RT Journal Article SR Electronic T1 Outcomes of patients with chronic obstructive pulmonary disease diagnosed with or without pulmonary function testing JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP E530 OP E538 DO 10.1503/cmaj.151420 VO 189 IS 14 A1 Andrea Gershon A1 Graham Mecredy A1 Ruth Croxford A1 Teresa To A1 Matthew B. Stanbrook A1 Shawn D. Aaron A1 , YR 2017 UL http://www.cmaj.ca/content/189/14/E530.abstract AB 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).INTERPRETATION: 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.