Absolute values of lung function explain the sex difference in breathlessness in the general population

Management Reality of Female Patients with COPD: A Multicenter Cross-Sectional CAP Study in Japan

Background

Reports from Europe and North America suggest that female chronic obstructive pulmonary disease (COPD) patients have a higher symptom burden and mortality than male patients. However, little is known about the management reality of female patients with COPD in Japan.

Patients and Methods

We compared the clinical characteristics of female COPD patients with those of male using the cohort of the COPD Assessment in Practice study, which is a cross-sectional multicenter observational study.

Results

Of the 1168 patients, 133 (11.4%) were female. A history of never smoking was higher in females than males (p<0.01). Although there was no difference in age or forced expiratory volume in one second (FEV1) % predicted between the groups, modified medical research council dyspnea scale (mMRC) and number of frequent exacerbators were higher in females (mMRC≥2: p<0.01; number of exacerbations≥2: p=0.011). The mean forced vital capacity and FEV1 values in females were lower than those in males (p<0.0001 and p<0.0001, respectively). Females were more likely to use long-term oxygen therapy and inhaled corticosteroids than males (p=0.016 and p<0.01, respectively). The prevalence of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) groups B, C, D (ABCD GOLD 2017 classification), and E (ABE GOLD 2023 classification) was higher in females than in males.

Conclusion

The disease burden of female patients with COPD is higher than that of male patients in Japan, suggesting the importance of interventions considering female-dominant features such as lower absolute FVC and FEV1, respiratory failure, and asthma-like conditions.

Sex-differences in COPD: from biological mechanisms to therapeutic considerations

Chronic obstructive pulmonary disease (COPD) is a heterogeneous respiratory condition characterized by symptoms of dyspnea, cough, and sputum production. We review sex-differences in disease mechanisms, structure-function-symptom relationships, responses to therapies, and clinical outcomes in COPD with a specific focus on dyspnea. Females with COPD experience greater dyspnea and higher morbidity compared to males. Imaging studies using chest computed tomography scans have demonstrated that females with COPD tend to have smaller airways than males as well as a lower burden of emphysema. Sex-differences in lung and airway structure lead to critical respiratory mechanical constraints during exercise at a lower absolute ventilation in females compared to males, which is largely explained by sex differences in maximum ventilatory capacity. Females experience similar benefit with respect to inhaled COPD therapies, pulmonary rehabilitation, and smoking cessation compared to males. Ongoing re-assessment of potential sex-differences in COPD may offer insights into the evolution of patterns of care and clinical outcomes in COPD patients over time.

Exertional breathlessness related to medical conditions in middle-aged people: the population-based SCAPIS study of more than 25,000 men and women

BACKGROUND

Breathlessness is common in the population and can be related to a range of medical conditions. We aimed to evaluate the burden of breathlessness related to different medical conditions in a middle-aged population.

METHODS

Cross-sectional analysis of the population-based Swedish CArdioPulmonary bioImage Study of adults aged 50-64 years. Breathlessness (modified Medical Research Council [mMRC] ≥ 2) was evaluated in relation to self-reported symptoms, stress, depression; physician-diagnosed conditions; measured body mass index (BMI), spirometry, venous haemoglobin concentration, coronary artery calcification and stenosis [computer tomography (CT) angiography], and pulmonary emphysema (high-resolution CT). For each condition, the prevalence and breathlessness population attributable fraction (PAF) were calculated, overall and by sex, smoking history, and presence/absence of self-reported cardiorespiratory disease.

RESULTS

We included 25,948 people aged 57.5 ± [SD] 4.4; 51% women; 37% former and 12% current smokers; 43% overweight (BMI 25.0-29.9), 21% obese (BMI ≥ 30); 25% with respiratory disease, 14% depression, 9% cardiac disease, and 3% anemia. Breathlessness was present in 3.7%. Medical conditions most strongly related to the breathlessness prevalence were (PAF 95%CI): overweight and obesity (59.6-66.0%), stress (31.6-76.8%), respiratory disease (20.1-37.1%), depression (17.1-26.6%), cardiac disease (6.3-12.7%), anemia (0.8-3.3%), and peripheral arterial disease (0.3-0.8%). Stress was the main factor in women and current smokers.

CONCLUSION

Breathlessness mainly relates to overweight/obesity and stress and to a lesser extent to comorbidities like respiratory, depressive, and cardiac disorders among middle-aged people in a high-income setting-supporting the importance of lifestyle interventions to reduce the burden of breathlessness in the population.

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.

Dysanapsis is not associated with exertional dyspnoea in healthy male and female never-smokers aged 40 years and older

In healthy adults, airway-to-lung (i.e., dysanapsis) ratio is lower and dyspnoea during exercise at a given minute ventilation (V̇E) is higher in females than in males. We investigated the relationship between dysanapsis and sex on exertional dyspnoea in healthy adults. We hypothesized that females would have a smaller airway-to-lung ratio than males and that exertional dyspnoea would be associated with airway-to-lung ratio in males and females. We analyzed data from n = 100 healthy never-smokers aged ≥40 years enrolled in the Canadian Cohort Obstructive Lung Disease (CanCOLD) study who underwent pulmonary function testing, a chest computed tomography scan, and cardiopulmonary exercise testing. The luminal area of the trachea, right main bronchus, left main bronchus, right upper lobe, bronchus intermedius, left upper lobe, and left lower lobe were 22%-37% smaller (all p < 0.001) and the airway-to-lung ratio (i.e., average large conducting airway diameter relative to total lung capacity) was lower in females than in males (0.609 ± 0.070 vs. 0.674 ± 0.082; p < 0.001). During exercise, there was a significant effect of V̇E, sex, and their interaction on dyspnoea (all p < 0.05), indicating that dyspnoea increased as a function of V̇E to a greater extent in females than in males. However, after adjusting for age and total lung capacity, there were no significant associations between airway-to-lung ratio and measures of exertional dyspnoea, regardless of sex (all r < 0.34; all p > 0.05). Our findings suggest that sex differences in airway size do not contribute to sex differences in exertional dyspnoea.

