosis and short‐segment aganglionosis

However, as insufficient data were available, we did not undertake any of these analyses.

Sensitivity analysis

We planned to conduct sensitivity analyses to determine the impact of excluding studies with high risk of bias, and studies for which we imputed data. However, we did not undertake these analyses due to the lack of studies.

Summary of findings and assessment of the certainty of the evidence

We created summary of findings tables using GRADEpro GDT online software, and reported each of the following outcomes.

1. Occurrence of HAEC

2. Serious adverse events

3. Severity of HAEC (Grade I, Grade II, Grade III)

4. Overall mortality

5. Withdrawals due to adverse events

6. Recurrent episodes of HAEC

Three review authors (FM, KH, JSWK) independently graded the certainty of the evidence for each outcome with a four‐level rating scale (i.e. high, moderate, low, or very low), using the GRADE classification (Guyatt 2008). Any disagreements were resolved by a fourth review author (BM).

We followed the recommendations described in the Cochrane Handbook for Systematic Reviews of Interventions, and downgraded the certainty of the body of evidence by considering: risk of bias or study limitations, unexplained heterogeneity or inconsistency of results, indirectness of the evidence, imprecision of results, and publication bias, based on these factors (Schünemann 2020). The GRADE approach interprets the four levels of certainty as follows.

1. High certainty: we are very confident that the true effect lies close to that of the estimate of the effect.

2. 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.

3. Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect.

4. 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 effect.

Results

Description of studies

Please see Characteristics of included studies and Characteristics of excluded studies.

Results of the search

The electronic searches, conducted on 27 February 2022, yielded a total of 14 relevant studies from electronic databases, and three from additional searches. After removing duplicates, we screened the remaining 15 records. We excluded 11 records because they did not match the inclusion criteria. After the full‐text screening, we excluded one more record (12 excluded records in total), and categorised one study as ongoing. We included two eligible studies in the final analysis. Our study selection process is illustrated in Figure 1.

1.

Study flow diagram

Included studies

We provide details of the included studies in Characteristics of included studies.

Study design and setting

Both included studies were parallel‐group, randomised controlled trials (RCTs); the unit of allocation was the individual participant. One of the included studies took place in the USA and Egypt (El‐Sawaf 2013), and the other in China (Wang 2015).

Participants

In El‐Sawaf 2013, two subjects receiving placebo were dropped from the final study analysis: one had early post‐pullthrough death from unrelated causes (pneumonia and sepsis, 1 week post‐pullthrough), and the other was completely noncompliant.

Two studies, with a total of 120 participants, were included in our meta‐analysis; 60 received various interventions, and 60 were in the control groups. Participants in Wang 2015 were under the age of 18 months; El‐Sawaf 2013 assessed children of 48 months or younger. One study stated that Hirschsprung's disease (HD) was diagnosed based on suction rectal biopsy results (El‐Sawaf 2013). The other study based the diagnosis on barium enema, anorectal manometry, and postoperative pathological examination (Wang 2015). Both studies reported the incidence of long‐segment aganglionosis.

Intervention

The studies examined the use of probiotics in different combinations and duration. Participants in El‐Sawaf 2013 were given VSL#3, a probiotic preparation containing 90 billion viable lyophilised bacteria (per packet), composed of Lactobacillus, Bifidobacterium, and Streptococcussalivarius subsp for three months. Wang 2015 used oral Bifidobacterium, Lactobacillus acidophilus, and Enterococcus triple viable capsules for four weeks.

Control comparisons

Both trials used maize starch for the comparison.

Outcomes

Both studies reported the occurrence and severity of Hirschsprung‐associated enterocolitis (HAEC) as their major outcomes. Neither study reported serious adverse events, overall mortality, or withdrawals due to adverse events. Only one study reported data on recurrent episodes of HAEC (El‐Sawaf 2013).

Funding and declaration of interest

The drugs used in one of the trials were supplied by pharmaceutical companies, with no declarations of interest (El‐Sawaf 2013).

Excluded studies

Overall, we excluded 12 studies (see the Characteristics of excluded studies). Nine studies were not RCTs (Demehri 2015; Frykman 2015; Li 2016; Liang 2013; Nakamura 2018; Qu 2010; Soh 2018; Yin 2011; Zheng 2011); three studies did not investigate HAEC (Xia 2010; Zhou 2008; Zhu 2014).

