Table 1. Confounding Factors for Estimating the Propensity Score

Variable	Variable Definition
District	Seoul, Metropolitan City, City/Province
Age	Age
Gender	Male, Female
Insurance Type	Health Insurance, Medical Benefits
Comorbidity	CCI(Charlson Comorbidity Index)11)
History of Allergic Rhinitis	Visit days of Allergic Rhinitis during the past 3 Months as a Main Disease
Inpatient History of Allergic Rhinitis	Yes, No