Introduction: Underdiagnosis of COPD appears to be common, although the degree of underdiagnosis is rarely measured. To document the extent of underdiagnosis in a high risk group of ambulatory patients, we performed spirometry in smokers aged 40 years and over drawn from general practices in two countries.
Methods: Subjects were recruited from primary care practices in Aberdeen, Scotland, and Denver, Colorado, via random mailing. Current and former smokers aged 40 or older with no prior diagnosis of chronic obstructive respiratory disease (and no respiratory medications within the past year) were enrolled. Participants underwent pre- and post-bronchodilator spirometry. A study diagnosis of COPD was defined as post-bronchodilator FEV1/FVC < 0.70. RESULTS Spirometric examination was complete in 818 patients, of whom 155 (18.9%) had a study diagnosis of COPD. Using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) severity criteria, the COPD was mild in 57.4%, moderate in 36.8%, and severe in 5.8%. No patients had very severe disease according to GOLD criteria.
Discussion: Screening of smokers over 40 in general practice may yield 10 - 20% undiagnosed COPD cases, with a substantial proportion of these having moderate to severe disease. Earlier diagnosis through targeted case-finding will allow early, aggressive smoking cessation efforts and may lead to a reduction in the burden of COPD symptoms and a reduced impact of the disease on health-related quality of life in these patients.