Ongoing studies

We identified one ongoing study (NCT02343562).

Risk of bias in included studies

Our judgements regarding the risk of bias in each of the included trials are in Characteristics of included studies. See Figure 2 and Figure 3 for summaries.

2.

Risk of bias graph: review authors' judgements about each risk of bias item, presented as percentages across all included studies

3.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study

Allocation

All included studies were at low risk of bias for random sequence generation. Wang 2015 reported that random sequence generation was performed by random number table row, and El‐Sawaf 2013 described using block randomisation.

Since Wang 2015 did not report their methods of allocation concealment, we assessed them at unclear risk of bias. Although El‐Sawaf 2013 used envelopes, other details of safeguards were not provided, so we assessed risk of bias for concealment of allocation as unclear.

Blinding

Both studies were specifically reported as placebo‐controlled randomised trials, and so we considered these studies to be at low risk of performance bias.

We judged both studies at unclear risk of detection bias, as they did not provide information about blinding of subjective outcome assessments.

Incomplete outcome data

El‐Sawaf 2013 reported that only two participants were lost to follow‐up from the control group; their data were excluded from the final analyses: one due to early post‐pullthrough death from unrelated causes, and one due to complete noncompliance. Wang 2015 reported no losses to follow‐up or withdrawals. We judged both studies at low risk of attrition bias.

Selective reporting

We judged the two studies at low risk of selective reporting bias because they adequately reported the prespecified outcomes reported in the trial registers.

Other potential sources of bias

We considered both studies to be at low risk of bias for other potential sources of bias. One included study reported power calculations, and reported that the study was supported by pharmaceutical companies, but specified there was no influence on the results (El‐Sawaf 2013). One study was funded by the National Key Specialty Construction Program and National Natural Science Foundation of China (Wang 2015).

Effects of interventions

See: Table 1

See: Table 1.

Probiotics compared to placebo for the prevention of Hirschsprung‐associated enterocolitis

Primary outcomes

Occurrence of HAEC

Both trials reported this outcome. The evidence is very uncertain about the effect of probiotics on the occurrence of HAEC compared with placebo (odds ratio (OR) 0.58, 95% confidence interval (CI) 0.10 to 3.43; I² = 74%; 2 studies, 120 participants; very low‐certainty evidence; Analysis 1.1).

1.1. Analysis.

Comparison 1: Probiotics versus placebo, Outcome 1: Occurence of Hirschsprung‐associated enterocolitis (HAEC)

Serious adverse events

El‐Sawaf 2013 reported no serious adverse events throughout the duration of the studies; Wang 2015 did not measure the outcome. 

Severity of HAEC

Both trials reported this outcome. Compared to placebo, probiotics may result in little to no difference in the severity of HAEC in children with possible HAEC (Grade I; OR 0.66, 95% CI 0.14 to 3.16; I² = 25%; 2 studies, 120 participants; low‐certainty evidence; Analysis 1.2), and severe HAEC (Grade III; OR 0.43, 95% CI 0.05 to 3.45; I² = 86%; 2 studies, 120 participants; low‐certainty evidence; Analysis 1.2). The clinical benefit of probiotics compared to placebo was very uncertain in the severity of children with mild or moderate HAEC (Grade II; OR 1.14, 95% CI 0.01 to 136.58; I² = 0%; 2 studies, 120 participants; very low‐certainty evidence; Analysis 1.2).

1.2. Analysis.

Comparison 1: Probiotics versus placebo, Outcome 2: Severity of Hirschsprung‐associated enterocolitis (HAEC)

Secondary outcomes

Overall mortality

El‐Sawaf 2013 reported no deaths during the study; Wang 2015 did not measure this outcome.

Withdrawals due to adverse events

El‐Sawaf 2013 reported no withdrawals due to adverse events during the study; Wang 2015 did not measure this outcome.

Recurrent episodes of HAEC

One study measured recurrent episodes of HAEC (El‐Sawaf 2013). There was little to no difference in recurrent episodes of HAEC between children treated with probiotics and placebo (OR 0.85, 95% CI 0.24 to 3.00; 1 study, 60 participants; low‐certainty evidence; Analysis 1.3).

