Estimating population prevalence of potential airflow obstruction using different spirometric criteria: a pooled cross-sectional analysis of persons aged 40-95 years in England and Wales

Predicting parameters of airway dynamics generated from inspiratory and expiratory plethysmographic airway loops, differentiating subtypes of chronic obstructive diseases

BACKGROUND

The plethysmographic shift volume-flow loop (sRaw-loop) measured during tidal breathing allows the determination of several lung function parameters such as the effective specific airway resistance (sReff), calculated from the ratio of the integral of the resistive aerodynamic specific work of breathing (sWOB) and the integral of the corresponding flow-volume loop. However, computing the inspiratory and expiratory areas of the sRaw-loop separately permits the determination of further parameters of airway dynamics. Therefore, we aimed to define the discriminating diagnostic power of the inspiratory and expiratory sWOB (sWOBin, sWOBex), as well as of the inspiratory and expiratory sReff (sReff IN and sReff EX), for discriminating different functional phenotypes of chronic obstructive lung diseases.

METHODS

Reference equations were obtained from measurement of different databases, incorporating 194 healthy subjects (35 children and 159 adults), and applied to a collective of 294 patients with chronic lung diseases (16 children with asthma, aged 6-16 years, and 278 adults, aged 17-92 years). For all measurements, the same type of plethysmograph was used (Jaeger Würzburg, Germany).

RESULTS

By multilinear modelling, reference equations of sWOBin, sWOBex, sReff IN and sReff EX were derived. Apart from anthropometric indices, additional parameters such as tidal volume (VT), the respiratory drive (P0.1), measured by means of a mouth occlusion pressure measurement 100 ms after inspiration and the mean inspiratory flow (VT/TI) were found to be informative. The statistical approach to define reference equations for parameters of airway dynamics reveals the interrelationship between covariants of the actual breathing pattern and the control of breathing.

CONCLUSIONS

We discovered that sWOBin, sWOBex, sReff IN and sReff EX are new discriminating target parameters, that differentiate much better between chronic obstructive diseases and their subtypes, especially between chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap (ACO), thus strengthening the concept of precision medicine.

Prevalence and characterisation of exercise-induced laryngeal obstruction in patients with exercise-induced dyspnoea

OBJECTIVE

The prevalence of exercise-induced laryngeal obstruction is largely unknown. This study aimed to evaluate the prevalence of this condition in a selected study population of patients with exercise-induced dyspnoea.

METHOD

A retrospective analysis was conducted of demographic data, co-morbidities, medication, symptoms, performance level of sporting activities, continuous laryngoscopy exercise test results and subsequent treatment.

RESULTS

Data from 184 patients were analysed. The overall prevalence of exercise-induced laryngeal obstruction in the study population was 40 per cent, and the highest prevalence was among females aged under 18 years (61 per cent). However, a high prevalence among males aged under 18 years (50 per cent) and among adults regardless of gender (34 per cent) was also found.

CONCLUSION

The prevalence of exercise-induced laryngeal obstruction is clinically relevant regardless of age and gender. Clinicians are encouraged to consider exercise-induced laryngeal obstruction as a possible diagnosis in patients suffering from exercise-induced respiratory symptoms. No single characteristic that can distinguish exercise-induced laryngeal obstruction from other similar conditions was identified.

Association between occupational exposure and chronic obstructive pulmonary disease and respiratory symptoms in the Spanish population

INTRODUCTION

The aim of this study was to analyze the impact of occupational exposure on chronic obstructive pulmonary disease (COPD) and respiratory symptoms in the general Spanish population.

METHODS

This was a study nested in the Spanish EPISCAN II cross-sectional epidemiological study that included participants who had completed a structured questionnaire on their occupational history, a questionnaire on respiratory symptoms, and forced spirometry. The data were analyzed using Chi-square and Student's t tests and adjusted models of multiple linear regression and logistic regression.

