A bacterial lysate did not prevent wheezing illness in high-risk preschoolers

Design

Double-blind, placebo-controlled randomised trial at 11 US sites (ORBEX); 24 months of treatment, 36 months off drug

Population

822 children aged 6 to 18 months at increased risk of asthma

Primary outcome

Time to first wheezing lower respiratory tract illness during the 36-month observation period

Effect

21% vs 18% affected; HR 1.16 (95% CI 0.82 to 1.64); P = 0.35

ORBEX was a double-blind, placebo-controlled trial at 11 US sites. Children aged 6 to 18 months at increased risk of asthma (atopic dermatitis, or asthma in a parent or an older sibling) took oral OM-85 3.5 mg or placebo for 10 days each month for 24 months, then were followed for 36 months off treatment. A total of 822 children were randomised.

The primary outcome was time to first wheezing lower respiratory tract illness during the 36 months of observation. Of those followed, 71 of 342 (21%) in the OM-85 group and 61 of 339 (18%) in the placebo group had at least one such illness (hazard ratio 1.16, 95% CI 0.82 to 1.64; log-rank P = 0.35). Common adverse events, fevers, coughs and colds, did not differ.

The authors conclude that bacterial lysates are not effective for primary prevention of asthma-like symptoms in the preschool years in this population. The trial was funded by the US heart, lung and blood institute and by the manufacturer. It does not address treatment of children who already have recurrent infections, which is a different question.

• Do not start a bacterial lysate to prevent wheezing in young children at high risk of asthma.
• Tell parents who ask that this large trial found no reduction in wheezing illness.
• Spend the visit on proven steps: smoke-free homes, vaccination and early review of recurrent wheeze.
• Where a family already uses one, review whether continuing it is worth the cost.

Why it matters

It puts a commonly prescribed immune-stimulating product to a rigorous test and finds no benefit for this use.

Don't overread it

The trial tested prevention in high-risk children in the United States; it does not address other uses of bacterial lysates, such as recurrent respiratory infections.

The statistics, in plain English

A hazard ratio of 1.16 with an interval of 0.82 to 1.64 means the data are compatible with a modest benefit, no effect or a modest increase in wheezing, and the point estimate leaned slightly the wrong way. With 822 children and long follow-up, the trial was large enough to show a worthwhile benefit if one existed.

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