title: Risk factors for acute exacerbations of COPD in a primary care population: a retrospective observational cohort study.
abstract: OBJECTIVE
  To evaluate risk factors associated with exacerbation frequency in primary care. Information on exacerbations of chronic obstructive pulmonary disease (COPD) has mainly been generated by secondary care-based clinical cohorts.
  
  
  METHODS
  Retrospective observational cohort study.
  
  
  METHODS
  Electronic medical records database (England and Wales).
  
  
  METHODS
  58,589 patients with COPD aged ≥40 years with COPD diagnosis recorded between 1 April 2009 and 30 September 2012, and with at least 365 days of follow-up before and after the COPD diagnosis, were identified in the Clinical Practice Research Datalink. Mean age: 69 years; 47% female; mean forced expiratory volume in 1s 60% predicted.
  
  
  METHODS
  Data on moderate or severe exacerbation episodes defined by diagnosis and/or medication codes 12 months following cohort entry were retrieved, together with demographic and clinical characteristics. Associations between patient characteristics and odds of having none versus one, none versus frequent (≥2) and one versus frequent exacerbations over 12 months follow-up were evaluated using multivariate logistic regression models.
  
  
  RESULTS
  During follow-up, 23% of patients had evidence of frequent moderate-to-severe COPD exacerbations (24% one; 53% none). Independent predictors of increased odds of having exacerbations during the follow-up, either frequent episodes or one episode, included prior exacerbations, increasing dyspnoea score, increasing grade of airflow limitation, females and prior or current history of several comorbidities (eg, asthma, depression, anxiety, heart failure and cancer).
  
  
  CONCLUSIONS
  Primary care-managed patients with COPD at the highest risk of exacerbations can be identified by exploring medical history for the presence of prior exacerbations, greater COPD disease severity and co-occurrence of other medical conditions.
authors.affiliation: Worldwide Epidemiology, GlaxoSmithKline, Uxbridge, UK.
authors.forename: Hana
authors.initials: H
authors.lastname: Müllerová
authors.affiliation: Worldwide Epidemiology, GlaxoSmithKline, Uxbridge, UK.
authors.forename: Amit
authors.initials: A
authors.lastname: Shukla
authors.affiliation: Global Respiratory Franchise, GlaxoSmithKline, Uxbridge, UK.
authors.forename: Adam
authors.initials: A
authors.lastname: Hawkins
authors.affiliation: London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Quint
mesh_terms: D000208:Acute Disease / Q000453:epidemiology; D000368:Aged; D001249:Asthma / Q000150:complications; D015897:Comorbidity; D018450:Disease Progression; D004417:Dyspnea / Q000150:complications; D057286:Electronic Health Records; D004739:England / Q000453:epidemiology; D005260:Female; D005541:Forced Expiratory Volume; D006296:Health Services; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D014852:Wales / Q000453:epidemiology
keywords: PRIMARY CARE; chronic obstructive pulmonary disease; database; electronic medical records; exacerbations