1.3. Analysis.

Comparison 1: Probiotics versus placebo, Outcome 3: Recurrent episodes of Hirschsprung‐associated enterocolitis (HAEC)

Discussion

Summary of main results

We found that the evidence for the efficacy and safety of probiotics in Hirschsprung‐associated enterocolitis (HAEC) was sparse. We included only two relevant trials with 122 randomised and 120 analysed participants. The studies used different formulations and doses of probiotics for different durations of treatment. It is uncertain whether probiotics are better than placebo for the prevention of HAEC, because the available evidence was of low to very low certainty across all outcomes.

Compared to placebo, probiotics may make little or no difference to the:

1. occurrence of HAEC (very low‐certainty evidence);

2. severity of HAEC for children at Grade I (low‐certainty evidence), Grade II (very low‐certainty evidence), or Grade III (low‐certainty evidence);

3. number of overall deaths, or withdrawals due to adverse events or serious adverse events; or

4. number of recurrent episodes of HAEC (low‐certainty evidence).

Overall completeness and applicability of evidence

The completeness and applicability of the evidence was hampered by unexplained heterogeneity and poor documentation of the probiotic strains. Notably, pooling data from studies using a variety of species, doses, and duration of therapy in final analyses may have contributed to the heterogeneity. The effect of probiotics is probably species‐specific and dose‐dependent, since the survival rate varies greatly among different species during gastrointestinal transit, the therapeutic effect of a certain strain can not attribute to the whole group or other probiotics (Floch 2015). The included trials predominantly used VSL#3 (a commercial probiotic mixture) and a combination of Bifidobacterium, Lactobacillusacidophilus, and Enterococcus triple viable capsules as placebo. In addition, participants varied across the included studies (infants, children). Ideally, these differences should be considered, but we were limited by the small number of studies.

Another limitation to the completeness of our results is the lack of reporting of recurrent episodes of HAEC. As a recurrent disease, improvement in HAEC symptoms appears to be detected when taking probiotics continuously for a long time. However, the follow‐up duration of included studies was relatively short, and only one study measured this outcome (El‐Sawaf 2013).

The final issue is the reporting of serious adverse events. Although there are case reports of fungaemia and bacterial sepsis caused by probiotic organisms in the biomedical literature (Land 2005; Santino 2014), it is noteworthy that both included studies reported the absence of serious adverse events associated with the intervention during the study period. In summary, from the available data, it is not possible to draw a firm conclusion that probiotic supplementation is associated with an overall benefit for HAEC.

Certainty of the evidence

Overall, the identified evidence did not permit a strong conclusion to be reached on the efficacy of probiotics for HAEC. We judged that both included studies were overall, at an unclear risk of bias, since we found an unclear risk of bias for one or more key domains, especially for allocation concealment and blinding of outcome assessment. The paucity of studies prohibited further sensitivity analysis to explore the robustness of the results.

Using GRADE criteria, we categorised the certainty of the evidence for outcomes of interest as low to very low (Table 1). We downgraded the certainty of the evidence for the two primary outcomes three times: due to methodological limitations, substantial statistical heterogeneity, and small simple size for the occurrence of HAEC; and due to the low number of events, inconsistency, and imprecision of the pooled estimate for the severity of HAEC. This grading implies that we are uncertain about the estimates of effect.

Potential biases in the review process

In order to reduce the impact of publication bias, we rigorously followed the methods in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2020). We sought to capture all relevant published studies by conducting a comprehensive and systematic database search, and contacted trial investigators for additional information. However, we could not generate funnel plots to assess potential bias amongst studies, or conduct prespecified subgroup analysis for age, sex, types of probiotics, and types of Hirschsprung's disease (HD), due to the small number of included studies. This largely limited the clinical applicability of probiotics.

There were some post hoc changes in this review compared to the original protocol, and we acknowledge that these changes may have introduced potential bias in the review process (see Differences between protocol and review). For the review, we added 'severity of HAEC' as an additional primary outcome, after consultation with clinical experts. We believe this is an important issue for clinicians, which could reflect on the effectiveness of probiotics for different severity levels of HAEC, and the ability of probiotics to reduce the severity of HAEC.