Effects of mixed heavy metals on obstructive lung function: findings from epidemiological and toxicogenomic data

The molecular mechanisms and associations of mixed heavy metals (lead, mercury, and cadmium) on obstructive lung function (OLF) in males and females remain unknown. Here, we evaluated the interaction between the forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) ratio and three common heavy metals in males and females (n = 6221). Molecular processes involved in OLF development caused by mixed heavy metals were also identified to corroborate the earlier findings. In both males and females, as well as across the entire population, we found that serum cadmium levels were inversely related to the FEV1/FVC ratio. Interactions between serum cadmium and lead, as well as cadmium and mercury, were observed in relation to the FEV1/FVC ratio. Additionally, we observed negative correlations between the FEV1/FVC ratio and mixed serum cadmium, lead, and mercury in both men and women as well as in the overall population. Seven genes were identified as contributing to the etiology of OLF and targeted by combined heavy metals in silico analysis (CYP1A1, CRP, CXCL8, HMOX1, IL6, NOS2, and TNF). The primary relationships between these genes were co-expression interactions. The significant transcription factors and miRNAs associated with OLF and a combination of the examined heavy metals were identified as NFKB2, hsa-miR-155-5p, and hsa-miR-203a-3p. The main biological processes involved in the emergence of OLF induced by mixed heavy metals were listed as inflammatory and oxidative stress pathways, lung fibrosis, chronic obstructive pulmonary disease, as well as cytokine activity, monooxygenase activity, oxidoreductase activity, and interleukin-8 production. Threshold estimations and miRNA sponge patterns for heavy metal exposure levels associated with OLF were evaluated for both males and females. This study found that cadmium plays the most important role in the mixture of cadmium, lead, and mercury in the pathogenesis of OLF. Future studies are required to verify our findings and uncover the molecular mechanisms of long-term exposure to a variety of heavy metals, especially cadmium, in other populations, including children, adolescents, and the elderly.

Association of Metabolites, Nutrients, and Toxins in Maternal and Cord Serum with Asthma, IgE, SPT, FeNO, and Lung Function in Offspring

The role of metabolites, nutrients, and toxins (MNTs) in sera at the end of pregnancy and of their association with offspring respiratory and allergic disorders is underexplored. Untargeted approaches detecting a variety of compounds, known and unknown, are limited. In this cohort study, we first aimed at discovering associations of MNTs in grandmaternal (F0) serum with asthma, immunoglobulin E, skin prick tests, exhaled nitric oxide, and lung function parameters in their parental (F1) offspring. Second, for replication, we tested the identified associations of MNTs with disorders in their grandchildren (F2-offspring) based on F2 cord serum. The statistical analyses were sex-stratified. Using liquid chromatography/high-resolution mass spectrometry in F0, we detected signals for 2286 negative-ion lipids, 59 positive-ion lipids, and 6331 polar MNTs. Nine MNTs (one unknown MNT) discovered in F0-F1 and replicated in F2 showed higher risks of respiratory/allergic outcomes. Twelve MNTs (four unknowns) constituted a potential protection in F1 and F2. We recognized MNTs not yet considered candidates for respiratory/allergic outcomes: a phthalate plasticizer, an antihistamine, a bile acid metabolite, tryptophan metabolites, a hemiterpenoid glycoside, triacylglycerols, hypoxanthine, and polyphenol syringic acid. The findings suggest that MNTs are aspirants for clinical trials to prevent adverse respiratory/allergic outcomes.

Determinants of recovery from post-COVID-19 dyspnoea: analysis of UK prospective cohorts of hospitalised COVID-19 patients and community-based controls

Background

The risk factors for recovery from COVID-19 dyspnoea are poorly understood. We investigated determinants of recovery from dyspnoea in adults with COVID-19 and compared these to determinants of recovery from non-COVID-19 dyspnoea.

Methods

We used data from two prospective cohort studies: PHOSP-COVID (patients hospitalised between March 2020 and April 2021 with COVID-19) and COVIDENCE UK (community cohort studied over the same time period). PHOSP-COVID data were collected during hospitalisation and at 5-month and 1-year follow-up visits. COVIDENCE UK data were obtained through baseline and monthly online questionnaires. Dyspnoea was measured in both cohorts with the Medical Research Council Dyspnoea Scale. We used multivariable logistic regression to identify determinants associated with a reduction in dyspnoea between 5-month and 1-year follow-up.

Findings

We included 990 PHOSP-COVID and 3309 COVIDENCE UK participants. We observed higher odds of improvement between 5-month and 1-year follow-up among PHOSP-COVID participants who were younger (odds ratio 1.02 per year, 95% CI 1.01-1.03), male (1.54, 1.16-2.04), neither obese nor severely obese (1.82, 1.06-3.13 and 4.19, 2.14-8.19, respectively), had no pre-existing anxiety or depression (1.56, 1.09-2.22) or cardiovascular disease (1.33, 1.00-1.79), and shorter hospital admission (1.01 per day, 1.00-1.02). Similar associations were found in those recovering from non-COVID-19 dyspnoea, excluding age (and length of hospital admission).

Interpretation

Factors associated with dyspnoea recovery at 1-year post-discharge among patients hospitalised with COVID-19 were similar to those among community controls without COVID-19.

Funding

PHOSP-COVID is supported by a grant from the MRC-UK Research and Innovation and the Department of Health and Social Care through the National Institute for Health Research (NIHR) rapid response panel to tackle COVID-19. The views expressed in the publication are those of the author(s) and not necessarily those of the National Health Service (NHS), the NIHR or the Department of Health and Social Care.COVIDENCE UK is supported by the UK Research and Innovation, the National Institute for Health Research, and Barts Charity. The views expressed are those of the authors and not necessarily those of the funders.

Risk factors for impaired respiratory function post COVID-19: A prospective cohort study of nonhospitalized and hospitalized patients

BACKGROUND

Severe COVID-19 increases the risk for long-term respiratory impairment, but data after mild COVID-19 are scarce. Our aims were to determine risk factors for reduced respiratory function 3-6 months after COVID-19 infection and to investigate if reduced respiratory function would relate to impairment of exercise performance and breathlessness.

