title: Impact of Prolonged Exacerbation Recovery in Chronic Obstructive Pulmonary Disease.
abstract: BACKGROUND
  Exacerbations are important and heterogeneous events in the natural history of chronic obstructive pulmonary disease (COPD).
  
  
  OBJECTIVE
  To examine the consequences of prolonged exacerbation recovery in patients with COPD.
  
  
  METHODS
  A cohort of 384 patients with COPD (FEV1 % predicted 45.8 [SD, 16.6] and a median exacerbation rate of 2.13 per year [interquartile range, 1.0-3.2]) were followed for 1,039 days (interquartile range, 660-1,814) between October 1995 and January 2013. Patients recorded daily worsening of respiratory symptoms and peak expiratory flow (PEF), and when stable underwent spirometry every 3 months, and completed the St. George's Respiratory Questionnaire annually. Exacerbations were diagnosed as 2 consecutive days with one major symptom plus another respiratory symptom. Exacerbation duration was defined as the time from onset to the day preceding 2 consecutive symptom-free days and recovery in PEF as return to preexacerbation levels.
  
  
  RESULTS
  A total of 351 patients had one or more exacerbations. Patients with a longer symptom duration (mean, 14.5 d) had a worse St. George's Respiratory Questionnaire total score (0.2 units per 1 day; P = 0.040). A longer symptomatic duration was associated with a shorter interval between exacerbation recovery and onset of the next exacerbation (hazard ratio, 1.004; P = 0.013). For 257 (7.3%) exacerbations, PEF did not recover within 99 days. These exacerbations were associated with symptoms of a viral infection (cold and sore throat). Patients with these nonrecovered exacerbations showed a 10.8 ml/yr (P < 0.001) faster decline in FEV1.
  
  
  CONCLUSIONS
  Prolonged exacerbation symptomatic duration is associated with poorer health status and a greater risk of a new event. Exacerbations where lung function does not recover are associated with symptoms of viral infections and accelerated decline in FEV1.
authors.affiliation: 1 Airways Disease Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; and.
authors.forename: Gavin C
authors.identifier: http://orcid.org/0000-0002-5538-4190
authors.initials: GC
authors.lastname: Donaldson
authors.affiliation: 2 MRC Biostatistics Unit, Cambridge Institute of Public Health, Forvie Site, Robinson Way, Cambridge Biomedical Campus, Cambridge, United Kingdom.
authors.forename: Martin
authors.initials: M
authors.lastname: Law
authors.affiliation: 1 Airways Disease Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; and.
authors.forename: Beverly
authors.initials: B
authors.lastname: Kowlessar
authors.affiliation: 1 Airways Disease Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; and.
authors.forename: Richa
authors.initials: R
authors.lastname: Singh
authors.affiliation: 1 Airways Disease Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; and.
authors.forename: Simon E
authors.initials: SE
authors.lastname: Brill
authors.affiliation: 1 Airways Disease Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; and.
authors.forename: James P
authors.initials: JP
authors.lastname: Allinson
authors.affiliation: 1 Airways Disease Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom; and.
authors.forename: Jadwiga A
authors.initials: JA
authors.lastname: Wedzicha
mesh_terms: D000368:Aged; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D010612:Pharyngitis / Q000453:epidemiology; D016016:Proportional Hazards Models; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology / Q000503:physiopathology*; D011788:Quality of Life; D020127:Recovery of Function; D012141:Respiratory Tract Infections / Q000453:epidemiology; D012307:Risk Factors; D013997:Time Factors; D014777:Virus Diseases / Q000453:epidemiology; D014797:Vital Capacity
keywords: COPD; exacerbations; nonrecovery; recovery; risk interval