title: Outcomes of patients with chronic obstructive pulmonary disease diagnosed with or without pulmonary function testing.
abstract: BACKGROUND
  A small number of people with chronic obstructive pulmonary disease (COPD) receive pulmonary function testing around the time of diagnosis. Because omitting testing increases misdiagnosis, we sought to determine whether health outcomes differed between patients whose COPD was diagnosed with or without pulmonary function testing.
  
  
  METHODS
  We conducted a longitudinal population study of patients with physician-diagnosed COPD from 2005 to 2012 using health administrative data from Ontario, Canada. We assessed whether having pulmonary function testing around the time of diagnosis was associated with the composite outcome of admission to hospital for COPD or all-cause death, using adjusted survival analysis.
  
  
  RESULTS
  Chronic obstructive pulmonary disease was diagnosed in 68 898 patients during the study period; 41.2% of patients received peridiagnostic pulmonary function testing. In adjusted analysis, patients who underwent testing were less likely to die or be admitted to hospital for COPD (adjusted hazard ratio [HR] 0.91, 95% confidence interval [CI] 0.89-0.94) and were more likely to be prescribed an inhaled long-acting bronchodilator than patients who did not undergo testing. Subgroup analysis suggested that the association of testing and outcomes was confined to patients with COPD diagnosed in the ambulatory care setting (adjusted HR 0.80, 95% CI 0.76-0.84).
  
  
  CONCLUSIONS
  Confirmation of a COPD diagnosis using pulmonary function testing is associated with a decreased risk of death and admission to hospital for COPD. In ambulatory patients, this effect may be from increased use of appropriate COPD medications. The findings of this study validate current guideline recommendations that encourage pulmonary function testing for diagnosis in all patients with suspected COPD.
authors.affiliation: Institute for Clinical Evaluative Sciences (Gershon, Mecredy, Croxford, To, Stanbrook); Sunnybrook Health Sciences Centre (Gershon); Institute of Health Policy, Management and Evaluation (Gershon, Stanbrook) and Dalla Lana School of Public Health (To), University of Toronto; The Hospital for Sick Children (To); University Health Network (Stanbrook), Toronto, Ont.; Ottawa Hospital Research Institute (Aaron), University of Ottawa, Ottawa, Ont. andrea.gershon@ices.on.ca.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gershon
authors.affiliation: Institute for Clinical Evaluative Sciences (Gershon, Mecredy, Croxford, To, Stanbrook); Sunnybrook Health Sciences Centre (Gershon); Institute of Health Policy, Management and Evaluation (Gershon, Stanbrook) and Dalla Lana School of Public Health (To), University of Toronto; The Hospital for Sick Children (To); University Health Network (Stanbrook), Toronto, Ont.; Ottawa Hospital Research Institute (Aaron), University of Ottawa, Ottawa, Ont.
authors.forename: Graham
authors.initials: G
authors.lastname: Mecredy
authors.affiliation: Institute for Clinical Evaluative Sciences (Gershon, Mecredy, Croxford, To, Stanbrook); Sunnybrook Health Sciences Centre (Gershon); Institute of Health Policy, Management and Evaluation (Gershon, Stanbrook) and Dalla Lana School of Public Health (To), University of Toronto; The Hospital for Sick Children (To); University Health Network (Stanbrook), Toronto, Ont.; Ottawa Hospital Research Institute (Aaron), University of Ottawa, Ottawa, Ont.
authors.forename: Ruth
authors.initials: R
authors.lastname: Croxford
authors.affiliation: Institute for Clinical Evaluative Sciences (Gershon, Mecredy, Croxford, To, Stanbrook); Sunnybrook Health Sciences Centre (Gershon); Institute of Health Policy, Management and Evaluation (Gershon, Stanbrook) and Dalla Lana School of Public Health (To), University of Toronto; The Hospital for Sick Children (To); University Health Network (Stanbrook), Toronto, Ont.; Ottawa Hospital Research Institute (Aaron), University of Ottawa, Ottawa, Ont.
authors.forename: Teresa
authors.initials: T
authors.lastname: To
authors.affiliation: Institute for Clinical Evaluative Sciences (Gershon, Mecredy, Croxford, To, Stanbrook); Sunnybrook Health Sciences Centre (Gershon); Institute of Health Policy, Management and Evaluation (Gershon, Stanbrook) and Dalla Lana School of Public Health (To), University of Toronto; The Hospital for Sick Children (To); University Health Network (Stanbrook), Toronto, Ont.; Ottawa Hospital Research Institute (Aaron), University of Ottawa, Ottawa, Ont.
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Stanbrook
authors.affiliation: Institute for Clinical Evaluative Sciences (Gershon, Mecredy, Croxford, To, Stanbrook); Sunnybrook Health Sciences Centre (Gershon); Institute of Health Policy, Management and Evaluation (Gershon, Stanbrook) and Dalla Lana School of Public Health (To), University of Toronto; The Hospital for Sick Children (To); University Health Network (Stanbrook), Toronto, Ont.; Ottawa Hospital Research Institute (Aaron), University of Ottawa, Ottawa, Ont.
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Aaron
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002423:Cause of Death; D015897:Comorbidity; D016208:Databases, Factual; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000401:mortality*; D012129:Respiratory Function Tests / Q000706:statistics & numerical data*; D016019:Survival Analysis