METHODS

Patients with COVID-19 were enrolled at the University Hospitals of Umeå and Örebro, and Karlstad Central Hospital, Sweden. Disease severity was defined as mild (nonhospitalized), moderate (hospitalized with or without oxygen treatment), and severe (intensive care). Spirometry, including diffusion capacity (DL_CO ), was performed 3-6 months after hospital discharge or study enrollment (for nonhospitalized patients). Breathlessness (defined as ≥1 according to the modified Medical Research Council scale) and functional exercise capacity (1-min sit-to-stand test; 1-MSTST) were assessed.

RESULTS

Between April 2020 and May 2021, 337 patients were enrolled in the study. Forced vital capacity and DL_CO were significantly lower in patients with severe COVID-19. Among hospitalized patients, 20% had reduced DL_CO , versus 4% in nonhospitalized. Breathlessness was found in 40.6% of the participants and was associated with impaired DL_CO . A pathological desaturation or heart rate response was observed in 17% of participants during the 1-MSTST. However, this response was not associated with reduced DL_CO .

CONCLUSION

Reduced DL_CO was the major respiratory impairment 3-6 months following COVID-19, with hospitalization as the most important risk factor. The lack of association between impaired DL_CO and pathological physiological responses to exertion suggests that these physiological responses are not primarily related to decreased lung function.

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.

Spirometry profiles among pregnant and non-pregnant African women: a cross-sectional study

BACKGROUND

Spirometry is a commonly used lung function test. It assesses respiratory functions by measuring the air volume and the rate at which a person can exhale from lungs filled to their total capacity. The most helpful spirometry parameters are: forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow (PEF). Pregnancy derives an altered physiological state due to hormonal and anatomical changes that affect the respiratory system. Despite that, spirometry is less commonly done during pregnancy, and if done, test results are evaluated against non-pregnancy references.

OBJECTIVE

This study aimed to explore spirometry profiles in pregnant and non-pregnant women and describe their differences.

METHODOLOGY

This cross-sectional study involved age-matched pregnant and non-pregnant participants recruited from Mnazi Moja ANC and Muhimbili University (MUHAS). A digital spirometer was used to assess respiratory function. Data were entered and analyzed using SPSS version 23. The mean spirometry values of pregnant participants were compared to those of non-pregnant participants using an independent sample t-test. A p-value of < 0.05 was considered statistically significant.

RESULTS

The study included 92 pregnant and 98 non-pregnant participants subjected to spirometry. Both FVC and FEV1 values were significantly lower in pregnant than in non-pregnant participants (2.7 ± 0.5 L vs. 2.9 ± 0.5 L; p < 0.01 and 2.2 ± 0.4 L vs. 2.5 ± 0.4 L; p < 0.01 respectively). In addition, pregnant participants had significantly lower mean PEF values than their non-pregnant counterparts (303 ± 84 L/min versus 353 ± 64 L/min; p < 0.01).

CONCLUSION

Spirometry test values are lower in pregnancy than in non-pregnant participants.

RECOMMENDATIONS

Interpreting the spirometry test values of pregnant women using references obtained from non-pregnant women may be inappropriate. Future studies should evaluate the appropriateness of predicting spirometry values of pregnant women using reference equations derived from non-pregnant women.

Prevalence, risk factors and treatments for post-COVID-19 breathlessness: a systematic review and meta-analysis

Persistent breathlessness >28 days after acute COVID-19 infection has been identified as a highly debilitating post-COVID symptom. However, the prevalence, risk factors, mechanisms and treatments for post-COVID breathlessness remain poorly understood. We systematically searched PubMed and Embase for relevant studies published from 1 January 2020 to 1 November 2021 (PROSPERO registration number: CRD42021285733) and included 119 eligible papers. Random-effects meta-analysis of 42 872 patients with COVID-19 reported in 102 papers found an overall prevalence of post-COVID breathlessness of 26% (95% CI 23-29) when measuring the presence/absence of the symptom, and 41% (95% CI 34-48) when using Medical Research Council (MRC)/modified MRC dyspnoea scale. The pooled prevalence decreased significantly from 1-6 months to 7-12 months post-infection. Post-COVID breathlessness was more common in those with severe/critical acute infection, those who were hospitalised and females, and was less likely to be reported by patients in Asia than those in Europe or North America. Multiple pathophysiological mechanisms have been proposed (including deconditioning, restrictive/obstructive airflow limitation, systemic inflammation, impaired mental health), but the body of evidence remains inconclusive. Seven cohort studies and one randomised controlled trial suggested rehabilitation exercises may reduce post-COVID breathlessness. There is an urgent need for mechanistic research and development of interventions for the prevention and treatment of post-COVID breathlessness.

Respiratory symptoms and cardiovascular causes of deaths: A population-based study with 45 years of follow-up

This study determined the association between respiratory symptoms and death from cardiovascular (CV) diseases during 45 years in a pooled sample of four cohorts of random samples of the Norwegian population with 95,704 participants. Respiratory symptoms were assessed using a modification of the MRC questionnaire on chronic bronchitis. We analyzed the association between respiratory symptoms and specific cardiovascular deaths by using Cox regression analysis with age as the time variable, accounting for cluster-specific random effects using shared frailty for study cohort. Hazard ratios (HR) for death were adjusted for sex, highest attained education, smoking habits, occupational air pollution, and birth cohort. Overall, 12,491 (13%) of participants died from CV diseases: 4,123 (33%) acute myocardial infarction, 2,326 (18%) other ischemic heart disease, 2,246 (18%) other heart diseases, 2,553 (20%) cerebrovascular diseases, and 1,120 (9%) other vascular diseases. The adjusted HR (95% confidence interval) for CV deaths was 1.9 (1.7–2.1) in men and 1.5 (1.2–1.9) in women for “yes” to the question “Are you breathless when you walk on level ground at an ordinary pace?”. The same item response showed an adjusted HR for death from acute myocardial infarction of 1.8 (1.5–2.1), other ischemic heart disease 2.2 (1.8–2.7), other heart diseases 1.5 (1.1–1.9), cerebrovascular disease 1.8 (1.5–2.3), and other circulatory diseases 1.7 (1.2–2.4). The adjusted HR for CV death was 1.3 (1.2–1.4) when answering positive to the question” Are you more breathless than people of your own age when walking uphill?”. However, positive answers to questions on cough, phlegm, wheezing and attacks of breathlessness were after adjustments not associated with early CV deaths. The associations between CV deaths and breathlessness were also present in never smokers. Self-reported breathlessness was associated with CV deaths and could be an early marker of CV deaths.

