Environmental Intervention Versus Standard Care to Reduce Pharmacologic Therapy for Asthma

Research question(s):

In individuals with atopic asthma who are being treated with inhaled corticosteroids with or without long acting beta agonists (1 of 6 possible steps of treatment), aggressive environmental intervention to reduce exposure to home allergens is more likely to lead to one step reduction in asthma controller therapy, improved asthma control and improved biomarkers of airway inflammation than is usual care.

Scientific abstract:

Environmental exposure to indoor allergens is a major contributor to asthma impairment and risk, particularly among asthmatic patients residing in inner cities. The investigators plan a randomized controlled trial to assess the effect of individualized, comprehensive, multifaceted indoor allergen avoidance measures on ability to step down asthma controller therapy in adults and children greater than 6 years with mild to severe persistent asthma.

Specifically,

• To determine via a randomized, controlled trial in allergen sensitized asthma patients whether environmental intervention aimed at reducing exposure to indoor allergens and irritants is more effective in reducing National Asthma Education and Prevention Program (NAEPP) step based therapy than usual care over a 48 week study period.

2a. To determine if environmental intervention leads to reduction in indoor allergen levels, allergen specific serum IgE levels, airway hyper-responsiveness, fractional excretion of nitric oxide, asthma symptom score, asthma exacerbations, treatment failures and improved lung function compared to usual care over a 48 week study period.

2b. (Exploratory): To determine if there is an association between reduction in allergen specific IgE level and reduction in NAEPP step level required for asthma control among subjects randomized to environmental intervention compared with usual care.

Inclusion criteria

• Clinical history consistent with asthma in male and female subjects ages 6 and above.
• Need for controller therapy demonstrated by current use of a stable dose (at least 4 weeks) of long term asthma controller therapy; or if not receiving long term asthma controller, symptoms consistent with persistent asthma (eg. Symptoms > 3x per week).
• Prebronchodilator FEV1 > 40% predicted at screening (V0)
• Positive skin test (defined as wheal greater than 3 mm in diameter greater than saline negative control) to protein extracts of at least one of 9 common indoor allergens including dust mites, cockroach mix, rat, mouse, Alternaria, Cladosporium, Aspergillus, cat and dog tested at Visit 0 (or positive RAST test to at least on aeroallergen if FEV1<60% at Visit 0 precluding allergen skin testing.)
• Evidence of at least one allergen in household dust which matches skin test positivity or RAST testing (overlap to be checked and recorded at V3).
• Asthma confirmed by either reversibility to 4 puffs albuterol greater than or equal to 12% in FEV1 at V0 OR PC20 FEV1 methacholine of less than or equal 16 mg/ml at or up to 30 days previous to V1.
• Sleeps overnight at same address at least 5 times per week.

Exclusion criteria

• Significant medical illness other than asthma including other chronic respiratory illness (eg emphysema, cystic fibrosis)
• Currently receiving immunotherapy or received such therapy in the past year
• Emergency Department (ED) visit for asthma or steroid taper within the past 2 weeks (may be rescreened at a future date).
• Investigational drug within the past 30 days; anti-IgE therapy within past 6 months
• Active smoker or greater than 10 pack year history of asthma
• Asthma requiring mechanical ventilation within the past 5 years
• Significant occupational exposures as determined by principal investigator.