The bacterial lysate OM-85 did not prevent preschool wheeze

Design

Randomised, double-blind, placebo-controlled trial (ORBEX)

Population

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

Primary outcome

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

Effect

21% vs 18%, HR 1.16 (95% CI 0.82–1.64)

ORBEX was a double-blind, placebo-controlled US trial in 822 children aged 6–18 months at high risk of asthma (atopic dermatitis, parental asthma or an older sibling with asthma). They received OM-85 3.5 mg or placebo orally for 10 days each month for two years, then were followed for three years off treatment.

In the off-treatment period, 21% on OM-85 and 18% on placebo had a wheezing lower respiratory illness (HR 1.16, 95% CI 0.82–1.64). Adverse events did not differ.

Bacterial lysates are widely sold to prevent recurrent respiratory infections and wheeze in children. This trial, part-funded by the manufacturer, found no preventive benefit in the group most likely to gain.

• Do not prescribe OM-85 or other bacterial lysates to prevent wheeze or asthma in young children.
• Parents who ask about 'immune boosters' for wheezy infants can be told the largest trial was negative.
• The trial tested primary prevention; it does not address treatment of established recurrent wheeze.
• Money saved is better spent on smoke-free homes and routine vaccination.

Why it matters

It removes a widely marketed preventive from the evidence base for early-life asthma prevention.

The statistics, in plain English

The point estimate actually leans slightly the wrong way (HR 1.16), and the interval (0.82–1.64) excludes any benefit larger than about 18%.

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