OM-85 did not prevent wheezing illness in high-risk toddlers

Design

Randomised, double-blind, placebo-controlled trial, 11 centres

Population

822 children aged 6–18 months at high risk of asthma

Primary outcome

Time to first wheezing lower respiratory illness over 36 months off treatment

Effect

21% vs 18%; HR 1.16 (95% CI 0.82–1.64), p=0.35

ORBEX randomised 822 children aged 6 to 18 months at high risk of asthma, because of eczema, parental asthma or an older sibling with asthma, to oral OM-85 3.5 mg or placebo for 10 days each month for two years, at 11 US centres. The primary outcome was time to first wheezing lower respiratory illness in the following three years, off treatment. It was published on 7 September.

Wheezing illness occurred in 21% on OM-85 and 18% on placebo (HR 1.16, 95% CI 0.82–1.64). Adverse events did not differ. The authors conclude bacterial lysates are not effective for primary prevention of preschool asthma-like symptoms.

This matters in India, where OM-85 and other bacterial lysates are widely prescribed to children with recurrent coughs and wheeze. The trial tested primary prevention in high-risk infants; it did not test children who already wheeze, where earlier smaller trials suggested fewer episodes. But for the parent asking whether a monthly course will stop their baby developing asthma, this is a clear no.

• Do not prescribe OM-85 to infants to prevent future wheeze or asthma.
• Tell parents of high-risk infants that a two-year monthly course did not reduce wheezing illness.
• Focus prevention on smoke-free homes and routine vaccination, including influenza where recommended.
• Note that this trial did not test children who already have recurrent wheeze.

Why it matters

A widely used preventive for toddlers has been tested properly and did not work.

Don't overread it

The trial addressed primary prevention, not treatment of children who already wheeze.

The statistics, in plain English

A hazard ratio of 1.16 with an interval from 0.82 to 1.64 means the data fit anything from a modest benefit to a modest harm, centred near no effect. Wheeze was in fact slightly more common in the OM-85 group.

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