Reliability of FEV1/FEV6 to diagnose airflow obstruction compared with FEV1/FVC: the PLATINO longitudinal study

Association of Small Airway Functional Indices With Respiratory Symptoms and Comorbidity in Asthmatics: A National Cross-Sectional Study

Background

Small airway dysfunction (SAD) and airway inflammation are vital in asthma exacerbations. Type 2 inflammation (T2), mediated by cytokines from T helper 2 cell (Th2) such as interleukin (IL)-4, IL-5, and IL-13, is a potential mechanism underlying SAD. Research on small airway function in asthma is limited. We aimed to explore the correlation between small airway function and respiratory symptoms and comorbidity in T2 and non-T2 asthma.

Methods

Derived from the National Health and Nutrition Examination Survey (NHANES), our study encompassed 2,420 asthma patients aged 6 - 79 years, including pulmonary function (PF) data such as forced expiratory flow between 25% and 75% of forced vital capacity (FEF25-75), forced expiratory volume in 1 second (FEV1), forced expiratory volume in 3 seconds (FEV3), forced expiratory volume in 6 seconds (FEV6), and forced vital capacity (FVC). To evaluate the small airway function, we calculated z-scores for FEF25-75, FEF25-75/FVC, FEV1/FEV6, and FEV3/FEV6. Logistic regression determined the adjusted odds ratios (aORs) for symptoms and comorbidity.

Results

FEF25-75, FEV1/FEV6, and FEV3/FEV6 correlated with asthmatic symptoms. FEF25-75 had the strongest association with wheezing or whistling attacks. An increase of 1 standard deviations (SD) in FEF25-75 reduced recurrent wheezing (aOR: 0.70; 95% confidence intervals (95% CIs): 0.65 - 0.76) and severe attacks (aOR: 0.67; 95% CI: 0.62 - 0.94). These indices were also linked to dry cough and hay fever, particularly FEV3/FEV6 reducing hay fever risk (aOR: 0.70; 95% CI: 0.55 - 0.91) in non-T2 asthma. FEF25-75/FVC related to persistent (aOR: 0.78; 95% CI: 0.72 - 0.84) and severe attacks (aOR: 1.14; 95% CI: 1.08 - 1.22) in non-T2 groups. Lower indices combined with T2 exposure raised severe attack risk.

Conclusions

In this nationwide study, small airway function correlated with symptom onset, especially in T2 asthma. Small airway injury differed between T2 and non-T2 asthma. Prospective research is needed to establish reference values.

Trajectories of Spirometric Patterns, Obstructive and PRISm, in a Population-Based Cohort in Latin America

Background

Preserved ratio impaired spirometry (PRISm) has been associated with adverse outcomes and increased transition to other spirometric categories over time. We aimed to examine its prevalence, trajectories over time, and outcomes in a population-based sample from Latin America.

Methods

Data were obtained from two population-based surveys of adults from three cities in Latin America (PLATINO study), conducted on the same individuals 5-9 years after their baseline examination. We estimated the frequency of PRISm defined by FEV1/FVC≥0.70 with FEV1 <80%, describing their clinical characteristics, longitudinal transition trajectories over time, factors associated with the transition.

Results

At baseline, 2942 participants completed post-bronchodilator spirometry, and 2026 at both evaluations. The prevalence of normal spirometry was 78%, GOLD-stage 1 10.6%, GOLD 2-4 6.5%, and PRISm was: 5.0% (95% CI 4.2-5.8). PRISm was associated with less schooling, more reports of physician-diagnosis of COPD, wheezing, dyspnea, missing days at work, having ≥2 exacerbations in the previous year but without accelerated lung function decline. Mortality risk was significantly higher in PRISm (HR 1.97, 95% CI 1.2-3.3) and COPD GOLD 1-4 categories (HR 1.79, 95% CI 1.3-2.4) compared with normal spirometry. PRISm at baseline most frequently transitioned to another category at follow-up (46.5%); 26.7% to normal spirometry and 19.8% to COPD. The best predictors of transition to COPD were closeness of FEV1/FVC to 0.70, older age, current smoking, and a longer FET in the second assessment.

