title: Ten-year trends in direct costs of asthma: a population-based study.
abstract: BACKGROUND
  There is little information on recent trends in the economic burden of asthma. Our objective was to estimate the excess costs of asthma and their trend in British Columbia, Canada, from 2002 to 2011.
  
  
  METHODS
  A retrospective cohort of individuals aged 5-55 years was constructed from the provincial administrative health databases, consisting of patients with physician-diagnosed asthma and a propensity-score-matched comparison sample from the general population. Total direct medical costs were calculated as the sum of hospitalizations, outpatient visits and medication costs, adjusted to 2012 Canadian dollars ($). Excess costs were defined as the difference in costs between the asthma and comparison groups.
  
  
  RESULTS
  A total of 341 457 individuals (mean age at entry 27.3, 54.1% female) were equally divided into the asthma and comparison groups. Excess costs in patients with asthma were $1028.0 (95% CI $982.7-$1073.4) per patient-year (PY). Medications contributed to the greatest share of excess costs ($471.7/PY), whereas hospitalization and outpatient costs were, respectively, $272.2/PY and $284.1/PY. Only $192.9/PY was attributable to asthma itself. There was a 2.9%/year increase in excess costs (P < 0.001), a combination of asthma-attributable costs declining by 0.8%/year while nonasthma excess costs increasing by 3.8%/year. The most dramatic trend was observed in asthma-related outpatient costs, which decreased by %6.6/year.
  
  
  CONCLUSIONS
  A significant share of excess costs in asthma is not attributable to the disease itself. The pattern of costs changed significantly during the study period. The burden of comorbid conditions should be considered in developing evidence-based policies for management of patients with asthma.
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada.|Centre for Clinical Epidemiology and Evaluation, The University of British Columbia, Vancouver, BC, Canada.|Department of Medicine, Institute for Heart and Lung Health, The University of British Columbia, Vancouver, BC, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Tavakoli
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada.|Centre for Clinical Epidemiology and Evaluation, The University of British Columbia, Vancouver, BC, Canada.
authors.forename: J M
authors.initials: JM
authors.lastname: FitzGerald
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada.
authors.forename: W
authors.initials: W
authors.lastname: Chen
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Lynd
authors.affiliation: The Institute for Clinical Evaluative Sciences, Toronto, ON, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Kendzerska
authors.affiliation: The Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Aaron
authors.affiliation: The Hospital for Sick Children, Toronto, ON, Canada.|Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Gershon
authors.affiliation: School of Pharmacy, Memorial University of Newfoundland, St. John's, NF, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Marra
authors.affiliation: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada.|Centre for Clinical Epidemiology and Evaluation, The University of British Columbia, Vancouver, BC, Canada.|Department of Medicine, Institute for Heart and Lung Health, The University of British Columbia, Vancouver, BC, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Sadatsafavi
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D016527:Drug Costs; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data* / Q000639:trends*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012959:Socioeconomic Factors; D055815:Young Adult
keywords: asthma; burden of diseases; cohort studies; costs; observational studies