Agreements and disagreements with other studies or reviews

The main findings of our review are broadly in agreement with the recent meta‐analysis by Nakamura 2018. Our review differed from others by only including RCTs, assessing other important clinical outcomes, and conducting a formal GRADE assessment to help inform practice and research. Although the available data do not support the routine use of probiotics for HAEC, probiotics have been shown to be effective in the treatment of ulcerative colitis and other gastrointestinal diseases by modulating the enteric microbiome (Derwa 2017; Ganji‐Arjenaki 2018).

Our findings suggest that the current evidence is limited and uncertain, and does not enable us to draw any precise conclusion.

Authors' conclusions

Implications for practice.

The current evidence neither supports nor refutes the benefits of probiotics over placebo on the occurrence, severity, or recurrence of Hirschsprung‐associated enterocolitis for children with Hirschsprung disease. We are also very uncertain about the associated adverse events of taking probiotics.

Implications for research.

This review highlighted the need for further well‐designed and sufficiently powered randomised controlled trials (RCTs) to assess the effect and safety of this intervention. Further studies should:

1. report methodological details regarding randomisation procedures, blinding, and withdrawals to ensure that a thorough risk of bias assessment can be done;

2. take careful consideration of strain specificity, dosing, and the best time to begin probiotic supplementation, because the standardised dose of probiotic preparation is still unclear; and

3. provide a thorough report of adverse events, which is essential to advance knowledge in this area.

History

Protocol first published: Issue 8, 2020

Appendices

Appendix 1. Clinical grading of Hirschsprung‐associated enterocolitis (HAEC)

Grade I: possible HAEC

• Mild explosive diarrhoea

• Mild to moderate abdominal distension

• No significant systemic manifestations (fever, anorexia, weight loss, tachycardia)

Grade II: mild to moderate HAEC

• Moderate explosive diarrhoea

• Moderate to severe abdominal distention

• Associated with mild to moderate systemic manifestations

Grade III: severe HAEC

• Explosive diarrhoea

• Marked abdominal distention

• Hypotension, shock, or impending shock

• Marked abdominal distention

Appendix 2. Search strategies

CENTRAL

#1 MeSH descriptor: [probiotics] explode all trees

#2 (probiotics OR lactobacillus OR bifidobacterium OR streptococcus thermophiles OR saccharomyces):ti,ab,kw

#3 #1 OR #2

#4 (Hirschsprung enterocolitis OR Hirschsprung's enterocolitis OR Hirschsprung's associated enterocolitis OR Hirschsprung associated enterocolitis):ti,ab,kw

#5 #3 AND #4

PubMed

#1 randomized controlled trial [pt]

#2 controlled clinical trial [pt]

#3 randomized [tiab]

#4 placebo [tiab]

#5 clinical trials as topic [mesh: noexp]

#6 randomly [tiab]

#7 trial [ti]

#8 #1 or #2 or #3 or #4 or #5 or #6 or #7

#9 humans [mh]

#10 #8 and #9

#11 Hirschsprung enterocolitis [Title/Abstract] OR Hirschsprung's enterocolitis [Title/Abstract] OR Hirschsprung's associated enterocolitis [Title/Abstract] OR Hirschsprung associated enterocolitis [Title/Abstract]

#12 probiotics [MeSH]

#13 probiotic [Title/Abstract] OR lactobacillus [Title/Abstract] OR bifidobacterium [Title/Abstract] OR streptococcus thermophiles [Title/Abstract] OR saccharomyces [Title/Abstract]

#14 #12 OR #13

#15 #10 AND #11 AND #14

Embase Ovid

#1 random*

#2 placebo*

#3 doubl* adj blind*

#4 singl* adj blind*

#5 assign*

#6 allocat*

#7 "double‐blind procedure"/exp

#8 "randomized controlled trial"/exp

#9 "single‐blind procedure"/exp

#10 #1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9

#11 "Hirschsprung enterocolitis OR Hirschsprung's enterocolitis OR Hirschsprung's associated enterocolitis OR Hirschsprung associated enterocolitis"

