Rational: Worldwide, almost 70% of patients with COPD are undiagnosed. Case-finding interventions can identify symptomatic patients with COPD who may benefit from treatment. A better understanding of the symptom burden associated with undiagnosed COPD and the differences in this burden between men and women would be necessary to understand the impact of COPD and aid in the development of better targeted case-finding interventions.
The objectives of our study were i) to determine the symptom burden and functional limitations in patients with undiagnosed COPD and compare with healthy control; ii) to compare the symptom burden between men and women.
Methods: We used data from CanCOLD, a prospective population-based longitudinal cohort study that recruited non-institutionalized adults through random digit dialling (land line) from nine Canadian urban city sites. Patients with undiagnosed COPD, as defined by FEV1/FVC post bronchodilator <0.7 who had never been given a physician diagnosis of COPD, chronic bronchitis, or emphysema, were compared to matched healthy, never smokers without COPD. Undiagnosed COPD were compared to the healthy control.
Results: A total of 839 patients were included: 519 patients with undiagnosed COPD (191 women, 37%) and 320 healthy controls (170 women, 53%). The mean percent predicted FEV1 in undiagnosed COPD was 86.6% (+1-17.6) and was lower in women (85.2% +/-18.4) than men (90.4% +/-17.4). Patients with undiagnosed COPD had more respiratory symptoms, lower exercise tolerance, and lower quality of life than healthy controls.
The mean CAT score did not differ between undiagnosed COPD and controls but, for those with undiagnosed COPD, the CAT was higher for women than men. Women with undiagnosed COPD had a lower percent predicted FEV1, more symptoms, and lower quality of life than men, but had an equivalent exercise capacity, as measured by percent predicted peak V02.
Conclusion: Patients with undiagnosed COPD have symptoms including chronic cough, phlegm, and wheeze as well as more dyspnea, and reduced quality of life compared to healthy controls. They also have functional limitation with reduced 6MWT distances and decreased exercise capacity on cardiopulmonary exercise testing.
Some of these patients could benefit from diagnosis and treatment of their COPD. Women make up a smaller proportion of undiagnosed COPD than men, but have a higher symptom burden and more reduced health status. These differences should be taken into account when designing case-finding interventions.