Assessment of a computed tomography-based radiomics approach for assessing lung function in lung cancer patients

PURPOSE

We aimed to assess radiomics approaches for estimating three pulmonary function test (PFT) results (forced expiratory volume in one second [FEV1], forced vital capacity [FVC], and the ratio of FEV1 to FVC [FEV₁/FVC]) using data extracted from chest computed tomography (CT) images.

METHODS

This retrospective study included 85 lung cancer patients (mean age, 75 years ±8; 69 men) who underwent stereotactic body radiotherapy between 2012 and 2020. Their pretreatment chest breath-hold CT and PFT data before radiotherapy were obtained. A total of 107 radiomics features (Shape: 14, Intensity: 18, Texture: 75) were extracted using two methods: extraction of the lung tissue (<-250 HU) (APPROACH 1), and extraction of small blood vessels and lung tissue (APPROACH 2). The PFT results were estimated using the least absolute shrinkage and selection operator regression. Pearson's correlation coefficients (r) were determined for all PFT results, and the area under the curve (AUC) was calculated for FEV₁/FVC (<70 %). Finally, we compared our approaches with the conventional formula (Conventional).

RESULTS

For the estimated FEV₁/FVC, the Pearson's r were 0.21 (P =.06), 0.69 (P <.01), and 0.73 (P <.01) for Conventional, APPROACH 1, and APPROACH 2, respectively; the AUCs for FEV₁/FVC (<70 %) were 0.67 (95 % confidence interval [CI]: 0.55, 0.79), 0.82 (CI: 0.72, 0.91; P =.047) and 0.86 (CI: 0.78, 0.94; P =.01), respectively.

CONCLUSIONS

The radiomics approach performed better than the conventional equation and may be useful for assessing lung function based on CT images.

Can birth weight predict offspring's lung function in adult age? Evidence from two Swedish birth cohorts

BACKGROUND

Associations between birth weight (BW) and adult lung function have been inconsistent and limited to early adulthood. We aimed to study this association in two population-based cohorts and explore if BW, adjusted for gestational age, predicts adult lung function. We also tested adult lung function impairment according to the mis-match hypothesis-small babies growing big as adults.

METHODS

We included 3495 individuals (aged 46.4 ± 5.4 years) from the Malmo Preventive Project (MPP), Sweden, born between 1921 and 1949, and 1401 young to middle-aged individuals (aged 28.6 ± 6.7 years) from the Malmo Offspring Study (MOS) with complete data on BW and gestational age. Adult lung function (forced vital capacity [FVC], forced expiratory volume in one second [FEV1] and the FEV1/FVC-ratio) were analysed as level of impairment (z-score), using multiple linear and logistic regressions.

RESULTS

BW (z-score) did not predict adult lung function in MPP, whereas BW was a significant (p = 0.003) predictor of FEV1 following full adjustment in MOS. For every additional unit increase in BW, children were 0.77 (95% CI 0.65-0.92) times less likely to have impaired adult lung function (FEV1). Moreover, adults born with lower BW (< 3510 g) showed improved lung function (FEV1 and FEV1/FVC in MOS and MPP, respectively) if they achieved higher adult body weight.

CONCLUSIONS

Adults born with lower birth weight, adjusted for gestational age, are more likely to have impaired lung function, seen in a younger birth cohort. Postnatal growth pattern may, however, compensate for low birth weight and contribute to better adult lung function.

Breathlessness dimensions association with physical and mental quality of life: the population based VASCOL study of elderly men

Background

Breathlessness is a multidimensional symptom prevalent in elderly affecting many aspects of life. We aimed to determine how different dimensions of breathlessness are associated with physical and mental quality of life (QoL) in elderly men.

Methods

This was a cross-sectional, population-based analysis of 672 men aged 73 years in a Swedish county. Breathlessness was assessed using Dyspnoea-12 (D-12) and Multidimensional Dyspnoea Profile (MDP), and QoL using the Short Form 12 physical and mental scores. Scores were compared as z-scores across scales and analysed using multivariable linear regression, adjusted for smoking, body mass index and the presence of respiratory and cardiovascular disease.

Results

Worse breathlessness was related to worse physical and mental QoL across all the D-12 and MDP dimension scores. Physical QoL was most strongly associated with perceptional breathlessness scores, D-12 total and physical scores (95% CI −0.45 to −0.30). Mental QoL was more strongly influenced by affective responses, MDP emotional response score (95% CI −0.61 to −0.48). Head-to-head comparison of the instruments confirmed that D-12 total and physical scores most influenced physical QoL, while mental QoL was mostly influenced by the emotional responses captured by the MDP.

Conclusion

Breathlessness dimensions and QoL measures are associated differently. Physical QoL was most closely associated with sensory and perceptual breathlessness dimensions, while emotional responses were most strongly associated with mental QoL in elderly men. D-12 and MDP contribute complimentary information, where affective and emotional responses may be related to function, deconditioning and QoL.

Underlying contributing conditions to breathlessness among middle-aged individuals in the general population: a cross-sectional study

Introduction

Breathlessness is common in the general population and associated with poorer health. Prevalence, frequencies and overlap of underlying contributing conditions among individuals reporting breathlessness in the general population is unclear. The aim was to evaluate which conditions that were prevalent, overlapping and associated with breathlessness in a middle-aged general population.

