Characteristics of subjects with undiagnosed COPD based on post-bronchodilator spirometry data

BACKGROUND: COPD is largely underdiagnosed. Patients with undiagnosed COPD need to be diagnosed to ensure early treatment institution. It is therefore relevant to obtain a more profound understanding of the characteristics of patients with undiagnosed COPD to improve COPD case finding. This study aimed to explore the characteristics of subjects with undiagnosed COPD from the United States National Health and Nutrition Examination Survey (NHANES) dataset (2007– 2012) based on post-bronchodilator spirometry. METHODS: A multitude of statistical tests were performed to explore the potential characteristics of subjects with undiagnosed COPD. A total of 1,098 subjects with a post-bronchodilator FEV ₁/FVC < 0.7 or lower limit of normal (LLN) were included in the final sample. RESULTS: Undiagnosed subjects experienced less phlegm (P <.001), wheezing (P <.001), and chest pain (P <.001) than subjects diagnosed with COPD. They were characterized by less shortness of breath (P <.001), fewer work/school days lost to wheezing (P <.001), less sleep disturbance (P <.001), and less difficulty socializing (P <.001). The undiagnosed subjects felt less depressed (P <.001). Additionally, they were less likely to have asthma (P <.001). The annual household income was higher among the undiagnosed subjects (P <.001), and they were also characterized by higher FEV ₁ (P <.001), and FVC (P <.001). CONCLUSIONS: Subjects with undiagnosed COPD were characterized by fewer symptoms and had better lung function than their diagnosed counterparts.