Probiotics Do Not Prevent URTIs in Those With Asthma

Troy Brown, RN

September 15, 2016

Daily probiotic use does not reduce winter antibiotic prescriptions for upper respiratory tract infections (URTIs) in patients with asthma, according to results from a randomized controlled, parallel-group pragmatic study.

"These results differ from previous findings in controlled trials mainly involving younger children that probiotics reduce respiratory tract infections and resulting antibiotic prescription rates, and they cast doubt on the reproducibility of those findings in older children and adults with asthma using information leaflets," the researchers write.

Timothy D. H. Smith, MBBCh, MRCGP, Harambee Surgery, National Health Service East Lancashire Clinical Commissioning Group, United Kingdom, and colleagues report their findings in an article published in the September/October issue of the Annals of Family Medicine.

A 2011 Cochrane review suggested that probiotic prophylaxis significantly reduced URTIs and antibiotic prescriptions for URTIs in randomized controlled trials of specific populations. One small pilot study in patients with asthma found that probiotics in combination with acupuncture reduced respiratory infection rates, but the study was underpowered (n = 17), and the results were not statistically significant (P = .18).

"Probiotics alone for preventing antibiotic use in asthmatics have not, to our knowledge, been evaluated in a prospective controlled trial," the authors write. "We undertook a pragmatic trial to assess whether advice to take probiotic treatment, implemented as part of routine winter infection advice, could reduce antibiotic prescription rates and respiratory tract infections in older children and adults with asthma in a primary care setting."

All patients with asthma in the United Kingdom are invited to receive an annual influenza vaccine. The study randomly assigned patients registered in one primary care clinic to also receive a leaflet with standard advice for reducing respiratory infections and asthma exacerbations (control group; n = 650) or a leaflet with additional advice to take one probiotic capsule daily from October through March (intervention group; n = 652). The intervention group received three tokens, each good for a 2-month supply of a proprietary blend of four probiotic bacteria strains.

The study included patients aged 5 years or older because asthma diagnoses are unreliable in younger children.

Overall, there was no difference between the groups in prescriptions for a specified antibiotic during the study period in an intention-to-treat analysis (odds ratio [OR], 1.04; 95% confidence interval [CI], 0.82 - 1.34). Similarly, there was no difference detected when the researchers restricted their analysis to those participants in the probiotic group who used one or more probiotic tokens (adjusted OR, 1.08; 95% CI, 0.69 - 1.69) or two or more probiotic tokens (adjusted OR, 1.04; 95% CI, 0.62 - 1.75).

Secondary outcomes (use of any antibiotic, any antibiotic given for URTI, or any respiratory tract illness, number of antibiotic courses, or total cost of antibiotics) did not differ in unadjusted or adjusted analyses.

"Although only approximately 20% of these participants followed the intervention leaflet advice and took probiotics (per protocol groups), we found no evidence that probiotics influenced study outcomes in the per protocol groups," the authors write.

"Further work is needed to evaluate whether specific probiotic formulations modulate systemic immune responses or mucosal defenses before developing new interventions to reduce the burden of respiratory tract infection," they conclude.

The authors have disclosed no relevant financial relationships.

Ann Fam Med. 2016;14:422-430. Full text

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