Method

Cross-sectional analysis of individuals aged 50–65 years in the Swedish CArdioPulmonary bioImage Study pilot. Data from questionnaire, spirometry testing and fitness testing were used to identify underlying contributing conditions among participants reporting breathlessness (a modified Medical Research Scale (mMRC) score ≥1). Multivariate logistic regression was used to identify independent associations with breathlessness.

Results

1097 participants were included; mean age 57.5 years, 50% women and 9.8% (n=108) reported breathlessness (mMRC ≥1). Main underlying contributing conditions were respiratory disease (57%), anxiety or depression (52%), obesity (43%) and heart disease or chest pain (35%). At least one contributing condition was found in 99.6% of all participants reporting breathlessness, while two or more conditions were present in 66%.

Conclusion

In a middle-aged general population, the main underlying contributing conditions to breathlessness were respiratory disease, anxiety or depression, obesity and heart disease or chest pain with a high level of overlap.

Breathlessness across generations: results from the RHINESSA generation study

Background

Breathlessness is a major cause of suffering and disability globally. The symptom relates to multiple factors including asthma and lung function, which are influenced by hereditary factors. No study has evaluated potential inheritance of breathlessness itself across generations.

Methods

We analysed the association between breathlessness in parents and their offspring in the Respiratory Health in Northern Europe, Spain and Australia generation study. Data on parents and offspring aged ≥18 years across 10 study centres in seven countries included demographics, self-reported breathlessness, asthma, depression, smoking, physical activity level, measured Body Mass Index and spirometry. Data were analysed using multivariable logistic regression accounting for clustering within centres and between siblings.

Results

A total of 1720 parents (mean age at assessment 36 years, 55% mothers) and 2476 offspring (mean 30 years, 55% daughters) were included. Breathlessness was reported by 809 (32.7%) parents and 363 (14.7%) offspring. Factors independently associated with breathlessness in parents and offspring included obesity, current smoking, asthma, depression, lower lung function and female sex. After adjusting for potential confounders, parents with breathlessness were more likely to have offspring with breathlessness, adjusted OR 1.8 (95% CI 1.1 to 2.9). The association was not modified by sex of the parent or offspring.

Conclusion

Parents with breathlessness were more likely to have children who developed breathlessness, after adjusting for asthma, lung function, obesity, smoking, depression and female sex in both generations. The hereditary components of breathlessness need to be further explored.

Prevalence and burden of breathlessness in Australian adults: The National Breathlessness Survey-a cross-sectional web-based population survey

BACKGROUND AND OBJECTIVE

Chronic respiratory symptoms (in particular, breathlessness and cough) can cause physical, social and emotional distress, and may indicate the presence of an underlying disease that presages future poor health outcomes. Our aim was to investigate the burden of breathlessness in Australian adults, including breathlessness that may be undiagnosed, unlabelled or untreated.

METHODS

The National Breathlessness Survey was a cross-sectional, web-based survey conducted in October 2019. Australian adults were randomly selected from a large web-based survey panel with recruitment stratified by age-group, gender and state of residence according to national population data. The main outcome measures were modified Medical Research Council (mMRC) dyspnoea scale, EuroQol visual analog scale, Dyspnoea-12 score and 4-item Patient Health Questionnaire (PHQ-4).

RESULTS

Among all respondents (n = 10,072; 51.1% female; median age group 40-49 years), 9.5% reported clinically important breathlessness (mMRC dyspnoea grade ≥ 2, 2 = 'I walk slower than people of the same age on the level because of breathlessness or have to stop for breath when walking at my own pace on the level'). Among those with clinically important breathlessness, 49.1% rated their general health as fair or poor and 44.2% had at least moderate depression or anxiety symptoms (PHQ ≥ 6) but over half (50.8%) did not report a current respiratory or heart condition diagnosis.

CONCLUSION

Breathlessness is common among Australian adults, and is associated with a substantial burden of ill health, including among people without a diagnosed respiratory or heart condition. The extent of underdiagnosis of these conditions or alternative causes of breathlessness requires further investigation.

An integrative approach to the pulmonary physiology of exercise: when does biological sex matter?

Historically, many studies investigating the pulmonary physiology of exercise (and biomedical research in general) were performed exclusively or predominantly with male research participants. This has led to an incomplete understanding of the pulmonary response to exercise. More recently, important sex-based differences with respect to the human respiratory system have been identified. The purpose of this review is to summarize current findings related to sex-based differences in the pulmonary physiology of exercise. To that end, we will discuss how morphological sex-based differences of the respiratory system affect the respiratory response to exercise. Moreover, we will discuss sex-based differences of the physiological integrative responses to exercise, and how all these differences can influence the regulation of breathing. We end with a brief discussion of pregnancy and menopause and the accompanying ventilatory changes observed during exercise.

Dyspnoea and symptom burden in mild-moderate COPD: the Canadian Cohort Obstructive Lung Disease Study

Studies assessing dyspnoea and health-related quality of life (HRQoL) in chronic obstructive pulmonary disease (COPD) have focussed on patients in clinical settings, not the general population.

The aim of this analysis was to compare the prevalence and severity of dyspnoea and impaired HRQoL in individuals with and without COPD from the general population, focussing on mild–moderate COPD.

Analysis of the 3-year Canadian Cohort Obstructive Lung Disease (CanCOLD) study included four subgroups: mild COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1); moderate COPD (GOLD 2); non-COPD smokers; and non-COPD never-smokers. The primary outcome was dyspnoea (Medical Research Council (MRC) scale), and the secondary outcome was HRQoL (COPD Assessment Test (CAT) score; Saint George's Respiratory Questionnaire (SGRQ) score). Subgroups were analysed by sex, physician-diagnosed COPD status and exacerbations.