Conclusion

PRISm, is a heterogeneous and unstable condition prone to adverse outcomes that require adequate follow-up.

Global, regional, and national prevalence of, and risk factors for, chronic obstructive pulmonary disease (COPD) in 2019: a systematic review and modelling analysis

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an increasingly important cause of morbidity, disability, and mortality worldwide. We aimed to estimate global, regional, and national COPD prevalence and risk factors to guide policy and population interventions.

METHODS

For this systematic review and modelling study, we searched MEDLINE, Embase, Global Health, and CINAHL, for population-based studies on COPD prevalence published between Jan 1, 1990, and Dec 31, 2019. We included data reported using the two main case definitions: the Global Initiative for Chronic Obstructive Lung Disease fixed ratio (GOLD; FEV1/FVC<0·7) and the lower limit of normal (LLN; FEV1/FVC

FINDINGS

We identified 162 articles reporting population-based studies conducted across 260 sites in 65 countries. In 2019, the global prevalence of COPD among people aged 30-79 years was 10·3% (95% CI 8·2-12·8) using the GOLD case definition, which translates to 391·9 million people (95% CI 312·6-487·9), and 7·6% (5·8-10·1) using the LLN definition, which translates to 292·0 million people (219·8-385·6). Using the GOLD definition, we estimated that 391·9 million (95% CI 312·6-487·9) people aged 30-79 years had COPD worldwide in 2019, with most (315·5 million [246·7-399·6]; 80·5%) living in LMICs. The overall prevalence of GOLD-COPD among people aged 30-79 years was the highest in the Western Pacific region (11·7% [95% CI 9·3-14·6]) and lowest in the region of the Americas (6·8% [95% CI 5·6-8·2]). Globally, male sex (OR 2·1 [95% CI 1·8-2·3]), smoking (current smoker 3·2 [2·5-4·0]; ever smoker 2·3 [2·0-2·5]), body-mass index of less than 18·5 kg/m2 (2·2 [1·7-2·7]), biomass exposure (1·4 [1·2-1·7]), and occupational exposure to dust or smoke (1·4 [1·3-1·6]) were all substantial risk factors for COPD.

INTERPRETATION

With more than three-quarters of global COPD cases in LMICs, tackling this chronic condition is a major and increasing challenge for health systems in these settings. In the absence of targeted population-wide efforts and health system reforms in these settings, many of which are under-resourced, achieving a substantial reduction in the burden of COPD globally might remain a difficult task.

FUNDING

National Institute for Health Research and Health Data Research UK.

Collapse

Key Words Collapse

MESH Headings

• Chronic Disease
• Female
• Global Health
• Humans
• Male
• Prevalence
• Pulmonary Disease, Chronic Obstructive/epidemiology
• Risk Factors

Collapse

Grants

• MC_PC_19004 Medical Research Council

Collapse

Affiliation(s)

Davies Adeloye Centre for Global Health, Usher Institute, University of Edinburgh, Edinburgh, UK
Peige Song School of Public Health and Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
Yajie Zhu The George Institute for Global Health, University of Oxford, Oxford, UK
Harry Campbell Centre for Global Health, Usher Institute, University of Edinburgh, Edinburgh, UK
Aziz Sheikh Centre for Global Health, Usher Institute, University of Edinburgh, Edinburgh, UK
Igor Rudan Centre for Global Health, Usher Institute, University of Edinburgh, Edinburgh, UK.

Collapse

Validity of the Handheld Expiratory Flowmeter for COPD Screening in the Primary Care Setting of China

Purpose

The use of simple and affordable screening tools for chronic obstructive pulmonary disease (COPD) is limited. We aimed to assess the validity of a handheld expiratory flowmeter (Vitalograph Ltd., COPD-6^®, Ireland) for COPD screening in Chinese primary care settings.

