title: Characterization of the duration from onset of asthma symptoms to asthma disease.
abstract: BACKGROUND
  Little is known about factors associated with progression of childhood asthma from onset of symptoms to index date determined by medical records.
  
  
  OBJECTIVE
  To determine the duration between the onset of asthma symptoms to index date of asthma (ie, time when one met the criteria for asthma) and associated factors.
  
  
  METHODS
  Study participants came from a sample of 839 healthy children, aged 5 to 12 years, who had participated in a previous study. Comprehensive medical record reviews were conducted to determine first documentation of asthma symptoms and index date of asthma. Factors were evaluated for an association with the duration from onset of asthma symptoms to index date of asthma.
  
  
  RESULTS
  Of the study sample, 222 children met the criteria for asthma and had an available onset date of asthma symptoms. The median ages at onset of asthma symptoms and the index date were 5.6 and 7.6 years, respectively. The median duration between onset of asthma symptoms and index date was 2.9 months, and the mean was 17.2 months. There was a tendency for patients with a pet at home (P = .047), exercise-induced symptoms (P = .04), younger age at symptom onset (P = .05), and more severe asthma (P = .05) to have a shorter duration from onset of symptoms to index date.
  
  
  CONCLUSIONS
  The duration from onset of asthma symptoms to index date of asthma varies significantly depending on host and environmental factors. It does not necessarily correlate with commonly recognized risk factors for incidence or severity of asthma.
authors.affiliation: Mayo Medical School, Rochester, Minnesota 55905, USA.
authors.forename: Molly
authors.initials: M
authors.lastname: Martyn
authors.forename: Amy L
authors.initials: AL
authors.lastname: Weaver
authors.forename: Robert M
authors.initials: RM
authors.lastname: Jacobson
authors.forename: Young J
authors.initials: YJ
authors.lastname: Juhn
mesh_terms: D000293:Adolescent; D000367:Age Factors; D017668:Age of Onset; D000818:Animals; D000829:Animals, Domestic; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology; D001250:Asthma, Exercise-Induced / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008910:Minnesota / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors