Study Title:

Probiotics for Diarrhea

Study Abstract

BACKGROUND: Probiotics may offer a safe intervention in acute infectious diarrhoea to reduce the duration and severity of the illness.

OBJECTIVES: To assess the effects of probiotics in proven or presumed acute infectious diarrhoea.

SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group's trials register (July 2010), the Cochrane Controlled Trials Register (The Cochrane Library Issue 2, 2010), MEDLINE (1966 to July 2010), EMBASE (1988 to July 2010), and reference lists from studies and reviews. We also contacted organizations and individuals working in the field, and pharmaceutical companies manufacturing probiotic agents.

SELECTION CRITERIA: Randomized and quasi-randomized controlled trials comparing a specified probiotic agent with a placebo or no probiotic in people with acute diarrhoea that is proven or presumed to be caused by an infectious agent.

DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed the methodological quality of the trial and extracted data. Primary outcomes were the mean duration of diarrhoea, stool frequency on day 2 after intervention and ongoing diarrhoea on day 4. A random-effects model was used.

MAIN RESULTS: Sixty-three studies met the inclusion criteria with a total of 8014 participants. Of these, 56 trials recruited infants and young children. The trials varied in the definition used for acute diarrhoea and the end of the diarrhoeal illness, as well as in the risk of bias. The trials were undertaken in a wide range of different settings and also varied greatly in organisms tested, dosage, and participants' characteristics. No adverse events were attributed to the probiotic intervention.Probiotics reduced the duration of diarrhoea, although the size of the effect varied considerably between studies.The average of the effect was significant for mean duration of diarrhoea (mean difference 24.76 hours; 95% confidence interval 15.9 to 33.6 hours; n=4555, trials=35) diarrhoea lasting ≥4 days (risk ratio 0.41; 0.32 to 0.53; n=2853, trials=29) and stool frequency on day 2 (mean difference 0.80; 0.45 to 1.14; n=2751, trials=20).The differences in effect size between studies was not explained by study quality, probiotic strain, the number of different strains, the viability of the organisms, dosage of organisms, the causes of diarrhoea, or the severity of the diarrhoea, or whether the studies were done in developed or developing countries.

AUTHORS' CONCLUSIONS: Used alongside rehydration therapy, probiotics appear to be safe and have clear beneficial effects in shortening the duration and reducing stool frequency in acute infectious diarrhoea. However, more research is needed to guide the use of particular probiotic regimens in specific patient groups.

From press release:

Probiotic bacteria given as therapies for diarrhea reduce the length of time sufferers are affected and lessen the chance of episodes continuing for more than four days. These are the findings of a new systematic review by Cochrane researchers.

Every year, diarrheal diseases kill nearly two million people in developing countries, mostly young children. The main treatment is rehydration fluids, but these do not tend to reduce the length of illness, which is crucial in reducing the risk of persistent diarrhea. Probiotics, so-called "good bacteria," may help in a variety of different ways including eliminating the bacteria, viruses or parasites responsible, for example, by competing for the same nutrients. A previous Cochrane review showed benefits with probiotics in diarrheal disease, but the current report reviews data from a far larger evidence base.

The researchers reviewed data from 63 trials involving a total of 8,014 patients, over four times the number involved in the previous study. 56 trials focused on infants and young children. Giving probiotics in conjunction with rehydration fluids reduced the duration of diarrhea by around a day and reduced the risk of diarrhea lasting four or more days by 59%. No serious adverse effects were reported in the trials and although vomiting was quite common it also occurred with placebos.

"A striking finding of this review is that most trials reported that probiotics reduced diarrhea," said lead researcher Stephen Allen of the School of Medicine at Swansea University, UK. "The beneficial effect was consistent and significant across many different types of trials."

"There were no adverse effects, so these therapies can be used safely in addition to rehydration fluids. However, more research needs to be carried out on the specific strains of bacteria that are effective in treating diarrhea and on preventing the progression from short-term to persistent diarrhea," Allen said.

A second review, by a separate group of Cochrane researchers, examined the use of probiotics for treating persistent diarrhea reviewing data from trials undertaken exclusively in children. The review found that probiotics can reduce the length of an episode of persistent diarrhea, however, the authors stress that the review was based on just four trials involving 464 patients and therefore provides only limited evidence of benefit.

Study Information

Allen SJ, Martinez EG, Gregorio GV, Dans LF.
Probiotics for treating acute infectious diarrhea.
Cochrane Database Syst Rev.
2010 November
School of Medicine, Swansea University, Room 314, The Grove Building, Singleton Park, Swansea, West Glamorgan, UK, SA2 8PP.

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