Meta-analysis: the effect of probiotic administration on antibiotic-associated diarrhoea

Background: Antibiotic-associated diarrhoea can be attributed in part to imbalances in intestinal microflora. Therefore, probiotic preparations are used to prevent this diarrhoea. However, although several trials have been conducted, no conclusive evidence has been found of the efficacy of different preparations, e.g. Lactobacillus spp. and Saccharomyces spp. Aim: To conduct a meta-analysis of the data in the literature on the efficacy of probiotics in the prevention of antibiotic-associated diarrhoea. Methods: A literature search was performed of electronic databases, Abstract Books and single paper references. Data were also obtained from the authors. Only placebo-controlled studies were included in the search. The Mantel-Haenszel test was used to estimate the relative risk for single studies and an overall combined relative risk, each study being submitted to the Mantel-Haenszel test for homogeneity. Results: Twenty-two studies matched the inclusion criteria. Only seven studies (881 patients) were homogeneous. The combined relative risk was 0.3966 (95% confidence interval, 0.27-0.57). Conclusions: The results suggest a strong benefit of probiotic administration on antibiotic-associated diarrhoea, but further data are needed. The evidence for beneficial effects is still not definitive. Published studies are flawed by the lack of a placebo design and by peculiar population features.