Cat ownership in early life and sensitization to cat at age 5 years: A prospective study

Abstract

Rationale We investigated the effect of cat ownership and exposure to cat allergen on sensitization to cat at age 5 years. Methods Within the context of a prospective birth cohort (Manchester Asthma and Allergy Study), 468 children had specific IgE to cat measured at age 5 years. Sensitization was defined as cat specific IgE greater than 0.2 kU/l. Pet ownership was recorded during pregnancy, at age 3 and at age 5. Fel d 1 and endotoxin levels were measured in dust collected from the living room floor at age 5. Children who had never owned a pet (cat or dog) were used as the reference (n=255). Chi square tests and logistic regression were used in the analysis. Where stated, odds ratios are adjusted for gender, parental atopy, child care arrangements, maternal age and endotoxin exposure (aOR). Results Of children who had never owned a pet, 6.7% were sensitized to cat. Cat ownership was a significant associate of cat sensitization, whether analyzed as cat ever (13.3%, p=0.027), cat always (17.1%, p=0.005), cat in early life (14.2%, p=0.018), cat at age 3 years (14.9%, p=0.015) or cat at age 5 years (16%, p=0.006). These relationships remained in the multivariate analysis (e.g. for cat age 5, aOR 2.54, 95% CI 1.1-5.6, p=0.02). Increasing levels of Fel d 1 in the living room carpet were significantly associated with sensitization to cat (aOR 1.16, 95% CI 1.02-1.32, p=0.024). Conclusions Cat ownership and exposure to cat allergen are risk factors for sensitization to cat at age 5 years.