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Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and What Can Be Done About It?

Mazurak N, Broelz E, Storr M, Enck P - J Neurogastroenterol Motil (2015)

Bottom Line: Twenty-seven studies used multi-species bacterial preparations and 29 used single-strain probiotics.They were analysed regarding patients included, treatment duration, probiotic dosage, and outcome measures.The use of different bacterial strains and different mixtures of these strains, as well as different dosages, are the main contributors to this heterogeneity.

View Article: PubMed Central - PubMed

Affiliation: SymbioGruppe GmbH, Herborn, Germany.

ABSTRACT

Background/aims: Despite numerous randomized clinical trials and meta-analyses, there is no increased evidence for the efficacy of probiotics in the treatment of irritable bowel syndrome (IBS). We review this evidence, identify and analyse the reasons for this lack of evidence and propose methodological improvements for future studies.

Methods: Based on a literature search, we identified 56 papers that matched the purpose of our analyses. Twenty-seven studies used multi-species bacterial preparations and 29 used single-strain probiotics. They were analysed regarding patients included, treatment duration, probiotic dosage, and outcome measures.

Results: Trials in both groups suffered from heterogeneity with respect to probiotic concentration, duration of treatment, and other methodological issues (crossover design and underpowered studies). This heterogeneity did not allow the application of a meta-analytic approach and a systematic review was therefore performed instead. Multi-strain preparations combined 2 to 8 different bacterial subspecies, mostly lactobacilli or bifidobacteria, and used variable lengths of treatments. Overall, more than 50% of trials presented negative outcomes. The majority of the single-strain probiotic trials employing lactobacilli or Saccharomyces were negative, whereas trials employing bifidobacteria showed positive results.

Conclusions: The heterogeneity of the studies of probiotics in IBS questions the value of meta-analyses. The use of different bacterial strains and different mixtures of these strains, as well as different dosages, are the main contributors to this heterogeneity. Current data provides limited evidence for the efficacy of a small number of single-strain probiotics in IBS (mostly bifidobacteria) and sound studies following strict trial guidelines (Food and Drug Administration and European Medicines Agency guidelines for clinical trials) are needed. We summarised and proposed some methodological issues for future studies in the field.

No MeSH data available.


Related in: MedlinePlus

Preferred reporting items for systematic reviews and meta-analyses (PRISMA) scheme of retrieved literature.
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f1-jnm-21-471: Preferred reporting items for systematic reviews and meta-analyses (PRISMA) scheme of retrieved literature.

Mentions: Step 1: Figure 1 shows the results of the literature search, last performed on April 20, 2015. After exclusion of systematic reviews and meta-analyses (n = 9), uncontrolled trials (n = 20), narrative reviews, editorial, letters and comments (n = 78), animal research (n = 2), studies of children and respective reviews (n = 10), non-English papers and studies (n = 8), and others (n = 8), 60 studies remained. Data published in abstract form only was not included.


Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and What Can Be Done About It?

Mazurak N, Broelz E, Storr M, Enck P - J Neurogastroenterol Motil (2015)

Preferred reporting items for systematic reviews and meta-analyses (PRISMA) scheme of retrieved literature.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4622129&req=5

f1-jnm-21-471: Preferred reporting items for systematic reviews and meta-analyses (PRISMA) scheme of retrieved literature.
Mentions: Step 1: Figure 1 shows the results of the literature search, last performed on April 20, 2015. After exclusion of systematic reviews and meta-analyses (n = 9), uncontrolled trials (n = 20), narrative reviews, editorial, letters and comments (n = 78), animal research (n = 2), studies of children and respective reviews (n = 10), non-English papers and studies (n = 8), and others (n = 8), 60 studies remained. Data published in abstract form only was not included.

Bottom Line: Twenty-seven studies used multi-species bacterial preparations and 29 used single-strain probiotics.They were analysed regarding patients included, treatment duration, probiotic dosage, and outcome measures.The use of different bacterial strains and different mixtures of these strains, as well as different dosages, are the main contributors to this heterogeneity.

View Article: PubMed Central - PubMed

Affiliation: SymbioGruppe GmbH, Herborn, Germany.

ABSTRACT

Background/aims: Despite numerous randomized clinical trials and meta-analyses, there is no increased evidence for the efficacy of probiotics in the treatment of irritable bowel syndrome (IBS). We review this evidence, identify and analyse the reasons for this lack of evidence and propose methodological improvements for future studies.

Methods: Based on a literature search, we identified 56 papers that matched the purpose of our analyses. Twenty-seven studies used multi-species bacterial preparations and 29 used single-strain probiotics. They were analysed regarding patients included, treatment duration, probiotic dosage, and outcome measures.

Results: Trials in both groups suffered from heterogeneity with respect to probiotic concentration, duration of treatment, and other methodological issues (crossover design and underpowered studies). This heterogeneity did not allow the application of a meta-analytic approach and a systematic review was therefore performed instead. Multi-strain preparations combined 2 to 8 different bacterial subspecies, mostly lactobacilli or bifidobacteria, and used variable lengths of treatments. Overall, more than 50% of trials presented negative outcomes. The majority of the single-strain probiotic trials employing lactobacilli or Saccharomyces were negative, whereas trials employing bifidobacteria showed positive results.

Conclusions: The heterogeneity of the studies of probiotics in IBS questions the value of meta-analyses. The use of different bacterial strains and different mixtures of these strains, as well as different dosages, are the main contributors to this heterogeneity. Current data provides limited evidence for the efficacy of a small number of single-strain probiotics in IBS (mostly bifidobacteria) and sound studies following strict trial guidelines (Food and Drug Administration and European Medicines Agency guidelines for clinical trials) are needed. We summarised and proposed some methodological issues for future studies in the field.

No MeSH data available.


Related in: MedlinePlus