The Asthma Family Tree: Evaluating Associations Between Childhood, Parental, and Grandparental Asthma in Seven Chinese Cities

Abstract

Objective: To evaluate the associations between childhood, parental, and grandparental asthma. Methods: We studied 59,484 children randomly selected from 94 kindergartens, elementary, and middle schools in seven Chinese cities from 2012 to 2013, using a cross-sectional survey-based study design. Information on their and their family members' (parents, paternal grandparents, and maternal grandparents) asthma status were reported by children's parents or guardians. Mixed effects logistic regressions were used to assess hereditary patterns of asthma and mediation analysis was performed to estimate the potential mediation effect of parents on the association between grandparental asthma and childhood asthma. Results: The magnitude of ORs for childhood asthma increased as the number of family members affected by asthma increased. Among children who had one family member with asthma, childhood asthma was associated with asthma in maternal grandmothers (OR: 2.08, 95% CI: 1.67-2.59), maternal grandfathers (OR: 2.08, 95% CI: 1.71-2.53), paternal grandmothers (OR: 2.40, 95% CI: 1.93-2.99), and paternal grandfathers (OR: 2.59, 95% CI: 2.14-3.13). Among children who had two family members with asthma, the highest asthma risk was found when both parents had asthma (OR: 15.92, 95% CI: 4.66-54.45). Parents had a small proportion of mediation effect (9-12%) on the association between grandparental asthma and childhood asthma. Conclusions: Grandparents with asthma were associated with childhood asthma and parents with asthma partially mediated the association.

Keywords: childhood asthma; cross-sectional study; family history; hereditary patterns; mediation effect.

Figure 1

Adjusted ORs and 95%CIs for childhood asthma by the number of family members affected by asthma compared to those without any family member affected. Adjusted for passive smoke exposure, home coal use, pet kept and PM_2.5 exposure. Asthma cases: 3,529 cases with 1 family member affected, 279 cases with 2 family members affected, and 35 cases with ≥3 family members affected.

Figure 2

Adjusted ORs and 95%CIs for asthma among children with one family member affected by asthma compared to those without any family member affected. Adjusted for passive smoke exposure, home coal use, pet kept and PM_2.5 exposure. Asthma cases: 75 cases with affected fathers, 67 cases with affected mothers, 132 cases with affected paternal grandfathers, 97 cases with affected maternal grandfathers, 119 cases with affected paternal grandmothers, and 95 cases with maternal grandmothers.

Figure 3

Adjusted ORs and 95%CIs for asthma among children with two family members affected by asthma compared to those without any family member affected. Adjusted for passive smoke exposure, home coal use, pet kept and PM_2.5 exposure. Asthma cases: 5 cases with affected parents, 10 cases with paternal grandparents affected, 7 cases with maternal grandparents affected, 16 cases with father and paternal grandfather affected, 5 cases with father and paternal grandmother affected, 3 cases with mother and maternal grandfather affected, and 8 cases with mother and maternal grandmother affected.