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Canadian Respiratory Journal
Volume 18 (2011), Issue 6, Pages 327-332
Original Article

Mortality among Subjects with Chronic Obstructive Pulmonary Disease or Asthma at Two Respiratory Disease Clinics in Ontario

Murray M Finkelstein,1 Kenneth R Chapman,2 R Andrew McIvor,3 and Malcolm R Sears3

1Granovsky-Gluskin Family Medicine Centre, Mount Sinai Hospital, Canada
2Asthma and Airway Centre, University Health Network, Toronto, Canada
3Firestone Institute for Respiratory Health, St Joseph’s Healthcare, Hamilton, Ontario, Canada

Copyright © 2011 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


BACKGROUND: Chronic obstructive pulmonary disease (COPD) and asthma are common; however, mortality rates among individuals with these diseases are not well studied in North America.

OBJECTIVE: To investigate mortality rates and risk factors for premature death among subjects with COPD.

METHODS: Subjects were identified from the lung function testing databases of two academic respiratory disease clinics in Hamilton and Toronto, Ontario. Mortality was ascertained by linkage to the Ontario mortality registry between 1992 and 2002, inclusive. Standardized mortality ratios were computed. Poisson regression of standardized mortality ratios and proportional hazards regression were performed to examine the multivariate effect of risk factors on the standardized mortality ratios and mortality hazards.

RESULTS: Compared with the Ontario population, all-cause mortality was approximately doubled among subjects with COPD, but was lower than expected among subjects with asthma. The risk of mortality in patients with COPD was related to cigarette smoking, to the presence of comorbid conditons of ischemic heart disease and diabetes, and to Global initiative for chronic Obstructive Lung Disease severity scores. Individuals living closer to traffic sources showed an elevated risk of death compared with those who lived further away from traffic sources.

CONCLUSIONS: Mortality rates among subjects diagnosed with COPD were substantially elevated. There were several deaths attributed to asthma among subjects in the present study; however, overall, patients with asthma demonstrated lower mortality rates than the general population. Subjects with COPD need to be managed with attention devoted to both their respiratory disorders and related comorbidities.