Critically ill patients may benefit from probiotics, but evidence is weak

Patients with thrombocytosis in the setting of community-acquired pneumonia (CAP) are at higher risk of poor outcome, complicated pleural effusion and empyema than those with a normal platelet count, a study found.

Researchers searched databases, article reference lists, and personal files from 1980 to 2011. Their review included 23 randomized controlled trials that evaluated use of probiotics versus placebo in critically ill adults for outcomes including infections (primary) and mortality and length of stay (secondary). Subgroup analyses were performed to compare high and low doses of probiotics, different strains of probiotics, and methodological quality of studies. Results were published Sept. 12 in Critical Care Medicine.

The mean methodological score of all trials was 9.5 (range, 6 to 13) of a possible 14. Of the 23 trials, seven (30%) tested the viability of the probiotics used in the intervention.

Different probiotic therapies were used among the 23 included trials; eight used Lactobacillus plantarum and three used Lactobacillus rhamnosus strain GG.

In the 11 trials that reported infectious complications, pooled results show that probiotics were associated with a reduction in such complications (risk ratio [RR], 0.82; P=0.03). Pooled data from the seven trials reporting VAP data found a significant reduction in VAP rates associated with probiotics (RR, 0.75; P=0.03). Probiotics were associated with a non-significant trend toward reduced ICU mortality (RR, 0.80; P=0.16) but had no effect on hospital mortality or length of stay in the ICU or hospital. More dramatic treatment effects were seen in trials of lower methodological quality.

The findings in this analysis were "tempered by the presence of significant clinical and statistical heterogeneity and the lack of statistical precision in some analyses," the authors noted, and were further weakened by the fact that more dramatic results were found in the lower-quality trials. The results are, however, consistent with a 2009 review that suggested probiotics reduce VAP. Other than one study from 2010, this review didn't find an association between probiotic use and fewer cases of diarrhea, they noted, similar to many previous studies. The best type and dosage of probiotics also were not clear from this analysis, they wrote.

A separate meta-analysis of 13 trials, published in the Sept. 10 Chest, found that probiotics didn't significantly reduce hospital or ICU mortality or the duration of mechanical ventilation. Probiotics were, however, associated with lower incidence of ICU-acquired pneumonia and a shorter stay in the ICU.