#12 probiotics /exp

#13 "probiotic OR lactobacillus OR bifidobacterium OR streptococcus thermophiles OR saccharomyces"

#14 #12 OR #13

#15 #10 AND #11 AND #14

China BioMedical Literature database

序号	检索表达式	结果	时间
#3	(#2) AND (#1)	7	10:13:05
#2	益生菌	4520	10:12:48
#1	巨结肠	3654	10:12:33

WHO ICTRP

(“Hirschsprung enterocolitis” OR “Hirschsprung's enterocolitis” OR “Hirschsprung's associated enterocolitis” OR “Hirschsprung associated enterocolitis”) AND (“probiotics”)

ChiCTR

益生菌 ｜ 巨结肠

ANZCTR

Health condition(s) or problems studied: Hirschsprung enterocolitis OR Hirschsprung's enterocolitis OR Hirschsprung's associated enterocolitis OR Hirschsprung associated enterocolitis

Description of intervention(s): probiotics

Study type: Interventional

CTRI

Hirschsprung associated enterocolitis AND probiotics

ClinicalTrials.gov

Condition or Disease: Hirschsprung enterocolitis OR Hirschsprung's enterocolitis OR Hirschsprung's associated enterocolitis OR Hirschsprung associated enterocolitis

Intervention/Treatment: probiotics

Applied Filter: Interventional studies

Study type: Interventional studies ( clinical trials)

Data and analyses

Comparison 1. Probiotics versus placebo.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Occurence of Hirschsprung‐associated enterocolitis (HAEC)	2	120	Odds Ratio (M‐H, Random, 95% CI)	0.58 [0.10, 3.43]
1.2 Severity of Hirschsprung‐associated enterocolitis (HAEC)	2	360	Odds Ratio (M‐H, Random, 95% CI)	0.66 [0.18, 2.40]
1.2.1 Grade I	2	120	Odds Ratio (M‐H, Random, 95% CI)	0.66 [0.14, 3.16]
1.2.2 Grade II	2	120	Odds Ratio (M‐H, Random, 95% CI)	1.14 [0.01, 136.58]
1.2.3 Grade III	2	120	Odds Ratio (M‐H, Random, 95% CI)	0.43 [0.05, 3.45]
1.3 Recurrent episodes of Hirschsprung‐associated enterocolitis (HAEC)	1	60	Odds Ratio (M‐H, Fixed, 95% CI)	0.85 [0.24, 3.00]

Characteristics of studies

Characteristics of included studies [ordered by study ID]

El‐Sawaf 2013.