RESULTS

We studied 7502 subjects, 51.1% women, with a mean age of 60±11 years. Overall, 53.2% reported some respiratory symptoms, 7.9% had respiratory symptoms during their work activity, 54.2% were or had been smokers, and 11.3% (851 subjects) met COPD criteria on spirometry. A total of 3056 subjects (40.7%) reported exposure to vapors, gases, dust or fumes (VGDF); occupational exposure to VGDF was independently associated with the presence of COPD (OR 1.22, 95% CI: 1.03-1.44), respiratory symptoms (OR 1.45, 95%: CI 1.30-1.61), and respiratory symptoms at work (OR 4.69, 95% CI: 3.82-5.77), with a population attributable fraction for COPD of 8.2%.

CONCLUSIONS

Occupational exposure is associated with a higher risk of COPD and respiratory symptoms in the Spanish population. These results highlight the need to follow strict prevention measures to protect the respiratory health of workers.

Functional Predictors Discriminating Asthma-COPD Overlap (ACO) from Chronic Obstructive Pulmonary Disease (COPD)

Background

A significant proportion of patients with obstructive lung disease have clinical and functional features of both asthma and chronic obstructive pulmonary disease (COPD), referred to as the asthma–COPD overlap (ACO). The distinction of these phenotypes, however, is not yet well-established due to the lack of defining clinical and/or functional criteria. The aim of our investigations was to assess the discriminating power of various lung function parameters on the assessment of ACO.

Methods

From databases of 4 pulmonary centers, a total of 540 patients (231 males, 309 females), including 372 patients with asthma, 77 patients with ACO and 91 patients with COPD, were retrospectively collected, and gradients among combinations of explanatory variables of spirometric (FEV₁, FEV₁/FVC, FEF_25-75), plethysmographic (sR_eff, sG_eff, the aerodynamic work of breathing at rest; sWOB), static lung volumes, including trapped gases and measurements of the carbon monoxide transfer (DL_CO, K_CO) were explored using multiple factor analysis (MFA). The discriminating power of lung function parameters with respect to ACO was assessed using linear discriminant analysis (LDA).

Results

LDA revealed that parameters of airway dynamics (sWOB, sR_eff, sG_eff) combined with parameters of static lung volumes such as functional residual capacity (FRC_pleth) and trapped gas at FRC (V_TG^FRC) are valuable and potentially important tools discriminating between asthma, ACO and COPD. Moreover, sWOB significantly contributes to the diagnosis of obstructive airway diseases, independent from the state of pulmonary hyperinflation, whilst the diffusion capacity for carbon monoxide (DL_CO) significantly differentiates between the 3 diagnostic classes.

Conclusion

The complexity of COPD with its components of interaction and their heterogeneity, especially in discrimination from ACO, may well be differentiated if patients are explored by a whole set of target parameters evaluating, interactionally, flow limitation, airway dynamics, pulmonary hyperinflation, small airways dysfunction and gas exchange disturbances assessing specific functional deficits.

ARTP statement on pulmonary function testing 2020

The Association for Respiratory Technology & Physiology (ARTP) last produced a statement on the performance of lung function testing in 1994. At that time the focus was on a practical statement for people working in lung function laboratories. Since that time there have been many technological advances and alterations to best practice in the measurement and interpretation of lung function assessments. In light of these advances an update was warranted. ARTP, therefore, have provided within this document, where available, the most up-to-date and evidence-based recommendations for the most common lung function assessments performed in laboratories across the UK. These recommendations set out the requirements and considerations that need to be made in terms of environmental and patient factors that may influence both the performance and interpretation of lung function tests. They also incorporate procedures to ensure quality assured diagnostic investigations that include those associated with equipment, the healthcare professional conducting the assessments and the results achieved by the subject. Each section aims to outline the common parameters provided for each investigation, a brief principle behind the measurements (where applicable), and suggested acceptability and reproducibility criteria.

