BOSTON — Inner-city children with asthma, who are exposed to elements carried by dogs, such as bacteria, may have decreased symptoms and a reduced need for treatment, according to findings presented at the American College of Allergy, Asthma and Immunology annual meeting.
“This topic is important because the prevalence of asthma has increased in the past few decades, particularly in developed countries,” Po-Yang Tsou, MPH, MD, from the department of anesthesiology and critical care medicine at Johns Hopkins University, told Healio Family Medicine. “Accumulating evidence suggests that the microbiome in patients with asthma is different from that of healthy people, but we don't know if the change in microbiome causes development or progression of asthma.”
Tsou and colleagues performed a mediation analysis that differentiated the effect of nonallergen factors such as bacteria from the allergen’s effect to provide what Tsou called an “alternative way” to support the hypothesis that the microbiome affects allergic diseases.
They recruited 180 inner-city children (mean age, 9.6) with asthma to undergo allergy testing and report clinical asthma outcomes at baseline, 3 months, 6 months and 9 months. Simultaneous home dust sampling and home inspections occurred at the participants’ homes to quantify allergen exposure and determine animal exposures.
After adjusting for allergen exposures, researchers found that among those sensitized to dog allergen, exposure to nonallergen dog-associated factors was associated with decreased morning inhaler use (mediator-adjusted OR = 0.33; 95% CI, 0.11-0.94) and decreased nighttime asthma symptoms (mediator-adjusted OR = 0.31; 95% CI, 0.13-0.74).
Conversely, dog allergen exposure was associated with increased morning inhaler use (OR = 6.92; 95% CI, 1.26-37.98) and nighttime asthma symptoms (OR = 5.48; 95% CI, 1.86-16.13). In addition, the protective effect was not observed in children sensitized and exposed to cats, mice or cockroaches, according to researchers.
Tsou told Healio Family Medicine that although the findings are “exciting,” he stressed that it is premature for primary care physicians to change how they treat or advise their patients.
“There is no solid evidence on the protective effect of nonallergen factors despite promising preliminary results. If children have asthma and are allergic to dogs, PCPs should not change asthma treatments,” he said. “Instead, PCPs should work with patients and their parents to reduce allergen exposure to have better control over the patient’s asthma.” – by Janel Miller
Tsou P, et al. Poster 238. Presented at: the American College of Allergy, Asthma and Immunology 75th Annual Scientific Meeting; Oct. 26-30, 2017; Boston.
Tsou reports no relevant financial disclosures. Healio Family Medicine was unable to determine the other authors’ relevant financial disclosures prior to publication.