Atopic status
This was assessed by skin prick test (SPT) using a panel of 20 common inhalant allergens, including pollens, house dust mites, molds, and animal dander, and 27 common food allergens including animal, fruit, and vegetable allergens (ALK, Madrid, Spain). Histamine hydrochloride (10 mg/ml) and phenolated glycerol saline were used as positive and negative controls, respectively. Patients were requested to stop taking any antihistamine medication at least 8 days before undergoing SPT. A positive SPT response was defined as a wheal diameter of 3 mm or larger to at least one of these allergens; patients developing such a wheal were considered atopic.