Effect of indoor environmental interventions in the home on asthma in children and adolescents: A systematic review.

Background: Asthma is the most frequent chronic respiratory disease in childhood. Children spend much time indoors and are therefore exposed to many indoor allergens and pollutants for several hours during day and night. Many different measures have been investigated in an attempt to reduce the different indoor asthma triggers. The objective of this review was to evaluate the effect on asthma in children and adolescents of home environmental interventions.

Methods: A systematic review was conducted by searching five electronic databases and including randomised controlled trials studying the effect of environmental interventions, not aimed at tobacco smoke and smoke alone, on childhood allergic asthma. Data were extracted using a predefined template and quality of the evidence assessed using Cochrane risk-of-bias tool and the GRADE approach.

Results: We identified 13,124 studies and included 54 of which 24 intervened on house dust mites, 3 on pet allergen, 4 on pest allergen, 17 on indoor air quality and 6 were multifaceted interventions. There was a high degree of heterogeneity, and only three studies of high quality. A significant effect was found in two high quality studies on mattress covers, four (1 high, 1 moderate, 2 very low quality) studies on nocturnal, temperature-controlled laminar airflow and low evidence for effect of multifaceted interventions. Apart from this no clear effects of other interventions were found.

Conclusion: Multifaceted interventions, nocturnal laminar air flow and mitigating HDM exposure by mite-impermeable mattress covers are promising interventions. Future studies should use relevant asthma outcome measures and a rigorous study design based on experience from former studies.