Relationship between asthma severity and age at onset in Japanese adults]

The relationship between age at onset of adult asthma and asthma severity has not been comprehensively investigated.A total of 4161 patients with asthma (1578 men) aged 16 years or older were classified into 4 groups according to their age at asthma onset: group A (16-19 years), group B (20-39 years), group C (40-59 years), and group D (>60 years). We examined the relationship between the age at onset and severity of asthma among the 4 groups and analyzed factors associated with asthma severity.The severity of asthma rose with increasing age at onset, and vice-versa. Factors associated with severity of adult onset asthma were analyzed using multiple regression analysis. Asthma duration, total serum IgE level, smoking status, and age at onset were strongly associated with asthma severity. Age at onset was independently associated with the severity of adult-onset asthma.Our findings indicate that asthma severity is positively associated with age at onset in patients with adult-onset asthma.