1443 participants (mild COPD (n=397); moderate COPD (n=262(; smokers (n=449) and never-smokers (n=335)) were studied. People with mild COPD were more likely to report more severe dyspnoea (MRC 2 versus 1) than those without COPD (OR (95% CI) 1.42 (1.05–1.91)), and non-COPD never-smokers (OR (95%CI) 1.64 (1.07–2.52)). Among people with mild COPD, more severe dyspnoea was reported in women versus men (MRC2 versus 1; OR (95% CI) 3.70 (2.23–6.14)); people with, versus without, physician-diagnosed COPD (MRC2 versus 1; OR (95% CI) 3.27 (1.71–6.23)), and people with versus without recent exacerbations (MRC2 versus 1; ≥2 versus 0 exacerbations: OR (95% CI) 3.62 (1.02–12.86); MRC ≥3 versus 1; 1 versus 0 exacerbation: OR (95% CI): 9.24 (2.01–42.42)). Similar between-group differences were obtained for CAT and SGRQ scores.

Careful assessment of dyspnoea and HRQoL could help identify individuals for earlier diagnosis and treatment.

Individuals from a population-based study with mild COPD are more symptomatic than non-COPD peers. Worse dyspnoea and quality of life was reported by people with mild COPD who are female, or have a physician diagnosis of COPD or recent exacerbations.https://bit.ly/2XE2B6S

High prevalence of exercise-induced stridor during Parkrun: a cross-sectional field-based evaluation

BACKGROUND AND OBJECTIVE

The differential diagnosis for exercise-associated breathlessness is broad, however, when a young athletic individual presents with respiratory symptoms, they are most often prescribed inhaler therapy for presumed exercise-induced asthma (EIA). The purpose of this study was therefore to use a novel sound-based approach to assessment to evaluate the prevalence of exertional respiratory symptoms and characterise abnormal breathing sounds in a large cohort of recreationally active individuals.

METHODS

Cross-sectional field-based evaluation of individuals completing Parkrun. PHASE 1: Prerace, clinical assessment and baseline spirometry were conducted. At peak exercise and immediately postrace, breathing was monitored continuously using a smartphone. Recordings were analysed retrospectively and coded for signs of the predominant respiratory noise. PHASE 2: A subpopulation that reported symptoms with at least one audible sign of respiratory dysfunction was randomly selected and invited to attend the laboratory on a separate occasion to undergo objective clinical workup to confirm or refute EIA.

RESULTS

Forty-eight participants (22.6%) had at least one audible sign of respiratory dysfunction; inspiratory stridor (9.9%), expiratory wheeze (3.3%), combined stridor+wheeze (3.3%), cough (6.1%). Over one-third of the cohort (38.2%) were classified as symptomatic. Ten individuals attended a follow-up appointment, however, only one had objective evidence of EIA.

CONCLUSIONS

The most common audible sign, detected in approximately 1 in 10 individuals, was inspiratory stridor, a characteristic feature of upper airway closure occurring during exercise. Further work is now required to further validate the precision and feasibility of this diagnostic approach in cohorts reporting exertional breathing difficulty.

Openness Personality Trait Associated With Benefit From a Nonpharmacological Breathlessness Intervention in People With Intrathoracic Cancer: An Exploratory Analysis

CONTEXT

Breathlessness is common in people with lung cancer. Nonpharmacological breathlessness interventions reduce distress because of and increase mastery over breathlessness.

OBJECTIVES

Identify patient characteristics associated with response to breathlessness interventions.

METHODS

Exploratory secondary trial data analysis. Response defined as a one-point improvement in 0-10 Numerical Rating Scale of worst breathlessness/last 24 hours (response-worst) or a 0.5-point improvement in the Chronic Respiratory Questionnaire (CRQ) mastery (response-mastery) at four weeks. Univariable regression explored relationships with plausible demographic, clinical, and psychological variables followed by multivariable regression for associated (P < 0.05) variables.

RESULTS

About 158 participants with intrathoracic cancer (mean age 69.4 [SD 9.35] years; 40% women) were randomized to one or three breathlessness training sessions. About 91 participants had evaluable data for response-worst and 107 for response-mastery. In the univariable analyses, the personality trait openness was associated with response-worst (odds ratio [OR] 1.99 [95% CI 1.08-3.67]; P = 0.028) and response-mastery (OR 1.84 [95% CI 1.04-3.23]; P = 0.035). Higher CRQ-fatigue (OR 0.61 [95% CI 0.41-0.91]; P = 0.015), CRQ-emotion (OR 0.68 [95% CI 0.47-0.96]; P = 0.030), and worse CRQ-mastery (OR 0.61 [95% CI 0.42-0.88]; P = 0.008), and the presence of metastases and fatigue were associated with reduced odds of response-mastery. In the adjusted response-mastery model, only openness remained (OR 1.73 [95% CI 0.95-3.15]; P = 0.072).

CONCLUSION

Worse baseline health, worse breathlessness mastery, but not severity, and openness were associated with a better odds of response. Breathlessness services must be easy to access, and patients should be encouraged and supported to attend.

Differences between experienced and recalled breathlessness: a review

PURPOSE OF REVIEW

Experienced breathlessness and recalled breathlessness are two different entities, which may be associated with different factors and might have different impacts on function for the individual. The aim was to review the knowledge from the last 2 years concerning experienced breathlessness and recalled breathlessness and related factors.

RECENT FINDINGS

Experienced breathlessness was most often induced or measured during exercise testing in a lab environment using a modified Borg scale. It was associated with both psychological factors, such as social rejection, presence of others, psychosocial stress and prenatal exposure to stress, as well as physical factors, such as hypoxia and frequent exacerbations.Recalled breathlessness was most often measured in epidemiological studies, most commonly using the modified Medical Research Council scale. It was associated with lung volumes, overweight, exercise training, frailty, smoking, personality traits, behavior and marital and occupational status.

SUMMARY

No studies during the review period had directly compared experienced breathlessness and recalled breathlessness. Several factors were related to either experienced breathlessness or recalled breathlessness but no clear differences between factors were found in this review. There is a need for comparative studies using the same measurement methods and in the same settings in order to examine their relation.

The association of body mass index, weight gain and central obesity with activity-related breathlessness: the Swedish Cardiopulmonary Bioimage Study

Introduction

Breathlessness is common in the population, especially in women and associated with adverse health outcomes. Obesity (body mass index (BMI) >30 kg/m2) is rapidly increasing globally and its impact on breathlessness is unclear.

