Objective: Among children sensitised to cat dander, the impact of indoor exposure on nasal symptoms, asthma prevalence, and control remains unclear. In regions with many free-roaming cats, distinguishing the clinical effects of indoor versus outdoor exposure is particularly challenging. This study aimed to compare direct ownership with environmental exposure in respiratory allergies and evaluate the independent effects of indoor contact.
Materials and Methods: Between October 2024 and June 2025, children aged 6–18 years who presented with allergic rhinitis and had cat-specific sensitisation confirmed by skin prick testing (wheal ≥3 mm) or serum-specific IgE (≥0.35 kU/L) were retrospectively evaluated. Participants were classified as `indoor exposure` (household cat) or `outdoor exposure` (no household cat, outdoor contact). TNSS, physician-diagnosed asthma, c-ACT, pulmonary function, and laboratory findings were compared between groups. Potential confounders, including age, sex, and polysensitisation, were adjusted for using multivariable regression.
Results: A total of 97 children (median age: 12 years; 54% male) were included. The indoor exposure group had higher TNSS values (median: 8 vs. 7; p = 0.02), a greater prevalence of asthma (71% vs. 48%; OR = 3.30, 95% CI: 1.17–9.30, p = 0.024), and lower c-ACT/ ACT scores (median: 20 vs. 22; β = –0.376; B = –3.285, 95% CI: –5.806 to –0.765, p = 0.012) compared to the outdoor exposure group. In multivariable analyses, persistent rhinitis phenotype and moderate-to-severe rhinitis severity were the main determinants of TNSS. In contrast, indoor exposure was the primary factor associated with asthma and poorer asthma control.
Conclusion: Indoor cat exposure is an independent risk factor for asthma development and poor symptom control in children with cat dander allergy. TNSS is primarily associated with the rhinitis phenotype and disease severity. In managing children with cat allergy, not only pet ownership but also environmental exposure should be clinically considered when evaluating disease control.