Targeted therapy in eosinophilic chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common and preventable airway disease causing significant worldwide mortality and morbidity. Lifetime exposure to tobacco smoking and environmental particles are the two major risk factors. Over recent decades, COPD has become a growing public health problem with an increase in incidence. COPD is defined by airflow limitation due to airway inflammation and small airway remodelling coupled to parenchymal lung destruction. Most patients exhibit neutrophil-predominant airway inflammation combined with an increase in macrophages and CD8⁺ T-cells. Asthma is a heterogeneous chronic inflammatory airway disease. The most studied subtype is type 2 (T2) high eosinophilic asthma, for which there are an increasing number of biologic agents developed. However, both asthma and COPD are complex and share common pathophysiological mechanisms. They are known as overlapping syndromes as approximately 40% of patients with COPD present an eosinophilic airway inflammation. Several studies suggest a putative role of eosinophilia in lung function decline and COPD exacerbation. Recently, pharmacological agents targeting eosinophilic traits in uncontrolled eosinophilic asthma, especially monoclonal antibodies directed against interleukins (IL-5, IL-4, IL-13) or their receptors, have shown promising results. This review examines data on the rationale for such biological agents and assesses efficacy in T2-endotype COPD patients.

Patients with severe COPD and eosinophilic inflammation experience uncontrolled symptoms despite optimal pharmaceutical treatment. The development of new biomarkers is needed for better phenotyping of patients to propose innovative targeted therapy.https://bit.ly/2KzWuNO

Chronic Obstructive Pulmonary Disease and Breathlessness in Older Workers Predict Economic Inactivity. A Prospective Cohort Study

Rationale: There is an aspiration to retain increasing numbers of older workers in employment, and strategies to achieve this need to make provision for the increasing prevalence of chronic diseases with age. There is a consistent body of cross-sectional evidence that suggests that patients with chronic obstructive pulmonary disease are more likely to have adverse employment outcomes.Objectives: We report the findings of the first longitudinal study of this issue.Methods: We recruited full-time employed men and women in their 50s and followed them for a period of 18 months; we examined, after adjustment for potential confounders, the associations between breathlessness and airway obstruction at baseline and loss of employment in the intervening period.Measurements and Main Results: Among participants responding to the follow-up questionnaire (1,656 of 1,773 [93%]), the majority (78.5%) continued in full-time employment, but 10.6% were in part-time employment and 10.9% were no longer in paid employment. The adjusted risk of loss of employment was significantly increased for those with moderate or severe chronic obstructive pulmonary disease (risk ratio, 2.89; 95% confidence interval, 1.80-4.65) or breathlessness (risk ratio, 3.07; 95% confidence interval, 2.16-4.37) at baseline. There was no evident modification by sex or by manual/nonmanual work.Conclusions: Airway obstruction and breathlessness are independently associated with premature loss from the workforce in older workers; these observations provide strong support to the available cross-sectional evidence and suggest that interventions to help those with chronic obstructive pulmonary disease who wish to remain in work need to be tested.

The Occupational Burden of Nonmalignant Respiratory Diseases. An Official American Thoracic Society and European Respiratory Society Statement

Rationale: Workplace inhalational hazards remain common worldwide, even though they are ameliorable. Previous American Thoracic Society documents have assessed the contribution of workplace exposures to asthma and chronic obstructive pulmonary disease on a population level, but not to other chronic respiratory diseases. The goal of this document is to report an in-depth literature review and data synthesis of the occupational contribution to the burden of the major nonmalignant respiratory diseases, including airway diseases; interstitial fibrosis; hypersensitivity pneumonitis; other noninfectious granulomatous lung diseases, including sarcoidosis; and selected respiratory infections. Methods: Relevant literature was identified for each respiratory condition. The occupational population attributable fraction (PAF) was estimated for those conditions for which there were sufficient population-based studies to allow pooled estimates. For the other conditions, the occupational burden of disease was estimated on the basis of attribution in case series, incidence rate ratios, or attributable fraction within an exposed group. Results: Workplace exposures contribute substantially to the burden of multiple chronic respiratory diseases, including asthma (PAF, 16%); chronic obstructive pulmonary disease (PAF, 14%); chronic bronchitis (PAF, 13%); idiopathic pulmonary fibrosis (PAF, 26%); hypersensitivity pneumonitis (occupational burden, 19%); other granulomatous diseases, including sarcoidosis (occupational burden, 30%); pulmonary alveolar proteinosis (occupational burden, 29%); tuberculosis (occupational burden, 2.3% in silica-exposed workers and 1% in healthcare workers); and community-acquired pneumonia in working-age adults (PAF, 10%). Conclusions: Workplace exposures contribute to the burden of disease across a range of nonmalignant lung conditions in adults (in addition to the 100% burden for the classic occupational pneumoconioses). This burden has important clinical, research, and policy implications. There is a pressing need to improve clinical recognition and public health awareness of the contribution of occupational factors across a range of nonmalignant respiratory diseases.

