Pre- and post-bronchodilator airway obstruction are associated with similar clinical characteristics but different prognosis - report from a population-based study

Abstract

Introduction: According to guidelines, the diagnosis of COPD should be confirmed by post-bronchodilator (post-BD) airway obstruction on spirometry; however, in clinical practice, this is not always performed. The aim of this population-based study was to compare clinical characteristics and prognosis, assessed as mortality, between subjects with airway obstruction divided into pre- but not post-BD obstruction, post-BD airway obstruction (COPD), and subjects without airway obstruction.

Materials and methods: In 2002-2004, four adult population-based cohorts were reexamined with spirometry and structured interview. Subjects with airway obstruction, with a ratio of forced expiratory volume in 1 s to (forced) vital capacity <0.70 (n=993), were identified together with sex- and age-matched referents (n=993). These subjects were further divided into subjects with pre- but not post-BD airway obstruction (pre- not post-BD obstruction) and subjects with post-BD airway obstruction (COPD). Mortality data were collected until December 31, 2014.

Results: Out of 993 subjects with airway obstruction, 736 (74%) had COPD and 257 (26%) pre- not post-BD obstruction. Any respiratory symptoms, allergic rhinitis, asthma, exacerbations, and comorbidities were equally common among subjects with COPD and pre- not post-BD obstruction, but less common among nonobstructive subjects. Mortality was highest among subjects with COPD and higher in men than in women. In both sexes, COPD, but not pre- not post-BD obstruction, was associated with an increased risk for death compared to those without airway obstruction. When COPD was divided into Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages, GOLD 2 and 3-4 had an increased risk for death when compared to the nonobstructive group, also when adjusted for common confounders and comorbidities such as heart disease, diabetes, and anxiety/depression.

Conclusion: Even though subjects with COPD and pre- not post-BD obstruction had fairly similar presentation of clinical characteristics, only those with COPD, specifically GOLD stage ≥2, had increased risk for death when compared with nonobstructive subjects.

Keywords: chronic airflow obstructions; epidemiology; mortality; spirometry.

Figure 1

Study population by spirometric classification. Note: ^aPost-BD obstructive; fullfilling the spirometric criteria for COPD according to GOLD. Abbreviations: BD, bronchodilator; FEV₁, forced expiratory volume in 1 s; GOLD, Global Initiative for Chronic Obstruc tive Lung Disease; VC, vital capacity.

Figure 2

Survival among nonobstructive, pre-BD obstructive, and COPD (A) illustrated by Kaplan–Meier curves, (B) divided into GOLD 1, GOLD 2, and GOLD 3–4 illustrated by Kaplan–Meier curves. Abbreviations: BD, bronchodilator; GOLD, Global Initiative for Chronic Obstructive Lung Disease.