Reference: Pozzoni, P., et al., Saccharomyces boulardii for the Prevention of Antibiotic-Associated Diarrhea in Adult Hospitalized Patients: A Single-Center, Randomized, Double-Blind, Placebo-Controlled Trial. Am J Gastroenterol, 2012.
A study out of Italy describing the effects of the probiotic Saccharomyces boulardii in the prevention of Antiobotic-associated diarrhea (AAD) and Clostridium difficuile-associated diarrhea (CDAD).
Brief Summary: Antibiotics can effectively be used to mitigate several Gastroentestinal diseases, but one of their negative side effects is Antibiotic-associated diarrhea (AAD) and Clostridium difficile-associated diarrhea (CDAD). In the past, probiotics have been effective used to prevent AAD and CCD. The main objective of this study was to test the effectiveness of the probiotic Saccharomyces boulardii on the occurrence of AAD and CDAD. A total of 562 patients were accrued in a double-blind, placebo controlled study. The accrued patients were assigned either the S. boulardii capsule or the placebo.
Results: The patients who received the S. boulardii capsule (the probiotic) did not incur a significant reduction in the incidence of AAD or CDAD compared to the plecebo.
Implications for Practice: Gastroenterologists should not prescribe priobiotics for the purpose of alleviating AAD or CDAC symptoms.
Discussion: Previous studies have shown that probiotics can be used to decrease the incidence of AAD and CDAC, and it is interesting that this study came out with a negative result. It is important that all results - both positive and negative – such as this one be published to increase the overall understanding.
It is interesting that the only patient characteristic found to be associated with AAD was a low level of serum creatinine. Another retrospective analysis did find an increased level of serum creatinine for patients with extreme AAD. More studies will need to be done to elucidate the cause and effect relationship between AAD and serum creatinine. It would be interesting to look at the cause and effect relationship at play here, especially on a more of a molecular biology level.
Commentary on Statistics and Study Design: The statistics and study design from this paper was well planned out. The author’s used a multi-variate logistic regression model to study the main effect between the treatment and the outcome, which is the correct model to use. The advantage of using this model – over the typical univariate statistics – is that other variables can more easily be controlled for. Also, I liked how the authors included clear and precise power calculations. And of course, the double-blind nature of the study alleviates any measurement bias concerns – always the gold standard in medicine.
As for the previous studies detailing the relationship between AAD and probiotics, the authors said that these studies have had several methodological drawbacks including “non-calculated sample size, inadequate study power, lack of generalizibility of the results due to manner of the selection of the enrolled patients, and unspecified information about the application of non-pharmacological infection control measures”. I have not had the chance to go back and read these papers in depth to verify all of this (I will in the future soon), but the author’s points are well noted – especially the concern over the manner in which the patients were selected. One of the biggest study design errors I see in medical studies such as this is a mistake in the population which is samples. In any sort-of statistical inference study, you want the population you draw from to be as similar to the general population as possible. The reason being is that the nature of the statistical relationship can differ from the general population based on the sub-set population that you draw from. This is known as a “selection bias.” It is a very difficult bias to overcome, and statisticians can only alleviate the issue as best as possible.
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