Pulmonary function and atherosclerosis in the general population: causal associations and clinical implications.

Reduced lung function is associated with cardiovascular mortality, but the relationships with atherosclerosis are unclear. The population-based Swedish CArdioPulmonary BioImage study measured lung function, emphysema, coronary CT angiography, coronary calcium, carotid plaques and ankle-brachial index in 29,593 men and women aged 50-64 years. The results were confirmed using 2-sample Mendelian randomization. Lower lung function and emphysema were associated with more atherosclerosis, but these relationships were attenuated after adjustment for cardiovascular risk factors. Lung function was not associated with coronary atherosclerosis in 14,524 never-smokers. No potentially causal effect of lung function on atherosclerosis, or vice versa, was found in the 2-sample Mendelian randomization analysis. Here we show that reduced lung function and atherosclerosis are correlated in the population, but probably not causally related. Assessing lung function in addition to conventional cardiovascular risk factors to gauge risk of subclinical atherosclerosis is probably not meaningful, but low lung function found by chance should alert for atherosclerosis.

Inhomogeneity of ventilation in smokers and mild COPD assessed by the ratio of alveolar volume to total lung capacity.

BACKGROUND: Previous studies have shown that the ratio between alveolar volume (VA) and total lung capacity (TLC) reflects ventilation heterogeneity in subjects with chronic obstructive pulmonary disease (COPD). However, the ratio and its correlation to respiratory symptoms had to our knowledge not previously been investigated in subjects with mild chronic airflow obstruction or without airflow obstruction (normal ratio FEV1/VC). The purpose of this study was to investigate potential connection between VA/TLC and respiratory symptoms, smoking habits and lung function parameters in subjects with normal spirometry and with mild chronic airflow obstruction. METHODS: We examined 450 subjects (82 non-smokers with normal spirometry, 298 subjects who smoked or had smoked earlier but had a normal spirometry and 70 subjects with chronical airflow obstruction) with routine lung function tests and a questionnaire regarding respiratory symptoms. RESULTS: This study showed 31 out of 54 subjects with a low VA/TLC had a normal ratio FEV1/VC. Of these subjects, 58.1 % had respiratory symptoms, compared to the group with normal ratio for both VA/TLC and FEV1/VC where 35.8 % had respiratory symptoms (p-value 0.02). CONCLUSION: This study has shown that within the group of subjects with a normal ratio FEV1/VC, those with a decreased ratio VA/TLC had a higher prevalence of respiratory symptoms compared to subjects with a normal VA/TLC ratio. These findings indicate that including the ratio VA/TLC in the evaluation of a pulmonary function test assessment might increase the possibility to identify subjects with early or at risk of lung disease.

Factors most strongly associated with breathlessness in a population aged 50-64 years.

Background: Breathlessness is a troublesome and prevalent symptom in the population, but knowledge of related factors is scarce. The aim of this study was to identify the factors most strongly associated with breathlessness in the general population and to describe the shapes of the associations between the main factors and breathlessness. Methods: A cross-sectional analysis was carried out of the multicentre population-based Swedish CArdioPulmonary bioImage Study (SCAPIS) of adults aged 50 to 64 years. Breathlessness was defined as a modified Medical Research Council breathlessness rating ≥2. The machine learning algorithm extreme gradient boosting (XGBoost) was used to classify participants as either breathless or nonbreathless using 449 factors, including physiological measurements, blood samples, computed tomography cardiac and lung measurements, lifestyle, health conditions and socioeconomics. The strength of the associations between the factors and breathlessness were measured by SHapley Additive exPlanations (SHAP), with higher scores reflecting stronger associations. Results: A total of 28 730 participants (52% women) were included in the study. The strongest associated factors for breathlessness were (in order of magnitude): body mass index ( SHAP score 0.39), forced expiratory volume in 1 s (0.32), physical activity measured by accelerometery (0.27), sleep apnoea (0.22), diffusing lung capacity for carbon monoxide (0.21), self-reported physical activity (0.17), chest pain when hurrying (0.17), high-sensitivity C-reactive protein (0.17), recent weight change (0.14) and cough (0.13). Conclusion: This large population-based study of men and women aged 50-64 years identified the main factors related to breathlessness that may be prevented or amenable to public health interventions.

Restrictive Spirometric Pattern and Preserved Ratio Impaired Spirometry in a Population 50-64 Years.

RATIONALE: Knowledge regarding prevalence and shared and unique characteristics of Restrictive spirometric pattern (RSP) and Preserved ratio impaired spirometry (PRISm) is lacking for a general population investigated with post-bronchodilator spirometry and computed tomography of the lungs. OBJECTIVES: To investigate shared and unique features for RSP and PRISm. METHODS: In the Swedish CArdioPulmonary bioImage Study (SCAPIS), a general population sample of 28,555 people aged 50 - 64 years (including 14,558 never-smokers) was assessed. The participants answered a questionnaire and underwent computed tomography of the lungs, post-bronchodilator spirometry, and coronary artery calcification score (CACS). Odds ratios (OR) with 95% confidence intervals (CI) were calculated using adjusted logistic regression. RSP was defined as FEV1/FVC≥0.70 and FVC<80%. PRISm was defined as FEV1/FVC≥0.70 and FEV1<80%. A local reference equation was applied. MEASUREMENTS AND RESULTS: The prevalence of RSP and PRISm were 5.1% (95% CI 4.9 - 5.4) and 5.1% (95% CI 4.8 - 5.3), respectively, with similar values seen in never-smokers. For RSP and PRISm, shared features were current smoking, dyspnea, chronic bronchitis, rheumatic disease, diabetes, ischemic heart disease (IHD), bronchial wall thickening, interstitial lung abnormalities (ILA), and bronchiectasis. Emphysema was uniquely linked to PRISm (OR 1.69, 1.36-2.10) vs 1.10 (0.84-1.43) for RSP. CACS≥300 was related to PRISm, but not among among never-smokers. CONCLUSIONS: PRISm and RSP have respiratory, cardiovascular, and metabolic conditions as shared features. Emphysema is only associated with PRISm. Coronary atherosclerosis may be associated with PRISm. Our results indicate that RSP and PRISm may share more features than not. This article is open access and distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).

Chronic Airflow Limitation, Emphysema and Impaired Diffusing Capacity in Relation to Smoking Habits in a Swedish Middle-Aged Population.

RATIONALE: Chronic obstructive pulmonary disease (COPD) includes respiratory symptoms and chronic airflow limitation (CAL). In some cases, emphysema and impaired diffusing capacity for carbon monoxide (DLCO) are present, but characteristics and symptoms vary with smoking exposure. OBJECTIVES: To study the prevalence of CAL, emphysema and impaired DLCO in relation to smoking and respiratory symptoms in a middle-aged population. METHODS: We investigated 28,746 randomly invited individuals (52% women) aged 50-64 years across six Swedish sites. We performed spirometry, DLCO, high-resolution computed tomography (HRCT) and asked for smoking habits and respiratory symptoms. CAL was defined as post-bronchodilator forced expiratory volume in 1 second divided by forced expiratory volume (FEV1/FVC)<0.7. RESULTS: The overall prevalence was for CAL 8.8%, for impaired DLCO (DLCO