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Healthcare system encounters before COPD diagnosis: a registry-based longitudinal cohort study
  1. Kate M Johnson1,
  2. Amir Khakban1,
  3. Stirling Bryan2,
  4. Don D Sin3,4,
  5. Mohsen Sadatsafavi1,2
  1. 1 Respiratory Evaluation Sciences Program, Collaboration for Outcomes Research and Evaluation, The University of British Columbia Faculty of Pharmaceutical Sciences, Vancouver, British Columbia, Canada
  2. 2 Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, British Columbia, Canada
  3. 3 University of British Columbia Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
  4. 4 Institute for Heart and Lung Health, The University of British Columbia Department of Medicine, Vancouver, British Columbia, Canada
  1. Correspondence to Kate M Johnson, Respiratory Evaluation Sciences Program, Collaboration for Outcomes Research and Evaluation, The University of British Columbia Faculty of Pharmaceutical Sciences, Vancouver, BC V6T 1Z3, Canada; kate.johnson{at}


Background There is high interest in strategies for improving early detection of chronic obstructive pulmonary disease (COPD). These strategies often rely on opportunistic encounters between patients with undiagnosed COPD and the healthcare system; however, the frequency of these encounters is currently unknown.

Methods We used administrative health data for the province of British Columbia, Canada, from 1996 to 2015. We identified patients with COPD using a validated case definition, and assessed their visits to pharmacists, primary care and specialist physicians in the 5 years prior to the initial diagnosis of COPD. We used generalised linear models to compare the rate of outpatient visits between COPD and non-COPD comparator subjects matched on age, sex and socioeconomic status.

Results We assessed 112 635 COPD and non-COPD pairs (mean 68.6 years, 51.0% male). Patients with COPD interacted with pharmacists most frequently in the 5 years before diagnosis (mean 14.09, IQR 4–17 visits/year), followed by primary care (10.29, IQR 4–13 visits/year) and specialist (8.11, IQR 2–11 visits/year) physicians. In the 2 years prior to diagnosis, 72.1% of patients with COPD had a respiratory-related primary care visit that did not result in a COPD diagnosis. Compared with non-COPD subjects, patients with COPD had higher rates of primary care (rate ratio (RR) 1.40, 95% CI 1.39 to 1.41), specialist (RR 1.35, 95% CI 1.34 to 1.37) and pharmacist (RR 1.62, 95% CI 1.60 to 1.63) encounters.

Conclusions Patients with COPD used higher rates of outpatient services before diagnosis than non-COPD subjects. Case detection technologies implemented in pharmacy or primary care settings have opportunities to diagnose COPD earlier.

  • COPD epidemiology
  • health economist

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  • Collaborators for the Canadian Respiratory Research Network

  • Contributors MS, SB and KMJ formulated the study idea. AK prepared the data. KMJ performed all data analyses and wrote the first draft of the manuscript. All authors contributed to interpretation of findings, critically commented on the manuscript and approved the final version. KMJ is the guarantor of the manuscript.

  • Funding This study was funded by a Canadian Lung Association Breathing as One Studentship Award and the Canadian Institutes of Health Research (application number 142238).

  • Disclaimer The funders had no role in study design, data collection and analysis, or preparation of the manuscript.

  • Competing interests DDS has received honoraria for speaking engagements from Boehringer Ingelheim (BI), AstraZeneca (AZ) and Novartis; has served on COPD advisory committees for AZ; Sanofi-Aventis and CSA; and has received research funding from AZ, BI and Merck, outside the submitted work.

  • Patient consent for publication Not required.

  • Ethics approval Ethics approval was obtained from Population Data British Columbia (BC) (H13-00684).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement The data used for this study were provided by British Columbia’s Ministry of Health. These are anonymised health care resource use data of legal residents of the province. The data are protected by the Freedom of Information and Protection of Privacy Act (FIPPA) and as such cannot be shared to any entity outside of the province. FIPPA not only prohibits the storage of personal information outside of Canada, but it also prohibits access, which includes viewing. Please refer to for further information. Data requests can be sent to and general enquiries about the data should be addressed to

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