Cat exposure and asthma outcomes in a cohort of children with asthma and allergy

Introduction The impact of current pet exposure on children with allergic asthma is not yet fully understood. This study aimed to investigate the association between cat exposure and asthma outcomes in children with established asthma and allergy. Methods A population-based cohort study using Swedish national health, sociodemographic, and quality registers was conducted. We included 30 277 children aged 4–17 years (born 2006–2020), with validated diagnoses of asthma and allergy, who had asthma care during the two years preceding exposure assessment. Cat exposure was defined as parental cat ownership recorded in the National Cat Register in 2023. Asthma outcomes, assessed during 2023–2024, included: asthma exacerbation and moderate-to-severe asthma. In a subset with available data ( n = 1428), Forced Expiratory Volume in 1 Second (FEV 1 ) and asthma control test (ACT) were evaluated. Odds ratios (ORs) were adjusted for sex, age, initial asthma severity, baseline airway allergy severity, parental asthma and allergy, population density, parental birth country, and socioeconomic status. Results Of the study population (median age: 9.5 years, 39% females), 9.4% ( n = 2,862) had cat exposure. Initial asthma severity was comparable between the cat-exposed and non-exposed groups (19.5% vs. 20.6% with moderate-to-severe asthma). Asthma exacerbation occurred in 3.3% of the cat-exposed group vs. 3.5% of the non-exposed group (adjusted OR: 1.12, 95% CI: 0.90–1.39). Moderate-to-severe asthma was observed in 9.6% vs. 10.1% (adjusted OR: 0.96, 0.84–1.10). No significant differences were found in ACT or FEV₁ z-scores. Within the cat-exposed group, no association between the number of cats, cat sex, or age and asthma outcomes was observed. Conclusion In this cohort of children with asthma and allergy, no association between cat exposure and asthma exacerbations, severity, lung function, or asthma control was observed. These findings suggest that cat exposure may not adversely affect asthma outcomes in this population.