Can We Use Lung Function Thresholds and Respiratory Symptoms to Identify Pre-Chronic Obstructive Pulmonary Disease? A Prospective, Population-based Cohort Study.

Rationale: The term "pre-chronic obstructive pulmonary disease" ("pre-COPD") refers to individuals at high risk of developing COPD who do not meet conventional spirometric criteria for airflow obstruction. New approaches to identifying these individuals are needed, particularly in younger populations. Objectives: To determine whether lung function thresholds and respiratory symptoms can be used to identify individuals at risk of developing COPD. Methods: The Tasmanian Longitudinal Health Study comprises a population-based cohort first studied in 1968 (at age 7 yr). Respiratory symptoms, pre- and post-bronchodilator (BD) spirometry, diffusing capacity, and static lung volumes were measured in a subgroup at age 45, and the incidence of COPD was assessed at age 53. For each lung function measure, z-scores were calculated using Global Lung Function Initiative references. The optimal threshold for best discrimination of COPD incidence was determined by the unweighted Youden index. Measurements and Main Results: Among 801 participants who did not have COPD at age 45, the optimal threshold for COPD incidence by age 53 was pre-BD FEV1/FVC z-score less than -1.264, corresponding to the lowest 10th percentile. Those below this threshold had a 36-fold increased risk of developing COPD over an 8-year follow-up period (risk ratio, 35.8; 95% confidence interval, 8.88 to 144), corresponding to a risk difference of 16.4% (95% confidence interval, 3.7 to 67.4). The sensitivity was 88%, and the specificity was 87%. Positive and negative likelihood ratios were 6.79 and 0.14, respectively. Respiratory symptoms, post-BD spirometry, diffusing capacity, and static lung volumes did not improve on the classification achieved by pre-BD FEV1/FVC alone. Conclusions: This is the first study, to our knowledge, to evaluate the discriminatory accuracy of spirometry, diffusing capacity, and static lung volume thresholds for COPD incidence in middle-aged adults. Our findings support the inclusion of pre-BD spirometry in the physiological definition of pre-COPD and indicate that pre-BD FEV1/FVC at the 10th percentile accurately identifies individuals at high risk of developing COPD in community-based settings.

Risk factors and clinical characteristics of breathlessness in Australian adults: Data from the BOLD Australia study.

BACKGROUND: Breathlessness is a common symptom related to a significant health burden. However, the association of breathlessness with clinical characteristics, especially objective pulmonary test results is scarce. We aimed to identify the characteristics independently associated with breathlessness in Australian adults. METHOD: The analysis used data from BOLD Australia, a cross-sectional study that included randomly selected adults aged ≥40 years from six sites in Australia. Clinical characteristics and spirometry results were compared for breathlessness (modified Medical Research Council [mMRC] grade ≥2). RESULTS: Among all respondents (n = 3321), 252 participants (7.6%) reported breathlessness. The main univariate associations were obesity, chronic respiratory diseases, heart diseases and being Indigenous Australians (odds ratios [ORs] = 2.78, 5.20, 3.77 and 4.38, respectively). Participants with breathlessness had lower pre-and post-bronchodilator lung function than those without. Impaired spirometry results including FVC or FEV1 below 80% predicted, or FEV1/FVC < LLN were independently associated with breathlessness (adjusted ORs = 2.66, 2.94 and 2.34, respectively). CONCLUSIONS: Breathlessness is common among Australian adults and is independently associated with obesity, chronic respiratory diseases, heart diseases, being Indigenous Australians, and impaired spirometry. Multi-disciplinary assessment and comprehensive investigation is needed in clinical practice to address the many factors associated with breathlessness in the population.

COPD in Never-Smokers: BOLD Australia Study.

Purpose: Tobacco smoking is the major risk factor for COPD, and it is common for other risk factors in never-smokers to be overlooked. We examined the prevalence of COPD among never-smokers in Australia and identified associated risk factors. Methods: We used data from the Australia Burden of Obstructive Lung Disease (BOLD) study, a cross-section of people aged ≥40 years from six sites. Participants completed interviews and post-bronchodilator spirometry. COPD was primarily defined as an FEV1/FVC ratio <0.70 and secondarily as the ratio less than the lower limit of normal (LLN). Results: The prevalence of COPD in the 1656 never-smokers who completed the study was 10.5% (95% CI: 9.1-12.1%) [ratio