Table 1. Diagnostic criteria and information on pet exposure in the Cross-Sectional Cohort and Birth Cohort.
| Criterion | Cross-Sectional Cohort | Birth Cohort |
|---|---|---|
| Diagnosis of asthma | “Asthma ever” diagnosed if there was a positive response to: “Has your child had asthma or asthmatic bronchitis”? “Current asthma” diagnosed if there was a positive response to “Has your child had asthma or asthmatic bronchitis in the previous year”? |
Asthma diagnosed at age 8–9 years if the child in the last 12 months had symptoms of wheeze/heavy breathing together with: FEV1 reversibility >12%, or bronchial hyperresponsiveness to methacholine (PD20 <0.6 mg), or ongoing controller medication with inhaled corticosteroids or leukotriene antagonist |
| Diagnosis of ARC | ARC diagnosed if there was a positive response to: “Has your child had allergic rhinitis or allergic conjunctivitis”? “Current ARC” diagnosed if there was a positive response to: “Has your child had allergic rhinitis or allergic conjunctivitis in the previous year”? |
ARC diagnosed at age 8–9 years if the child in the last 12 months had eye or nose symptoms suggestive of allergic disease together with a positive skin-prick test or specific IgE to the relevant allergen |
| Diagnosis of eczema | “Eczema ever” diagnosed if there was a positive response to: “Did your child ever have eczema”? “Current eczema” diagnosed if there was a positive response to: “Did your child have eczema in the previous year”? |
Eczema diagnosed at age 8–9 years if the child in the last 12 months had a skin condition fulfilling Williams criteria [16], or an itching dermatitis that had been chronic or relapsing for ≥6 months |
| Diagnosis of allergy | “Allergy ever” and “allergy last year” included any of asthma, ARC, or eczema ever or last year, respectively | “Allergy last year” included any of asthma, ARC, or eczema |
| Cats and dogs in household | Number of cats and dogs in the household during the first year of life | Data on number of cats and dogs was obtained from the 6-month telephone interview |
ARC, allergic rhinoconjunctivitis; FEV1, forced expiratory volume in 1 s; Ig, immunoglobulin; PD20: provocative dose inducing a fall of ≥20% in FEV1.