No abstract

Background: We previously reported an increased prevalence of asthma among patients who had lived in temporary housing after the 2011 Great East Japan Earthquake. We investigated the prognosis of asthma in former residents of temporary housing after allergen avoidance.Methods: Asthma was diagnosed in adults ≥ 15 years from 2014 to 2019 who had lived in temporary housing in Ishinomaki City for at least 1 year. The disease prognosis after the intervention of allergen avoidance in cases that were followed for more than 3 years during the 6-year study period was analyzed. We measured the Dermatophagoides farinae -specific immunoglobulin E (IgE) levels in serum, and the amount of Dermatophagoides group 1 (Der 1) antigen on their futons or mattresses. We instructed residents in an allergen avoidance strategy that included 32 tasks, including using microfiber bedding covers. Results: Of the 202 examinees who were followed for at least 3 years during the 6-year study period, 72(35.6%) were asthmatic during at least one examination. Of these 72 asthmatics, 55(76.4%) developed the disease after the earthquake, and more than half of the cases that we diagnosed at the examination were mild intermittent asthma. After the allergen-avoidance intervention, both the Der 1 level on the futons or mattresses of residents who were diagnosed with asthma but who were nonasthmatic at the final screening and their serum Der f-specific IgE levels significantly decreased (P < 0.01) at the final examination.Conclusion: Antigen avoidance ameliorated mild asthma that was prevalent among residents of temporary housing after the earthquake.