Hygiene factors associated with childhood food allergy and asthma

Background: Childhood food allergy and asthma rates are increasing. The hygiene hypothesis has been proposed as an explanation for the increased incidence of allergic disease. Objective: To describe the association of childhood food allergy and asthma with hygiene factors, such as the number of siblings, antibiotic use, infection history, pet exposure, child care exposure, and maternal-child factors. Methods: Children ages 0-21 years old (N = 1359) were recruited for a cross-sectional family-based study, including children with food allergy and children without food allergy, and their siblings. We assessed the associations between childhood food allergy and asthma with hygiene factors. Results: Of the 1359 children, 832 (61.2%) had food allergy, and 406 (30%) had asthma. In the adjusted analysis, the prevalence of food allergy was increased if there was a history of skin infection (prevalence ratio [RRR] 1.12 [95% confidence interval {CI}, 1.01-1.24]) or eczema (RRR 1.89 [95% CI, 1.70-2.10]). The prevalence of asthma was increased with a history of respiratory syncytial virus infection (RRR 1.60 [95% CI, 1.34-1.90]) or eczema (RRR 1.54 [95% CI, 1.27-1.86]). A greater number of siblings were associated with a decreased prevalence of food allergy (RRR 0.79 [95% CI, 0.75-0.84]) and asthma (RRR 0.82 [95% CI, 0.74-0.91]). Conclusion: Our findings supported the accumulating evidence of an association between skin infections and eczema with food allergy. Because these results could be subject to recall bias, additional prospective studies are needed to substantiate these findings.