title: [The relationship between the duration and severity of asthma].
abstract: BACKGROUND
  The relationship between the duration and severity of asthma has not been comprehensively investigated.
  
  
  METHODS
  We examined the relationship between duration of asthma and asthma severity among 4776 patients with asthma: 608 with childhood-onset persistent asthma (12.7%), 187 with adolescent-onset asthma (3.9%), and 3981 with adult-onset asthma (83.4%). The assessment of asthma severity was based on the Japanese Guidelines for The Diagnosis and Treatment of Allergic Diseases, 2007 (JGL 2007).
  
  
  RESULTS
  Asthma severity was assessed at 2 years, 3 to 10 years. 11 to 20 years, and 21 years or longer after disease onset. Disease severity significantly increased with greater asthma duration (p<0.001). This relationship was not affected by serum total IgE concentration (<300 IU/ml vs > or = 300 IU/ml), smoking status, house dust mite-specific serum IgE antibody level, or gender.
  
  
  CONCLUSIONS
  Our findings suggest that bronchial asthma is a disease that worsens over time.
authors.affiliation: Niigata Allergic Disease Research Institute/Tsukioka Clinic for Internal Medicine.
authors.forename: Kazuharu
authors.initials: K
authors.lastname: Tsukioka
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Toyabe
authors.forename: Kouhei
authors.initials: K
authors.lastname: Akazawa
mesh_terms: D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D013997:Time Factors