title: Measuring exacerbations in obstructive lung disease.
abstract: OBJECTIVE
  Using hospitalization always has been seen as a solid measurement for exacerbation in pharmacoepidemiology, but might lead to an underestimation of disease exacerbation because of a trend towards outpatient care. The aim of this study was to quantify the incidence of different exacerbation markers in obstructive lung disease and to identify predictors for these exacerbation markers.
  
  
  METHODS
  We conducted a cohort study using the PHARMO record linkage system, including demographic details and complete medication histories of more than two million community-dwelling residents in the Netherlands from 1985 onwards. Eligible patients were adult users of inhaled corticosteroids (ICS). Outcome parameters were hospitalization and short courses of systemic corticosteroids. Patients were allowed to have multiple exacerbations during follow-up.
  
  
  RESULTS
  We identified 5327 patients. During follow-up, 8635 exacerbations occurred in 2332 patients with a trend in time towards treating exacerbations out of the hospital (p-value 0.003). Of all patients with exacerbations, 73% was not hospitalized during follow-up. Exacerbations were associated with high-dose ICS use (adjusted RR 1.4; 95% CI 1.2-1.7) and chronic systemic corticosteroid use (adjusted RR 1.9; 95%CI 1.6-2.2).
  
  
  CONCLUSIONS
  Using hospitalization only as exacerbation marker leads to underestimating the exacerbation rate, because of exacerbation treatment out of the hospital. Patients with obstructive lung disease using chronic systemic corticosteroids or high-dose ICS use are more prone to exacerbations. This implies that these patients should be monitored carefully to prevent recurrent exacerbations which are detrimental for their prognosis and quality of life.
authors.affiliation: Division of Pharmacoepidemiology and Pharmacotherapy, Faculty of Science, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands.
authors.forename: Karin J
authors.initials: KJ
authors.lastname: Velthove
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Souverein
authors.forename: Wouter W
authors.initials: WW
authors.lastname: van Solinge
authors.forename: Hubert G M
authors.initials: HG
authors.lastname: Leufkens
authors.forename: Jan-Willem J
authors.initials: JW
authors.lastname: Lammers
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D018450:Disease Progression; D017723:Drug Utilization Review / Q000706:statistics & numerical data* / Q000639:trends; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data / Q000639:trends; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011379:Prognosis; D011788:Quality of Life; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones