Probiotics may prevent acute upper respiratory infection in children

Resident Focus - Volume 12, Issue 3

Probiotics for preventing acute upper respiratory tract infections. Hao Q, Dong BR, Wu T, Cochrane Database Syst Rev. 2015 Feb 3;(2):CD006895

Level 2 (mid-level) evidence

A healthy middle aged woman complains of cough, fever, nasal congestion and runny nose for the past 3 days. After a reassuring physical exam, you diagnose the patient with an acute upper respiratory infection (URI) and advise supportive treatment. Your patient is worried about spreading the infection to her family. She has heard that probiotics may prevent URI, and she asks if “they really work”.
This Cochrane review included a systematic review of the medical literature and identified 13 randomized controlled trials of probiotics in patients with URI with 3,780 patients; 12 studies had data extracted for meta-analysis. There were 8 trials of 2,571 children, 3 trials of 995 adults aged 18-65 years, and 2 trials of 214 older adults. The trials were conducted in various countries including Chile, Croatia, Finland, Japan, Spain, Sweden, Thailand, and the United States. The participants received either probiotics for more than seven days, placebo or no treatment. Most of the studies were of low quality due to unclear randomization methods and blinding as well as small sample sizes. There was also a high level of clinical heterogeneity due to different outcome measures, single or mixture of probiotic strains at various dosage regimens and routes of administration, and varied patient populations.

Probiotics reduced the number of patients experiencing one acute URI (odds ratio [OR] 0.53, 95% CI 0.37- 0.76; NNT 6-18) in analysis of 7 trials with 1,927 patients. This benefit was seen when all studies were combined and when only children were analyzed, but not in the single study of adults and the single study of older adults. Probiotics also reduced the number of patients who experienced at least three acute URIs (OR 0.53, 95% CI 0.36- 0.81, NNT 6-24) in analysis of 3 trials with 650 patients. The duration of an acute URI episode was reduced by a mean difference of 1.89 days (95% CI 1.75-2.04 days) in analysis of 3 studies with 768 adults. Probiotics also reduced both antibiotic prescription rates (RR 0.65, 95% CI 0.45-0.94, NNT 19-184) in analysis of 4 trials with 1,184 patients, and URI-related school absences (OR 0.10, 95% CI 0.02- 0.47, NNT 3-5) in analysis of 1 trial with 80 patients. Adverse events were similar between groups and only minor side effects were noted (most commonly gastrointestinal symptoms).

This Cochrane review demonstrates that probiotics may prevent acute URI in children, and they may also help in reducing the duration of acute URI in adults. In addition, they may decrease the number of school absences and reduce antibiotic prescription rates. However, the studies were clinically heterogeneous, and some results had wide confidence intervals (including the possibility of no clinically significant difference). The heterogeneity also means that no specific probiotic formulation can be currently recommended. More high-quality randomized trials are needed to confirm and refine these conclusions.

For more information, see the Upper respiratory infection (URI) in children topic in Dynamed Plus. DynaMed users click here.