Classification of etiology by age groups.

*expressed as percentage of patients within age group.
†HSV was diagnosed with a positive polymerase chain reaction test.
‡Psoriasis was diagnosed based on a clinical diagnosis of IU and dermatologic manifestations diagnosed as psoriasis by a dermatologist.
Abbreviations: TB, tuberculosis; HSV, Herpes simplex virus; HIV, human immunodeficiency virus; MS, multiple sclerosis; AS, ankylosing spondylitis; JIA, juvenile idiopathic arthritis.