D2.160 - Household Overcrowding and Number of Siblings as Risk Factors for Uncontrolled Asthma in Inner-City Children

Substandard housing conditions are well-recognized contributor to asthma morbidity in inner-city populations, though specific mechanisms remain incompletely understood. Household dampness is frequently cited as a risk factor; however, its clinical impact may be confounded by co-exposures to multiple allergens, particularly molds. Similarly, the independent contribution of household crowding—specifically, number of siblings has received limited attention. The possible mechanism here may be the resuspension of the allergens in the air. We examined these environmental factors in a group of inner-city children living in İstanbul, Türkiye.

This cross-sectional study enrolled 246 inner-city children (mean age 9.1±3.1 years) with physician-diagnosed asthma. The children included in the study were divided into two groups: the first group consisted of those who were monosensitized to house dust mites (HDM), whereas the second group consisted of children with non-atopic asthma. All participants subsequently underwent standardized skin prick testing for HDM, molds, cat, dog, and common pollens. Environmental exposures, including the visible household dampness and also number of siblings, were then assessed via standardized questionnaires. Finally, multivariate logistic regression identified predictors of uncontrolled asthma (ACT/c-ACT), adjusting for age, sex, treatment adherence, and rhinitis severity.

Among participants, HDM monosensitization was identified in 176 children (71.5%), while 70 were non-atopic. Analysis revealed phenotype-specific environmental risk patterns (interaction p<0.05). Notably, among HDM-monosensitized children, each additional sibling substantially increased the odds of poor control (adjusted OR: 2.02; 95% CI: 1.25–3.26; p=0.004), and household dampness conferred additional independent risk (adjusted OR: 2.73; 95% CI: 1.70–4.38; p<0.001).

Surprisingly, neither dampness nor the number of siblings predicted asthma control in the group of non-atopic children. Here, the severity of rhinitis was identified as the significant factor leading to poor asthma control (adjusted OR: 4.11; 95% CI: 1.55–10.87; p=0.004).

In our group of asthmatic inner-city children, household dampness remained as a strong risk factor among HDM-monosensitized patients, suggesting that humidity-related asthma morbidity operates primarily through dust mite proliferation rather than direct fungal allergy. The negative impact of the number of siblings on asthma control in these children suggests that increased indoor activity and the resulting resuspension of allergens in the air may play a role. Our findings suggest that aggressive indoor environmental avoidance measures are necessary in children susceptible to house dust mites, while upper respiratory tract management may be beneficial in non-atopic patients.