JAMA 2012;307:1959-69 [PubMed® abstract]
More evidence that probiotics can help prevent diarrhoea associated with antibiotics has emerged from a meta-analysis of randomised trials. The authors found 82 trials after a systematic search but only 63 reported how many people took the probiotics, how many took the control treatment, and how many developed diarrhoea. Across these 63 trials, probiotics were associated with a 42% reduction in the risk of diarrhoea (relative risk 0.58, 95% CI 0.50 to 0.68; number needed to treat 13, 10.3 to 19.1).
Most trials tested probiotic preparations containing lactobacilli, alone or in mixed cultures. The effect looked consistent in multiple different analyses, including two confined to high quality trials and another that looked specifically at adults taking antibiotics for Helicobacter pylori infections (the most commonly reported indication). The authors are confident their results are as robust as they can be given the generally poor quality of the evidence base.
Most trials were underpowered and badly reported. It is still hard to know the precise mix of micro-organisms that is likely to work best and the characteristics of patients most likely to benefit. Details of the antibiotics being taken were missing from many trials, as were reliable assessments of side effects. Still, we have enough encouraging evidence to justify further research to fine tune these results, say the authors. Diarrhoea associated with antibiotics is common and can be life threatening.