Study characteristics
Methods	Study design: prospective, double‐blind, placebo‐controlled, randomised trial Location: USA and Egypt Setting: hospital
Participants	Sample size: 62 participants Sample calculation: "based on previous published series of Hirschsprung‐associated enterocolitis (HAEC), we modelled the study anticipating that probiotic prophylaxis would reduce the incidence of HAEC) from 40% in the placebo group to 10% in the treatment group. A model that tests the equality of two binomial probabilities was used, based on the estimated treatment effect and a power of 0.80. Specifically, this power analysis showed that we can achieve the desired power with sample sizes of 40 per group, using a one‐sided test with α = 0.05." Number of dropouts/withdrawals: 2 participants Age at diagnosis(mean ±SD): 32 ± 7.6 months (probiotic); 28 ± 4.9 months (placebo) Sex(M/F): 25:3 (probiotic); 18:14 (placebo) Long‐segment aganglionosis (%): 25% (probiotic); 19% (placebo) Diagnostic criteria: confirmed by suction rectal biopsy results prior to surgical pullthrough Inclusion criteria: all children suffering from Hirschsprung's disease (HD) at 48 months or younger Exclusion criteria: children > 48 months old at time of pullthrough, haemodynamically unstable, active septicaemia, major congenital anomalies with markedly shortened life expectancy, or an inability to tolerate or take the oral probiotics
Interventions	Intervention (N = 32): VSL#3; the probiotic was diluted in 2 oz to 4 oz of expressed human milk or formula. Study participants were administered either VSL#3 or maize starch orally, twice a day. Dosing of probiotic: based on body weight. Children < 5 kg received 90 billion bacteria (1 x 0.25 g sachet/dose) twice a day, and those over 5 kg received 180 billion bacteria (two sachets/dose) twice a day. Type of probiotic:Lactobacillus, Bifidobacterium, Streptococcus Control (N = 30): maize starch Duration of intervention: not reported
Outcomes	Primary outcomes: the occurrence of HAEC Secondary outcomes: number of HAEC episodes; the clinical severity of HAEC; associated contributing factors predisposing to HAEC (e.g. gender, a diagnosis of Trisomy 21, length of aganglionosis, age at diagnosis, and age at pullthrough procedure) Timing of measurements: 1, 3, 6, and 12 months
Notes	Study start date: January 2006 Study end date: December 2009 Clinical trials record: NCT00630838 Funding source: funded by Pharmaceuticals Inc., Sigma‐Tau Pharmaceuticals, Inc, Townson, MD Conflict of interest: none
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Block randomisation with a randomly chosen block size of 2 or 4 within center was used." Comment: adequately done
Allocation concealment (selection bias)	Unclear risk	Quote: "Randomization tables and envelopes were generated by the Department of Biostatistics at the University of Michigan and were distributed to each site." Comment: methods of concealment were not clearly stated
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "double‐blinding.The dispensed medication was coded related to the patient ID, and these codes were kept from the treating physicians and patient's parents. Randomization tables and envelopes were generated by the Department of Biostatistics at the University of Michigan and were distributed to each site." Comment: adequately done
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: there were no details on whether outcome assessment was blinded, and no response to email.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: the total amount of attrition was less than 20%. Reason for loss to follow‐up: early post‐pullthrough death from unrelated causes; one was dropped due to complete noncompliance.
Selective reporting (reporting bias)	Low risk	Comment: the intended outcomes specified in the methods were reported and these were as expected.
Other bias	Low risk	Comment: although the study was funded by the manufacturers of the probiotics studied in this article, the authors declared no influence on the results.

Wang 2015.

Study characteristics
Methods	Study design: a prospective, multicentre, randomised controlled trial Location: Department of Pediatric Surgery, Tongji Hospital; The First Hospital of Harbin Medical University; and Anhui Provincial Hospital Setting: hospital
Participants	Sample size: 60 participants Sample calculation: no power calculation Number of dropouts/withdrawals: none Age at diagnosis (mean ± SD): 12.63 ± 9.86 months (probiotic); 11.64 ± 8.67 months (placebo) Sex(M/F): 14:16 (probiotic); 17:13 (placebo) Long‐segment aganglionosis (%): 33% (probiotic); 37% (placebo) Diagnostic criteria: confirmed by barium enema, anorectal manometry, and postoperative pathological examination Inclusion criteria: all children suffering from HD who were younger than 18 years old Exclusion criteria: Age >18 years old; children who were complicated with mental and neurological disorders; other congenital gastrointestinal malformations; liver, kidney dysfunction, blood disorders, immune deficiency diseases, and significant ECG abnormalities; children who had been given oral antibiotics, microecological modulator, yogurt, or other gastrointestinal motility drugs which could affect the gut flora; drug allergies or allergic diseases; poor compliance with oral probiotic treatment
Interventions	Intervention (N = 28): oral Bifido Dose of probiotic: based on body weight, 1.0 × 10⁸ CFU Type of probiotic:Lactobacillus, Bifidobacterium, Enterococcus Control (N = 32): maize starch Duration of intervention: 4 weeks
Outcomes	Primary outcomes: incidence of HAEC; severity of HAEC; CD4⁺, CD8⁺,T lymphocyte flow cytometry Timing of measurements: 3 months
Notes	Study start date: January 2008 Study end date: January 2010 Clinical trials record: NCT01934959 Funding source: funded by National Key Specialty Construction Program (2013544) and National Natural Science Foundation of China (PI:Zhi Li;No:81400579) Conflict of interest: not specified
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Patients who conform to the inclusion criteria will be randomly and equally assigned into the treatment group and the control group with random number table row randomisation." Comment: adequately done
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient information on which to base judgement
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Both compounds were indistinguishable in appearance after conventional treatment." Comment: adequately done
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: insufficient information on which to base judgement
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: no loss to follow‐up
Selective reporting (reporting bias)	Low risk	Comment: The intended outcomes specified in the methods were reported and these were as expected.
Other bias	Low risk	Comment: No other apparent biases