Methods

This population-based study aimed primarily to evaluate the association of current BMI and self-reported change in BMI since age 20 with breathlessness (modified Research Council score ≥1) in the middle-aged population. Secondary aims were to evaluate factors that contribute to breathlessness in obesity, including the interaction with spirometric lung volume and sex.

Results

We included 13 437 individuals; mean age 57.5 years; 52.5% women; mean BMI 26.8 (SD 4.3); mean BMI increase since age 20 was 5.0 kg/m2; and 1283 (9.6%) reported breathlessness. Obesity was strongly associated with increased breathlessness, OR 3.54 (95% CI, 3.03 to 4.13) independent of age, sex, smoking, airflow obstruction, exercise level and the presence of comorbidities. The association between BMI and breathlessness was modified by lung volume; the increase in breathlessness prevalence with higher BMI was steeper for individuals with lower forced vital capacity (FVC). The higher breathlessness prevalence in obese women than men (27.4% vs 12.5%; p<0.001) was related to their lower FVC. Irrespective of current BMI and confounders, individuals who had increased in BMI since age 20 had more breathlessness.

Conclusion

Breathlessness is independently associated with obesity and with weight gain in adult life, and the association is stronger for individuals with lower lung volumes.

Association of Symptoms of Obstructive Lung Disease and All-Cause Mortality in Older Adult Smokers

OBJECTIVES

This study aims to investigate the impact of respiratory symptoms in current and former smokers with and without obstructive lung disease (OLD) on all-cause mortality.

DESIGN

Secondary analysis in a prospective cohort (the Health, Aging and Body Composition study).

SETTING

Memphis, Tennessee, and Pittsburgh, Pennsylvania.

PARTICIPANTS

Black and white men and women with a history of current and former smoking (N = 596; 63% male and 37% female) aged 70-79 years followed for 13 years. Participants were categorized into 4 mutually exclusive groups based on symptom profile and forced expiratory volume in the 1st second to forced vital capacity ratio. The groups were Less Dyspnea-No OLD (N = 196), More Dyspnea-No OLD (N = 104), Less Dyspnea-With OLD (N = 162), and More Dyspnea-With OLD (N = 134).

MEASUREMENTS

All-cause mortality.

RESULTS

Overall, 53% in Less Dyspnea-No OLD, 63% in More Dyspnea-No OLD, 67% in Less Dyspnea-With OLD, and 84% in More Dyspnea-With OLD died within the 13- year follow up period (log-rank χ²  = 44.4, P < .0001). The hazard ratio was highest for participants with OLD, both with (HR =1.91, 95% CI 1.44 - 2.54; P < .0001) and without dyspnea (HR = 1.52, 95% CI 1.15 - 2.02; p = .004). Participants without OLD but with dyspnea had a similar risk of death to subjects who had OLD but fewer symptoms.

CONCLUSIONS

OLD is associated with high risk of death with different risk profiles based on symptom group. Patients with symptoms of shortness of breath without OLD should be considered an at-risk group given their similar mortality to those with OLD with minimal symptoms. J Am Geriatr Soc 67:2116-2122, 2019.

Increased prevalence of exercise-induced airway symptoms - A five-year follow-up from adolescence to young adulthood

BACKGROUND

Exercise-induced airway symptoms are common in adolescents. Little is known about the development of symptoms from adolescence to early adulthood. Therefore, we studied the prevalence, incidence, and remission of exercise-induced airway symptoms (including wheeze, cough, chest and throat tightness, hoarseness, and stridor) in adolescents, over a five-year period.

METHODS

In 2011, all adolescents aged 12-13 years in Uppsala (n = 3 838) were invited to answer a questionnaire on exercise-induced airway symptoms. All responding adolescents (n = 2 309) were invited to answer the same questionnaire again after five years. In total, 1 002 adolescents responded (43.4%).

RESULTS

The prevalence of exercise-induced airway symptoms increased from 25% at baseline to 49% at follow-up (p < 0.001). More females than males reported symptoms at both time points. The incidence of airway symptoms was 42.2%, with no sex differences. More males than females reported symptom remission (20.2 vs. 10.7%, p < 0.001). Females reported a higher asthma prevalence at follow-up than at baseline (7.6 vs. 15.2%), while males did not (10.9 vs. 8.0%), leading to a sex difference in prevalence at follow-up (p < 0.001). Smoking and baseline respiratory symptoms were associated with an increased risk of reporting symptoms at follow-up.

CONCLUSIONS

A twofold increase in the prevalence of exercise-induced airway symptoms over a five-year period was found in this cohort. Females were more likely to report symptoms at both time points. Knowledge of these age-related changes in symptoms and their association to female gender is useful for future studies and healthcare providers.

Agreement Between Breathlessness Severity and Unpleasantness in People With Chronic Breathlessness: A Longitudinal Clinical Study

CONTEXT

Chronic breathlessness is a cardinal symptom in cardiopulmonary disease where both overall intensity or severity (S) and unpleasantness (U) are commonly quantified.

OBJECTIVE

We aimed to evaluate agreement between breathlessness severity and unpleasantness over eight days in patients with chronic breathlessness.

METHODS

Longitudinal analysis of 265 patients with chronic breathlessness who rated current overall breathlessness severity and unpleasantness on a 0-100 mm visual analogue scale (VAS) in the morning and evening over eight days. A total of 3630 paired overall severity-unpleasantness (S-U) differences were analyzed; median 15 (IQR 13-16) per patient. Agreement was evaluated using Bland-Altman plots. Associations of the difference between severity and unpleasantness (S-U difference) with clinical factors and perceived quality of life were analyzed using multilevel linear regression adjusted for confounders.

