Questionnaire data
The questions were excerpted from the International Study of Asthma and Allergies in Childhood (ISAAC) protocol. Demographic information, environmental factors, confounding factors, and the prevalence of diagnosis and symptoms of AR were evaluated by a questionnaire. The presence of AR was determined by answers to the following questions in the questionnaire: “has your child ever been diagnosed with AR by a physician?” and “has your child ever had any symptoms of sneezing, runny nose, or stuffy nose in the last 12 months without a cold or flu?” Antibiotic use during infancy, cesarian section delivery, breast feeding, and having older siblings were selected as environmental factors related to the risk of current AR.