CFU: colony‐forming units; ECG: electrocardiograph; HD: Hirschsprung's disease; HAEC: Hirschsprung‐associated enterocolitis

Characteristics of excluded studies [ordered by study ID]

Study	Reason for exclusion
Demehri 2015	Ineligible study design – case‐control study
Frykman 2015	Ineligible study design – case‐control study
Li 2016	Ineligible study design – review article
Liang 2013	Ineligible study design – case‐control study
Nakamura 2018	Ineligible study design – review article
Qu 2010	Ineligible study design – review article
Soh 2018	Ineligible study design – review article
Xia 2010	Ineligible population – the study included participants with Clostridium difficile‐associated diarrhoea
Yin 2011	Ineligible study design – clinical control article
Zheng 2011	Ineligible study design – review article
Zhou 2008	Ineligible population – the study included participants with fulminant attack of ulcerative colitis
Zhu 2014	Ineligible population – the study included participants with pseudomembranous colitis

Characteristics of ongoing studies [ordered by study ID]

NCT02343562.

Study name	Probiotics for prophylaxis of postoperative Hirschsprungs‐associated enterocolitis
Methods	RCT, triple‐blind, parallel assignment
Participants	Inclusion criteria: Hirschsprungs disease confirmed preoperative and postoperative specimen pathology Exclusion criteria: other cases of enterocolitis and constipation
Interventions	Intervention: probiotics in the form of sachet will be given twice daily for a period of at least 6 months during the trial period Control: placebo ‐ multivitamin over‐the‐counter
Outcomes	Primary outcome measures Prevention of HAEC (time frame: 6 months) Absence of HAEC symptoms and signs; absence of fever, abdominal distension, loose stools (diarrhoea), bloody stools during the postoperative period for 6 months Secondary outcome measures Improvement of stooling pattern of postoperative HAEC cases (time frame: 6 months) Bowel habits and motion data are recorded at base line (start of the study) and measured throughout the study. Number of motions per day, stool consistency and periodic culture and sensitivity analysis of the stools. Improvement is measured by optimising stool output to 2‐3 times daily, stool consistency according to age should be semi‐solid to solids. Stool analysis improvement criteria include better consistency, absence of pus cells or red blood cells and no growth on culture for pathogenic bacteria.
Starting date	October 2014
Contact information	Mahmoud MA Elfiky, M.D. +201001557755 mfiky@kasralainy.edu.eg； Mostafa A Gad +201002265009 mostafagad@kasralainy.edu.eg
Notes	Sponsors and collaborators: Cairo University

HAEC: Hirschsprung‐associated enterocolitis

Differences between protocol and review

We made some changes to the protocol, as follows.

1. We added severity of Hirschsprung‐associated enterocolitis (HAEC) as a primary outcome measure after discussions with clinicians; this was reported by both included studies, and therefore, considered important to include in the final review.

2. We only included randomised controlled trials (RCTs) to enhance the strength of the evidence.

3. We did not perform subgroup analysis based on age, gender, country, types of probiotics, and types of Hirschsprung's disease (HD) because of the small number of included studies.

4. We did not conduct a sensitivity analysis because we assessed the overall risk of bias of the included studies as unclear.

Contributions of authors

FM: conception of the review, design of the review, search and selection of studies for inclusion in the review, analysis of data, writing of the review

MW: collection of data for the review, assessment of the certainty of the body of evidence

LZ: assessment of the risk of bias in the included studies, collection of data for the review

KH: assessment of the certainty of the body of evidence

QG: collection of data for the review

FC: search and selection of studies for inclusion in the review

YW: assessment of the risk of bias in the included studies

JSWK: interpretation of data

XS: analysis of data

BM: design of the review, interpretation of data

Sources of support

Internal sources

• Natural Science Foundation of China (NSFC), China

  This work is funded by the National Natural Science Foundation of China (81873184).

External sources

• No sources of support provided

Declarations of interest

FM: none known

MW: none known

LZ: none known

KH: none known

QG: none known

FC: none known

YW: none known

JSWK: none known

XS: none known

BM: none known

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