Clinical characteristics of patients newly diagnosed with COPD by the fixed ratio and lower limit of normal criteria: a cross-sectional analysis of the TargetCOPD trial

Background

Consensus on the definition of airflow obstruction to diagnose COPD remains unresolved.

Methods

We undertook systematic case finding for COPD in primary care using the fixed ratio (FR) criterion (forced expiratory volume in 1 s/forced vital capacity [FEV1/FVC] <0.7) for defining airflow obstruction and also using the lower limit of normal (LLN). We then compared the clinical characteristics of those identified by the 2 criteria.

Results

A total of 3,721 individuals reporting respiratory symptoms were invited for spirometry. A total of 2,607 attended (mean age 60.4 years, 52.8% male, 29.8% current smokers) and 32.6% had airflow obstruction by FR ("FR+") and 20.2% by LLN ("LLN+"). Compared with the LLN+/FR+ group, the LLN-/FR+ group (12.4%) was significantly older, had higher FEV1 and FEV1/FVC, lower COPD assessment test scores, and less cough, sputum, and wheeze, but was significantly more likely to report a diagnosis of heart disease (14.2% versus 6.9%, p<0.001). Compared with the LLN+/FR+ group, the LLN-/FR- group was younger, had a higher body mass index, fewer pack-years, a lower prevalence of respiratory symptoms except for dyspnea, and lower FVC and higher FEV1. The probability of known heart disease was significantly lower in the LLN+/FR+ group compared with those with preserved lung function (LLN-/FR-) (adjusted odds ratio 0.62, 95% CI: 0.43-0.90) but this was not seen in the LLN-/FR+ group (adjusted odds ratio 0.90, 95% CI: 0.63-1.29).

Conclusion

In symptomatic individuals, defining airflow obstruction by FR instead of LLN identifies a significant number of individuals who have less respiratory and more cardiac clinical characteristics.

Prevalence of Airflow Limitation Defined by Pre- and Post-Bronchodilator Spirometry in a Community-Based Health Checkup: The Hisayama Study

Spirometry in health checkup may contribute to early diagnosis of chronic obstructive pulmonary disease (COPD) and asthma. Although post-bronchodilator airflow limitation is essential for definite diagnosis of COPD and post-bronchodilator normalization of airflow is suggestive of asthma, this test has not been prevailed in health checkup. The objective of this study was to estimate the prevalence of airflow limitation defined by pre- and post-bronchodilator spirometry in health checkup. Post-bronchodilator spirometry was conducted for participants with airflow limitation in a town-wide health checkup for residents aged 40 years and older in Hisayama, a town in the western part of Japan. The prevalence of pre- and post-bronchodilator airway limitation defined by FEV1/FVC < 70% were estimated. A total of 2,232 participants underwent pre-bronchodilator spirometry. In males, the age of current smokers was significantly younger than those of never smokers and former smokers. In females, the ages of current- and former smokers were significantly younger than never smokers. The values of %FEV1 and %FVC in current smokers were significantly lower than those in former smokers and never smokers. Two hundred sixty nine subjects, 85% of total subjects with a pre-bronchodilator FEV1/FVC < 70%, completed post-bronchodilator spirometry. The prevalence of pre-bronchodilator airflow limitation was 14.6% in males and 13.7% in females, and the prevalence of post-bronchodilator airway limitation was 8.7% and 8.7%, respectively. Post-bronchodilator spirometry in health checkup would reduce the number of subjects with probable COPD to two-third. Recommendation for those examinees to take further evaluations may pave the way for early intervention.

