Asthma in Siblings and Risk for Childhood Asthma
Saturday, March 3, 2018
South Hall A2 (Convention Center)
David L. Peloza, MD, Michael D. Evans, MS, James E. Gern, MD FAAAAI, Robert F. Lemanske, MD FAAAAI, Daniel J. Jackson, MD FAAAAI

RATIONALE: Sibling asthma as a risk factor for childhood asthma inception has not been extensively evaluated. We hypothesized that having an older sibling with asthma would increase asthma risk.

METHODS: 289 newborns at high-risk based upon parental histories of asthma and/or allergy were enrolled in the Childhood Origins of Asthma (COAST). Asthma was diagnosed at 6, 8, 11 and 13 years based on physician diagnosis of asthma, patterns of medication use and symptoms. The relationship between older sibling and parental asthma and subsequent asthma was analyzed using logistic regression.

RESULTS: Rates of asthma according to family history at ages 6-13 years were 19-23%, 27-31%, 36-40%, and 40-49% for children without family history of asthma, parental asthma, sibling asthma, or both parental and sibling asthma, respectively. Asthma in older siblings was associated with increased odds of asthma at ages 6, 8, 11, and 13 years (OR 1.95, 95%CI 1.09-3.48, p=0.03; OR 2.15 95%CI 1.19-3.87, p=0.01; OR 2.06, 95%CI 1.11-3.84, p=0.02; OR 1.88 95%CI 1.00-3.56, p=0.05, respectively). Parental asthma was not associated with a significant increase in risk.

CONCLUSIONS: In our high-risk birth cohort study, older sibling asthma was associated with an increased risk of asthma. Both genetic and environmental factors shared by siblings are likely to contribute to this increased asthma risk. Our inclusion criteria required at least one parent to have respiratory allergies, which may explain why parental asthma was not a significant risk factor.