title: Variability of antibiotic prescribing in patients with chronic obstructive pulmonary disease exacerbations: a cohort study.
abstract: BACKGROUND
  The role of antibiotics in treating mild or moderate exacerbations in patients with acute chronic obstructive pulmonary disease (COPD) is unclear. The aims were to: (i) describe patient characteristics associated with acute exacerbations amongst a representative COPD population, (ii) explore the relationship between COPD severity and outcomes amongst patients with exacerbations, and (iii) quantify variability by general practice in prescribing of antibiotics for COPD exacerbations.
  
  
  METHODS
  A cohort of 62,747 patients with COPD was identified from primary care general practices (GP) in England, and linked to hospital admission and death certificate data. Exacerbation cases were matched to three controls and characteristics compared using conditional logistic regression. Outcomes were compared using incidence rates and Cox regression, stratified by disease severity. Variability of prescribing at the GP level was evaluated graphically and by using multilevel models.
  
  
  RESULTS
  COPD severity was found to be associated with exacerbation and subsequent mortality (very severe vs. mild, odds ratio for exacerbation 2.12 [95%CI 19.5-2.32]), hazard ratio for mortality 2.14 [95%CI 1.59-2.88]). Whilst 61% of exacerbation cases were prescribed antibiotics, this proportion varied considerably between GP practices (interquartile range, 48-73%). This variation is greater than can be explained by patient characteristics alone.
  
  
  CONCLUSIONS
  There is significant variability between GP practices in the prescribing of antibiotics to COPD patients experiencing exacerbations. Combined with a lack of evidence on the effects of treatment, this supports the need and opportunity for a large scale pragmatic randomised trial of the prescribing of antibiotics for COPD patients with exacerbations, in order to clarify their effectiveness and long term outcomes whilst ensuring the representativeness of subjects.
authors.affiliation: Clinical Practice Research Datalink, Medicines and Healthcare products Regulatory Agency, 151 Buckingham Palace Road, London SW1W 9SZ, UK.
authors.forename: Rachael
authors.initials: R
authors.lastname: Boggon
authors.forename: Richard
authors.initials: R
authors.lastname: Hubbard
authors.forename: Liam
authors.initials: L
authors.lastname: Smeeth
authors.forename: Martin
authors.initials: M
authors.lastname: Gulliford
authors.forename: Jackie
authors.initials: J
authors.lastname: Cassell
authors.forename: Susan
authors.initials: S
authors.lastname: Eaton
authors.forename: Munir
authors.initials: M
authors.lastname: Pirmohamed
authors.forename: Tjeerd-Pieter
authors.initials: TP
authors.lastname: van Staa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016022:Case-Control Studies; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010818:Practice Patterns, Physicians'; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000401:mortality; D012044:Regression Analysis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D015996:Survival Rate; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents