Starting probiotics within 2 days of the first antibiotic dose could cut the risk of Clostridium difficile infection among hospitalized adults by more than 50%, according to the results of a systemic review and metaregression analysis.
The protective effect waned when patients delayed starting probiotics, reported Nicole T. Shen, MD, of Cornell University, New York, and her associates. The study appears in Gastroenterology (doi: 10.1053/j.gastro.2017.02.003). “Given the magnitude of benefit and the low cost of probiotics, the decision is likely to be highly cost effective,” they added.
Systematic reviews support the use of probiotics for preventing Clostridium difficile infection (CDI), but guidelines do not reflect these findings. To help guide clinical practice, the reviewers searched MEDLINE, EMBASE, the International Journal of Probiotics and Prebiotics, and the Cochrane Library databases for randomized controlled trials of probiotics and CDI among hospitalized adults taking antibiotics. This search yielded 19 published studies of 6,261 patients. Two reviewers separately extracted data from these studies and examined quality of evidence and risk of bias.
A total of 54 patients in the probiotic cohort (1.6%) developed CDI, compared with 115 controls (3.9%), a statistically significant difference (P less than .001). In regression analysis, the probiotic group was about 58% less likely to develop CDI than controls (hazard ratio, 0.42; 95% confidence interval, 0.30-0.57; P less than .001). Importantly, probiotics were significantly effective against CDI only when started within 2 days of antibiotic initiation (relative risk, 0.32; 95% CI, 0.22-0.48), not when started within 3-7 days (RR, 0.70, 95% CI, 0.40-1.23). The difference between these estimated risk ratios was statistically significant (P = .02).
In 18 of the 19 studies, patients received probiotics within 3 days of starting antibiotics, while patients in the remaining study could start probiotics any time within 7 days of antibiotic initiation. “Not only was [this] study unusual with respect to probiotic timing, it was also much larger than all other studies, and its results were statistically insignificant,” the reviewers wrote. Metaregression analyses of all studies and of all but the outlier study linked delaying probiotics with a decrease in efficacy against CDI, with P values of .04 and .09, respectively. Those findings “suggest that the decrement in efficacy with delay in starting probiotics is not sensitive to inclusion of a single large ‘outlier’ study,” the reviewers emphasized. “In fact, inclusion only dampens the magnitude of the decrement in efficacy, although it is still clinically important and statistically significant.”
The trials included 12 probiotic formulas containing Lactobacillus, Saccharomyces, Bifidobacterium, and Streptococcus, either alone or in combination. Probiotics were not associated with adverse effects in the trials. Quality of evidence was generally high, but seven trials had missing data on the primary outcome. Furthermore, two studies lacked a placebo group, and lead authors of two studies disclosed ties to the probiotic manufacturers that provided funding.
One reviewer received fellowship support from the Louis and Rachel Rudin Foundation. None had conflicts of interest.