Are allergen avoidance measures worth the trouble in asthma?

Published Online: March 26, 2016

Environmental exposures to indoor allergens are major contributors to asthma symptoms, particularly in inner cities. National asthma management guidelines emphasize the need for individualized environmental control measures in the treatment of asthma. However, the effectiveness of allergen reduction in the home has demonstrated mixed results regarding asthma outcomes, partly due to lack of standardization in asthma medications before and during interventions. In The Journal of Allergy and Clinical Immunology: In Practice, DiMango and colleagues report the results of a study testing the effectiveness of allergen avoidance as an adjunct to asthma medication use in a group of adults and children residing in New York City.

Strategies to reduce household allergen levels were based on individual allergic sensitivity and household exposure. Skin testing or Immunocap was used to measure allergic sensitization. Household exposure to specific allergens was measured in dust samples collected from the participant’s bedroom and kitchen. One hundred and twenty five participants were randomized to receive an intervention targeted to allergen reduction and 122 participants were randomized to receive usual care, which include a sham home visit. All participants had asthma controller medications optimized during a run-in period utilizing National Asthma Education and Prevention Program (NAEPP) Guidelines and demonstrated well controlled asthma defined as Asthma Control Test score of > 19. Participants in the intervention arm received an individualized home-based program by intervention counselors utilizing standardized modules targeting furry pets, cockroach, dust mite, rodents and mold. Participants in the control arm received similarly timed home visits targeted to issues not related to asthma, such as safety of window guards. During the treatment reduction phase, asthma controller therapy was adjusted every 8 weeks by blinded study physicians utilizing a standardized algorithm based on NAEPP Guidelines.

Subjects in both treatment groups had demonstrated reduction of allergen levels in dust samples collected from the home. Both groups reduced guideline based asthma therapy, with no significant difference between groups. The intervention group reduced therapy from a mean step of 4.4 to 3.5 (Range 0-6) while the participants with no directed allergen avoidance reduced medication use from step 4.4 to 3.4 (p=0.76). Secondary outcomes such as pulmonary function, asthma symptom days, asthma quality of life scores and a composite asthma symptom index did not differ between groups.

Exposure to indoor allergens among sensitized asthmatic patients has been associated with worse asthma severity and increased healthcare utilization. The study by DiMango, etal analyzed allergen reduction measures as a treatment for asthma, but did not demonstrate ability of such measures to improve outcomes or reduce need for asthma controller therapy in those receiving guideline-based therapy. Allergen reduction measures effectively reduced levels of all measured household allergens, but did not lead to incremental reduction in asthma step-level care compared with a control group. The control group also demonstrated reduction in some household allergen levels. This study highlights the need for further studies to inform current guidelines for allergen avoidance in asthmatic individuals.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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