Factors associated to the development of atopy in young Spanish adults

BACKGROUND: To determine the risk factors for the development of atopy in S panish young adults. SUBJETS AND METHODS: Case-control study over prevalent cases. Carried out i n general population between the ages of 20 to 44 years old. Spanish partic ipants of the ECRHS, a ramdom representative sample of Spanish young adults (n = 16,884), and a 20% randomised subsample made by those who answered to a short respiratory questionnaire and had atopy assessed, was studied. Ato py was defined as having serum specific IgE positivity to the following aer oallergnes: cat dander, Cladosporium herbarum, Dermatophagoides pteronyssin us, Parietaria judaica and Phleum pratense. RESULTS: Several factors had a statistically significant effect. In additio n to male gender and lower age, maternal allergy (OR = 1.63; 95% CI = 1.11- 2.40), having allergic siblings (OR = 1.40; 95% CI = 1.06-1.90) and a highe r educational level (OR = 1.69; 95% CI = 1.22-2.34) were associated with th e presence of high levels of specific IgE in our sample. Moreover, having h ad older siblings, especially older brothers appears to be a protective fac tor to the development of atopy but not in a statistically significant way, while having had pet birds during childhood appears to enhance the risk. CONCLUSIONS: In addition to the familial variables that indicates both envi ronmental and genetic factors, educational level seems to have low degree o f association with atopy; this feature shows that variables related with li fe style are involved in atopy development.