RESULTS

Over eight days, severity and unpleasantness scores were highly correlated, had similar variability, and varied more between patients than within patients. The mean S-U difference was small at 2.1 mm. Agreement between overall severity and unpleasantness was similar or higher than expected from the variability in individual scores. The S-U difference was similar across evaluated factors including age, sex, diagnosis, morning/evening assessment, modified Medical Research Council breathlessness score, morphine treatment, and presence of different sensory qualities of breathlessness. Higher overall severity and unpleasantness associated with worse perceived quality of life in a similar way.

CONCLUSION

In patients with chronic breathlessness over eight days, overall severity and unpleasantness of breathlessness were comparable and associated to other clinical factors in a similar manner.

Manipulation of mechanical ventilatory constraint during moderate intensity exercise does not influence dyspnoea in healthy older men and women

KEY POINTS

The perceived intensity of exertional breathlessness (i.e. dyspnoea) is higher in older women than in older men, possibly as a result of sex-differences in respiratory system morphology. During exercise at a given absolute intensity or minute ventilation, older women have a greater degree of mechanical ventilatory constraint (i.e. work of breathing and expiratory flow limitation) than their male counterparts, which may lead to a greater perceived intensity of dyspnoea. Using a single-blind randomized study design, we experimentally manipulated the magnitude of mechanical ventilatory constraint during moderate-intensity exercise at ventilatory threshold in healthy older men and women. We found that changes in the magnitude of mechanical ventilatory constraint within the physiological range had no effect on dyspnoea in healthy older adults. When older men and women perform moderate intensity exercise, mechanical ventilatory constraint does not contribute significantly to the sensation of dyspnoea.

ABSTRACT

We aimed to determine the effect of manipulating mechanical ventilatory constraint during submaximal exercise on dyspnoea in older men and women. Eighteen healthy subjects (aged 60-80 years; nine men and nine women) completed two days of testing. On day 1, subjects were assessed for pulmonary function and performed a maximal incremental cycle exercise test. On day 2, subjects performed three 6-min bouts of cycling at ventilatory threshold, in a single-blind randomized manner, while breathing: (i) normoxic helium-oxygen (HEL) to reduce the work of breathing (W_b ) and alleviate expiratory flow limitation (EFL); (ii) through an inspiratory resistance (RES) of ∼5 cmH₂ O L^-1  s^-1 to increase W_b ; and (iii) ambient air as a control (CON). Oesophageal pressure, diaphragm electromyography, and sensory responses (category-ratio 10 Borg scale) were monitored throughout exercise. During the HEL condition, there was a significant decrease in W_b (men: -21 ± 6%, women: -17 ± 10%) relative to CON (both P < 0.01). Moreover, if EFL was present during CON (four men and five women), it was alleviated during HEL. Conversely, during the RES condition, W_b (men: 42 ± 19%, women: 50 ± 16%) significantly increased relative to CON (both P < 0.01). There was no main effect of sex on W_b (P = 0.59). Across conditions, women reported significantly higher dyspnoea intensity than men (2.9 ± 0.9 vs. 1.9 ± 0.8 Borg scale units, P < 0.05). Despite significant differences in the degree of mechanical ventilatory constraint between conditions, the intensity of dyspnoea was unaffected, independent of sex (P = 0.46). When older men and women perform moderate intensity exercise, mechanical ventilatory constraint does not contribute significantly to the sensation of dyspnoea.

Absolute lung size and the sex difference in breathlessness in the general population

Background

Breathlessness is associated with major adverse health outcomes and is twice as common in women as men in the general population. We evaluated whether this is related to their lower absolute lung volumes.

Methods

Cross-sectional analysis of the population-based Swedish CardioPulmonarybioImage Study (SCAPIS) Pilot, including static spirometry and diffusing capacity (n = 1,013; 49% women). Breathlessness was measured using the modified Medical Research Council (mMRC) scale and analyzed using ordinal logistic regression adjusting for age, pack-years of smoking, body mass index, chronic airway limitation, asthma, chronic bronchitis, depression and anxiety in all models.

Results

Breathlessness was twice as common in women as in men; adjusted odds ratio (OR) 2.20 (95% confidence interval, 1.32−3.66). Lower absolute lung volumes were associated with increased breathlessness prevalence in both men and women. The sex difference in breathlessness was unchanged when adjusting for lung function in %predicted, but disappeared when controlling for absolute values of total lung capacity (OR 1.12; 0.59−2.15), inspiratory capacity (OR 1.26; 0.68−2.35), forced vital capacity (OR 0.84; 0.42−1.66), forced expiratory volume in one second (OR 0.70; 0.36−1.35) or lung diffusing capacity (OR 1.07; 0.58−1.97).

Conclusion

In the general population, the markedly higher prevalence of breathlessness in women is related to their smaller absolute lung volumes.

Unemployment in chronic airflow obstruction around the world: results from the BOLD study

We aimed to examine associations between chronic airflow obstruction (CAO) and unemployment across the world.

Cross-sectional data from 26 sites in the Burden of Obstructive Lung Disease (BOLD) study were used to analyse effects of CAO on unemployment. Odds ratios for unemployment in subjects aged 40–65 years were estimated using a multilevel mixed-effects generalised linear model with study site as random effect. Site-by-site heterogeneity was assessed using individual participant data meta-analyses.

Out of 18 710 participants, 11.3% had CAO. The ratio of unemployed subjects with CAO divided by subjects without CAO showed large site discrepancies, although these were no longer significant after adjusting for age, sex, smoking and education. The site-adjusted odds ratio (95% CI) for unemployment was 1.79 (1.41–2.27) for CAO cases, decreasing to 1.43 (1.14–1.79) after adjusting for sociodemographic factors, comorbidities and forced vital capacity. Of other covariates that were associated with unemployment, age and education were important risk factors in high-income sites (4.02 (3.53–4.57) and 3.86 (2.80–5.30), respectively), while female sex was important in low- to middle-income sites (3.23 (2.66–3.91)).

In the global BOLD study, CAO was associated with increased levels of unemployment, even after adjusting for sociodemographic factors, comorbidities and lung function.

Chronic airflow obstruction increases risk of unemployment, and is a burden to welfare systems worldwidehttp://ow.ly/cxzv30cQ17A