108 The Relationship of Pets, Vitamin D and IGE Concentrations to Upper Respiratory Infections in the First Year of Life

BACKGROUND: The childhood origins of asthma are highly complex but viral respiratory infections during the first year of life may be associated with wheezing and later asthma risk. Recent studies have shown that both exposure to household pets and higher serum vitamin D concentrations may reduce wheezing illness in children. METHODS: To investigate potential relationships between household pet exposure, cord blood (CB) vitamin D and IgE concentrations and the number of upper respiratory infections (URIs) in the first year of life, we analyzed information from a geographically-based, prospective, non-high-risk, birth cohort. Household pets were assessed during pregnancy and medical records were abstracted for doctor visits of URIs. Because of large differences in vitamin D concentrations between Blacks and Whites racial stratification was done for some analyses. RESULTS: The cohort consisted of 1055 children of whom 62.4% were Black and 49.4% were female. When all children were considered, a one natural log unit increase in CB vitamin D concentration was associated with a greater risk of a URI visit (RR = 1.27, 95% CI, 1.01-1.59, P = 0.037) which remained after adjusting for the season of birth (RR = 1.28, P = 0.033). Individually adjusting for the number of children in the family, CB IgE, child gender, family or maternal smoking and race did not substantially change the association of vitamin D to URIs (all RR's were 1.25-1.27), although the risks only remained statistically significant with CB IgE (P = 0.035) and gender (P = 0.043). When models stratified by race including pets, dogs only, or cats only, and CB IgE were fitted with the other variables, the relationship between CB vitamin D disappeared for whites but did not change in magnitude for blacks (RR = 1.31; 95% CI, 0.89-1.92; P = 0.165). Among Whites the only variable associated with URIs was a relationship with female gender (RR = 0.62, 95% CI, 0.41-0.94; P = 0.025) with being in daycare approaching significance (RR = 1.72, 95% CI, 0.94-3.14; P = 0.08). CONCLUSIONS: In a large, prospective, non-high-risk birth cohort higher, CB vitamin D concentration, after adjusting for other potential confounding variables, was not associated with a decreased risk of physician diagnosed URIs in the first year of life.