GOLD criteria overestimate airflow limitation in one-third of cases in the general Finnish population

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) diagnostic criteria for chronic obstructive pulmonary disease (COPD) use a fixed threshold of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio (<0.70) in post-bronchodilation spirometry to indicate disease, which has been shown to underestimate and overestimate disease prevalence in younger and older adults, respectively, whilst criteria based on reference values have better accuracy. Differences in reference values have limited their use in international studies. However, the new Global Lung Function Initiative reference values (GLI2012) showed FEV1/FVC to be the least dependent on ethnicity. The aim of this study was to assess the prevalence of airflow limitation with GLI2012 and the degree of underdetection or overestimation related to the use of GOLD in the general population. A Finnish population sample of 1323 subjects (45% male) with post-bronchodilation spirometry was studied. 80 subjects (6.0%) and 55 subjects (4.2%) were identified with airflow limitation with GOLD and GLI2012 criteria, respectively. The proportion of overestimation with GOLD increased with age from 25% of cases in 50-year-olds to 54% in 70-year-olds. Using z-score-based grading resulted in more dispersion in severity grading. In conclusion, the GOLD criteria cause a marked overestimation already from 50-year-olds and should be replaced with the GLI2012 criteria to improve diagnostic accuracy.

Clinical phenotypes of obstructive airway diseases in an outpatient population

BACKGROUND AND OBJECTIVES

Historically, obstructive airway diseases such as asthma and COPD are classified as different diseases. Although the definitions are clearly described, classification of patients into these traditional, clinical disease entity can be difficult. Recent evidence that there are complex, overlapping phenotypes of obstructive lung disease. Our aim was to capture clinical phenotypes of obstructive diseases through the use of cluster analysis in a representative patient population at a common Dutch pulmonary outpatient clinic. Clinical physiological and cellular/ molecular markers were used in the analysis.

METHODS

To carry out the cluster analysis, an imputed dataset was created from a random sample of 191 adult patients chosen from a pulmonary outpatient clinic. The selection criteria from the sample included patients with a doctor's diagnosis for asthma or COPD. Detailed assessment of patient pulmonary function, blood eosinophil counts, allergic sensitisation and smoking history was collected.

RESULTS

We observed four distinct clusters with different clinical characteristics of obstructive lung diseases. Cluster 1: patients with a history of extensive cigarette smoking, airway obstruction without signs of emphysema; cluster 2: patients with features of the emphysematous type of COPD; cluster 3: patients with characteristics of allergic asthma; cluster 4: patients with features suggesting an overlap syndrome of atopic asthma and COPD.

CONCLUSION

Four phenotypes of obstructive lung disease were identified amongst patients clinically labelled as asthma or COPD. These findings emphasize the concept that there are different phenotypes of obstructive lung diseases, including overlapping and complementary disease entities. These phenotypes of chronic airways disease can serve to tailor disease management.

The Prevalence of Chronic Obstructive Pulmonary Disease by the Global Lung Initiative Equations in North-Western Russia

BACKGROUND

The prevalence of chronic obstructive pulmonary disease (COPD) varies in different countries, while the cut-off for airflow obstruction (AO) is still contested. No COPD prevalence data based on the Global Lung Initiative (GLI) 2012 equations are available in Russia.

OBJECTIVES

This study aims to assess AO prevalence by the GLI lower limit of normal (GLI-LLN) and the fixed cut-off, to identify AO risk factors and to assess the diagnostic value of respiratory symptoms in north-western Russia.

METHODS

In a north-western Russian population-based sample of 2,974 adults aged 35-70 years, data on socio-demographics, smoking, occupational exposures and respiratory symptoms were collected, and spirometry was performed before and after bronchodilator (BD) administration.

