Chronic obstructive pulmonary disease in primary care: an epidemiologic cohort study from the Canadian Primary Care Sentinel Surveillance Network

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is mostly managed within primary care, but there is little Canadian evidence from this setting. This study was undertaken to determine the prevalence of physician-diagnosed COPD in primary care practices, and the degree of comorbidity with other chronic conditions, and to assess patterns of medication prescribing.

Methods: The Canadian Primary Care Sentinel Surveillance Network is a national "network of networks" whose member practices use electronic medical records (EMRs). At the time of the study, it included data from 444 physicians from 10 networks in 8 provinces. We conducted an epidemiologic cohort study of all patients who had EMR data collected by the network at the end of 2012. Validated case-finding algorithms were used to identify cases of COPD. We used descriptive statistics and multivariate modelling analyses to calculate the prevalence of COPD, its association with key demographic factors and comorbidities, and patterns of medication prescribing.

Results: The observed prevalence of COPD was 4.0% (10 043/250 346), which represents a population prevalence of 3.4% using age-sex standardization. Comorbidity was common, with prevalence ratios ranging from 1.1 for the presence of a single comorbid condition to 1.9 for 4 or more comorbid conditions. Anticholinergic agents (63%), short- (48%) and long-acting (38%) β-agonists and inhaled corticosteroids (41%) were the most commonly used medications.

Interpretation: The prevalence of physician-diagnosed COPD in Canadian primary care practices was similar to that reported in other practice-based studies at about 3%-4%. Most patients had comorbid conditions and were taking multiple medications. EMR data may be useful to assess both the epidemiology and management of COPD in primary care practices.

Figure 1:

Prevalence of chronic obstructive pulmonary disease (COPD) in patients aged 40 years and older. Data source: Canadian Primary Care Sentinel Surveillance Network 2012.

Figure 2:

Mean number of comorbid conditions, by age and COPD status. The mean difference for each age group except 18–29 years is significant at p < 0.001. Data source: Canadian Primary Care Sentinel Surveillance Network 2012.