title: Factors associated with change in exacerbation frequency in COPD.
abstract: BACKGROUND
  Patients with chronic obstructive pulmonary disease (COPD) can be categorized as having frequent (FE) or infrequent (IE) exacerbations depending on whether they respectively experience two or more, or one or zero exacerbations per year. Although most patients do not change category from year to year, some will, and the factors associated with this behaviour have not been examined.
  
  
  METHODS
  1832 patients completing two year follow-up in the Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE) study were examined at baseline and then yearly. Exacerbations were defined by health care utilisation. Patient characteristics compared between those patients who did or did not change exacerbation category from year 1 to year 2.
  
  
  RESULTS
  Between years 1 and 2, 221 patients (17%) changed from IE to FE and 210 patients (39%) from FE to IE. More severe disease was associated with changing from IE to FE and less severe disease from FE to IE. Over the preceding year, small falls in FEV1 and 6-minute walking distance were associated with changing from IE to FE, and small falls in platelet count associated with changing from FE to IE.
  
  
  CONCLUSIONS
  No parameter clearly predicts an imminent change in exacerbation frequency category.
  
  
  BACKGROUND
  SCO104960, clinicaltrials.gov identifier NCT00292552.
authors.affiliation: Centre for Respiratory Medicine, UCL Medical School, Royal Free Campus, Rowland Hill Street Hampstead, London NW3 2PF, UK. g.donaldson@ucl.ac.uk
authors.forename: Gavin C
authors.initials: GC
authors.lastname: Donaldson
authors.forename: Hanna
authors.initials: H
authors.lastname: Müllerova
authors.forename: Nicholas
authors.initials: N
authors.lastname: Locantore
authors.forename: John R
authors.initials: JR
authors.lastname: Hurst
authors.forename: Peter M A
authors.initials: PM
authors.lastname: Calverley
authors.forename: Jorgen
authors.initials: J
authors.lastname: Vestbo
authors.forename: Antonio
authors.initials: A
authors.lastname: Anzueto
authors.forename: Jadwiga A
authors.initials: JA
authors.lastname: Wedzicha
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D018450:Disease Progression; D005080:Exercise Test / Q000706:statistics & numerical data*; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000453:epidemiology*; D012307:Risk Factors; D017678:Sex Distribution; D012907:Smoking / Q000453:epidemiology*; D006113:United Kingdom / Q000453:epidemiology
references.citation: Lancet. 2007 Sep 1;370(9589):786-96
references.pmid: 17765528
references.citation: Crit Care. 2011 Jul 08;15(4):R163
references.pmid: 21740551
references.citation: Arch Med Res. 2006 Aug;37(6):755-9
references.pmid: 16824936
references.citation: Respir Res. 2013 Jul 30;14:79
references.pmid: 23899210
references.citation: Eur Respir J. 2004 Jan;23(1):28-33
references.pmid: 14738227
references.citation: Thorax. 2000 Feb;55(2):114-20
references.pmid: 10639527
references.citation: Acad Radiol. 2011 Jun;18(6):661-71
references.pmid: 21393027
references.citation: Am J Respir Crit Care Med. 1998 May;157(5 Pt 1):1418-22
references.pmid: 9603117
references.citation: Respir Res. 2011 Nov 04;12:146
references.pmid: 22054035
references.citation: Eur Respir J Suppl. 1993 Mar;16:5-40
references.pmid: 8499054
references.citation: Thorax. 2006 Jun;61(6):472-7
references.pmid: 16517577
references.citation: Am J Respir Crit Care Med. 2004 Jun 15;169(12):1298-303
references.pmid: 14990395
references.citation: Eur Respir J. 2011 Mar;37(3):501-7
references.pmid: 20650988
references.citation: Antioxid Redox Signal. 2012 Nov 15;17(10):1447-85
references.pmid: 22458931
references.citation: Respir Res. 2010 Sep 10;11:122
references.pmid: 20831787
references.citation: N Engl J Med. 2010 Sep 16;363(12):1128-38
references.pmid: 20843247
references.citation: N Engl J Med. 2011 Sep 29;365(13):1184-92
references.pmid: 21991892
references.citation: Respir Care. 2003 Dec;48(12):1204-13; discussion 1213-5
references.pmid: 14651761
references.citation: Value Health. 2001 Sep-Oct;4(5):370-5
references.pmid: 11705127
references.citation: N Engl J Med. 2008 Oct 9;359(15):1543-54
references.pmid: 18836213
references.citation: Value Health. 2004 Mar-Apr;7(2):153-67
references.pmid: 15164805
references.citation: Chest. 2006 Feb;129(2):317-324
references.pmid: 16478847
references.citation: Am J Respir Crit Care Med. 2013 Feb 15;187(4):347-65
references.pmid: 22878278
references.citation: Eur Respir J. 2011 Aug;38(2):261-7
references.pmid: 21177838
references.citation: Am J Respir Crit Care Med. 2001 Nov 1;164(9):1618-23
references.pmid: 11719299
references.citation: Thorax. 2002 Oct;57(10):847-52
references.pmid: 12324669
references.citation: Br J Pharmacol. 2007 Dec;152(7):987-1002
references.pmid: 17603547
references.citation: Eur Respir J. 2010 May;35(5):1022-30
references.pmid: 19897555
references.citation: Clin Ther. 2011 Oct;33(10):1365-70
references.pmid: 21962452
references.citation: N Engl J Med. 2004 Mar 4;350(10):1005-12
references.pmid: 14999112
references.citation: Thorax. 2005 Nov;60(11):925-31
references.pmid: 16055622
references.citation: Eur Respir J. 2008 Apr;31(4):869-73
references.pmid: 18216052
references.citation: J Clin Epidemiol. 2010 Dec;63(12):1324-31
references.pmid: 20800447
references.citation: Int J Chron Obstruct Pulmon Dis. 2010 Dec 09;5:435-44
references.pmid: 21191438
references.citation: Am J Respir Crit Care Med. 2000 May;161(5):1608-13
references.pmid: 10806163
references.citation: Am J Respir Crit Care Med. 1998 Nov;158(5 Pt 1):1384-7
references.pmid: 9817683
references.citation: Eur Respir J. 2003 Dec;22(6):931-6
references.pmid: 14680081
references.citation: Respir Med. 2010 Jun;104(6):849-57
references.pmid: 20471236
references.citation: Platelets. 2011;22(6):466-70
references.pmid: 21506665