RESULTS

The AO prevalence was 6.8% (95% CI 5.8-7.9) based on the fixed and 4.8% (95% CI 3.9-5.7) based on the GLI-LLN cut-off. 22.5% of the participants with post-BD AO had a positive bronchodilator test, and 1% showed a paradoxical BD response. Of the environmental factors studied, only smoking was independently associated with AO (odds ratio 2.47, 95% CI 1.60-3.82). The positive predictive value of respiratory symptoms for AO was 11% based on the fixed and 8% based on the GLI-LLN cut-off.

CONCLUSIONS

In a sample of adults in north-western Russia, the AO prevalence by the GLI-LLN cut-off was lower than that by the fixed cut-off. The predictive value of respiratory symptoms was low.

Lung function, forced expiratory volume in 1 s decline and COPD hospitalisations over 44 years of follow-up

The use of baseline lung function in the prediction of chronic obstructive pulmonary disease (COPD) hospitalisations, all-cause mortality and lung function decline was assessed in the population-based "Men Born in 1914" cohort.Spirometry was assessed at age 55 years in 689 subjects, of whom 392 had spirometry reassessed at age 68  years. The cohort was divided into three groups using fixed ratio (FR) and lower limit of normal (LLN) criterion: forced expiratory volume in 1 s (FEV1)/vital capacity (VC) ≥70%, FEV1/VC <70% but ≥LLN (FR(+)LLN(-)), and FEV1/VC <70% and <LLN (FR(+)LLN(+)).Over 44 years of follow-up, 88 men were hospitalised due to COPD and 686 died. Hazard ratios (95% CI) for incident COPD hospitalisation were 4.15 (2.24-7.69) for FR(+)LLN(-) and 7.88 (4.82-12.87) for FR(+)LLN(+) (reference FEV1/VC ≥70%). Hazard ratios for death were 1.30 (0.98-1.72) for FR(+)LLN(-) and 1.58 (1.25-2.00) for FR(+)LLN(+). The adjusted FEV1 decline between 55 and 68 years of age was higher for FR(+)LLN(-) and FR(+)LLN(+) relative to the reference. Of those with FR(+)LLN(-) at 55 years, 53% had progressed to the FR(+)LLN(+) group at 68 years.Airflow obstruction at age 55 years is a powerful risk factor for future COPD hospitalisations. The FR(+)LLN(-) group should be carefully evaluated in clinical practice in relation to future risks and potential benefit from early intervention. This is reinforced by the increased FEV1 decline in this group.

Prevalence and underdiagnosis of airway obstruction among middle-aged adults in northern France: The ELISABET study 2011-2013

INTRODUCTION

Airway obstruction (AO), mainly due to chronic obstructive pulmonary disease (COPD) in adults, is a major cause of mortality and poor quality of life. However, few data are available for France. This study was designed to calculate the prevalence AO among middle-aged adults in northern France, explore the associated risk factors and evaluate the underdiagnosis.

METHODS

The Enquête Littoral Souffle Air Biologie Environnement (ELISABET) was a cross-sectional study of a representative sample of 3276 adults aged from 40 to 64 in two urban areas in northern France (Lille and Dunkirk). Participants filled out a questionnaire and performed spirometry testing, without a reversibility test.

RESULTS

The age-standardized estimated prevalence [95% confidence interval] of AO was 16.0% [13.9; 17.9] in Lille and 13.7% [11.7; 15.7] in Dunkirk with the Global initiative for chronic Obstructive Lung Disease (GOLD) definition and 10.8% [9.2; 12.5] and 9.5% [7.9; 11.2] respectively with the lower limit of normal calculated with the Global Lung Initiative (GLI) 2012 equations. AO was associated with age, male gender, tobacco consumption and low body mass index. The underdiagnosis rate was greater than 70%. Previously undiagnosed participants with AO displayed more respiratory symptoms compared with participants without AO and less than participants with previously diagnosed AO.

CONCLUSION

The prevalence of AO in northern France ranged from 9.5 to 16.0%, depending on the centre and definition used. The high underdiagnosis rate observed here suggests that greater efforts should be made to identify individuals presenting with the symptoms and/or risk factors associated with AO.