Parent-determined oral montelukast therapy for preschool wheeze with stratification for arachidonate 5-lipoxygenase (ALOX5) promoter genotype: a multicentre, randomised, placebo-controlled trial

Nwokoro, Chinedu, Pandya, Hitesh, Turner, Stephen, Eldridge, Sandra, Griffiths, Christopher J., Vulliamy, Tom, Price, David, Sanak, Marek, Holloway, John W., Brugha, Rossa, Koh, Lee, Dickson, Iain, Rutterford, Clare and Grigg, Jonathan (2015) Parent-determined oral montelukast therapy for preschool wheeze with stratification for arachidonate 5-lipoxygenase (ALOX5) promoter genotype: a multicentre, randomised, placebo-controlled trial. Efficacy and Mechanism Evaluation, 2 (6), 1-126. (doi:10.3310/eme02060). (PMID:26632627)

Abstract

Background
The clinical effectiveness of intermittent montelukast for wheeze in young children is unclear. Previous work has been equivocal. Variation in copy numbers of the specificity protein 1-binding motif in the arachidonate 5-lipoxygenase (ALOX5) gene promoter; where the wild type has five copies per allele, denoted here as 5/5, but variant genotypes may have 1–8 copies on each allele, denoted as x/x or 5/x, influences montelukast efficacy in asthmatic adults. This polymorphism may identify a responsive subgroup within this population.

Objectives
To assess the clinical effectiveness of montelukast in preschool wheezing children. To explore the effect of the ALOX5 promoter genotype on this effect.

Design
A multicentre, parallel-group, double-blind, randomised, placebo-controlled trial.

Setting
Twenty-one primary care sites and 41 secondary care sites in England and Scotland.

Participants
Children aged 10 months to 5 years with two or more wheeze episodes, one within the last 3 months, stratified by ALOX5 promoter genotype, either 5/5 or [5/x?+?x/x]. Children with other respiratory vulnerabilities were excluded.

Intervention
Parent-initiated 4 mg oral granules of montelukast or identical placebo administered once daily for 10 days from the onset of every cold or wheeze episode over 12 months.

Main outcome measure
Need for unscheduled medical attendance for wheezing.

Randomisation
Children were stratified by ALOX5 promoter genotype, either 5/5 or [5/x?+?x/x], where x???5. Children in each stratum were independently randomised to receive montelukast or placebo in a 1?:?1 ratio via a permuted block schedule (size 10). Clinical investigators and parents were blinded to treatment group and genotype stratum.

Methods
Genotype was identified by analysis of salivary deoxyribonucleic acid. Analysis was by intention to treat. Primary outcome data came from treatment diaries, scheduled telephone calls and caregiver records.

Results
A total of 1358 children were randomised to receive montelukast (n?=?669) or placebo (n?=?677). Consent was withdrawn for 12 (1%) children. Primary outcome data were available for 1308 (96%) children. There was no difference in unscheduled medical attendances for wheezing episodes between children in the montelukast and placebo groups {mean 2.0 [standard deviation (SD) 2.6] vs. mean 2.3 (SD 2.7) unscheduled medical attendances; incidence rate ratio (IRR) 0.88, 95% confidence interval (CI) 0.77 to 1.01; p?=?0.06}. Compared with placebo, unscheduled medical attendances for wheezing episodes were reduced in children given montelukast in the 5/5 stratum [mean 2.0 (SD 2.7) vs. mean 2.4 (SD 3.0) unscheduled medical attendances; IRR 0.80, 95% CI 0.68 to 0.95; p?=?0.01], but not in those in the [5/x?+?x/x] stratum [mean 2.0 (SD 2.5) vs. mean 2.0 (SD 2.3) unscheduled medical attendances; IRR 1.03, 95% CI 0.83 to 1.29; p?=?0.79, p-interaction?=?0.08]. We recorded one serious adverse event: a skin reaction in a child allocated to placebo.

Interpretation
There is no clear benefit of intermittent montelukast in young children with wheeze. However, the 5/5 ALOX5 promoter genotype might identify a montelukast-responsive subgroup.

Limitations
The study lacks power to confirm the validity of the suggested genotype stratum effect. Additionally, the effect is contrary to that hypothesised and is not supported by urinary data. We could not robustly measure treatment compliance.

Future work
Future work should test the stratum effect with a repeat trial in the apparently more responsive (5/5) stratum only.

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Contributors

Author: John W. Holloway

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