title: The relationship between combination inhaled corticosteroid and long-acting β-agonist use and severe asthma exacerbations in a diverse population.
abstract: BACKGROUND
  Safety concerns surround the use of long-acting β-agonists (LABAs) for the treatment of asthma, even in combination with inhaled corticosteroids (ICSs) and particularly in high-risk subgroups.
  
  
  OBJECTIVE
  To estimate the effect of ICS therapy and fixed-dose ICS/LABA combination therapy on severe asthma exacerbations in a racially diverse population.
  
  
  METHODS
  ICS and ICS/LABA exposure was estimated from pharmacy data for patients with asthma aged 12 to 56 years who were members of a large health maintenance organization. ICS and ICS/LABA use was estimated for each day of follow-up to create a moving window of exposure. Proportional hazard models were used to assess the relationship between ICS and ICS/LABA combination therapy and severe asthma exacerbations (ie, use of oral corticosteroids, asthma-related emergency department visit, or asthma-related hospitalization).
  
  
  RESULTS
  Among the 1828 patients who met the inclusion criteria, 37% were African American, 46% were treated with ICS therapy alone, and 54% were treated with an ICS/LABA combination. Models assessing the risk of severe asthma exacerbations among individuals using ICS treatment alone and ICS/LABA combination therapy suggested that the overall protective effect was as good or better for ICS/LABA combination therapy when compared with ICS treatment alone (hazard ratio, 0.65 vs 0.72, respectively). Analyses in several subgroups, including African American patients, showed a similar statistically significant protective association for combination therapy.
  
  
  CONCLUSIONS
  Treatment with ICS/LABA fixed-dose combination therapy appeared to perform as well as or better than ICS treatment alone in reducing severe asthma exacerbations; this included multiple high-risk subgroups.
authors.affiliation: Department of Public Health Sciences, Henry Ford Health System, Detroit, MI 48202, USA. kwells1@hfhs.org
authors.forename: Karen E
authors.initials: KE
authors.lastname: Wells
authors.forename: Edward L
authors.initials: EL
authors.lastname: Peterson
authors.forename: Brian K
authors.initials: BK
authors.lastname: Ahmedani
authors.forename: Richard K
authors.initials: RK
authors.lastname: Severson
authors.forename: Julie
authors.initials: J
authors.lastname: Gleason-Comstock
authors.forename: L Keoki
authors.initials: LK
authors.lastname: Williams
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage* / Q000009:adverse effects; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage* / Q000009:adverse effects; D000328:Adult; D001249:Asthma / Q000188:drug therapy* / Q000453:epidemiology* / Q000503:physiopathology; D002648:Child; D018450:Disease Progression; D004347:Drug Interactions; D004632:Emergency Medical Services / Q000706:statistics & numerical data; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007345:Insurance Claim Review / Q000706:statistics & numerical data; D008297:Male; D044469:Racial Groups; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones; D000318:Adrenergic beta-Agonists