Methods

In our cross-sectional study, subjects were randomly selected in eight primary care settings. Tests with the handheld expiratory flowmeter and the conventional spirometry were sequentially performed on all participants. The correlation between the handheld expiratory flowmeter and the conventional spirometry was determined. Validity was determined by the area under the receiver operator characteristic curve (AUC) of the forced expiratory volume in one second (FEV₁)_/forced expiratory volume in six seconds (FEV₆) that used to detect airway obstruction. The sensitivity, specificity, predictive values, and likelihood ratio were calculated according to different FEV₁/FEV₆ cut-off points.

Results

A total of 229 subjects (15.4%) were diagnosed with airflow limitation by conventional spirometry. FEV₁, FEV₆, and FEV₁/FEV₆ measured by the handheld expiratory flowmeter were correlated with FEV₁, FVC, and FEV₁/FVC measured by the conventional spirometry (r=0.889, 0.835 and 0.647, p<0.001), respectively. AUC of the FEV₁/FEV₆ to determine airflow obstruction was 0.857 (95% CI: 0.826 to 0.888). No significant difference of AUC was observed between the symptomatic group and the asymptomatic group (AUC=0.869 vs 0.843, P=0.425). A similar phenomenon was found in the AUC of smokers and never-smokers (AUC=0.862 vs 0.840; P=0.515). The cut-off point for FEV₁/FEV₆ was 0.77 and the corresponding sensitivity and specificity were 71.2% and 89.8%, respectively.

Conclusion

The handheld expiratory flowmeter might be used as a screening device for COPD in Chinese primary care settings.

Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement

Background: Spirometry is the most common pulmonary function test. It is widely used in the assessment of lung function to provide objective information used in the diagnosis of lung diseases and monitoring lung health. In 2005, the American Thoracic Society and the European Respiratory Society jointly adopted technical standards for conducting spirometry. Improvements in instrumentation and computational capabilities, together with new research studies and enhanced quality assurance approaches, have led to the need to update the 2005 technical standards for spirometry to take full advantage of current technical capabilities.Methods: This spirometry technical standards document was developed by an international joint task force, appointed by the American Thoracic Society and the European Respiratory Society, with expertise in conducting and analyzing pulmonary function tests, laboratory quality assurance, and developing international standards. A comprehensive review of published evidence was performed. A patient survey was developed to capture patients' experiences.Results: Revisions to the 2005 technical standards for spirometry were made, including the addition of factors that were not previously considered. Evidence to support the revisions was cited when applicable. The experience and expertise of task force members were used to develop recommended best practices.Conclusions: Standards and consensus recommendations are presented for manufacturers, clinicians, operators, and researchers with the aims of increasing the accuracy, precision, and quality of spirometric measurements and improving the patient experience. A comprehensive guide to aid in the implementation of these standards was developed as an online supplement.

Lung function and blood gas abnormalities in patients with acromegaly

OBJECTIVE

Respiratory disorders are common complications of acromegaly patients. We conducted a large-scale survey in the patients with acromegaly and demonstrated the characteristics of their lung function and blood gas.

METHODS

A prospective cohort study was conducted with 115 patients with active acromegaly and 56 patients with nonfunctioning pituitary adenomas. All patients underwent clinical, biological, radiological, lung functional and blood gas assessments.

RESULTS

Acromegaly patients had a higher lung volume than those with nonfunctioning adenomas (forced vital capacity value (FVC) and FVC% predicted: p < 0.001). The small airway was less obstructive in acromegaly patients (higher FEV1% predicted, PEF% predicted, MEF75% predicted, MEF50% predicted, MEF25% predicted: p ≤ 0.001 for all analyses, FEV1/FVC: p = 0.151). The average partial pressure of carbon dioxide in acromegaly patients was higher (p < 0.001), but there was no significant difference in the average partial pressure of oxygen or oxygen saturation between the two groups (p > 0.05). In acromegaly patients, the average age of patients with small airway obstruction was higher than that of patients with normal lung function (p < 0.05), but no significant difference in GH or IGF-1 levels between the two groups were found (p > 0.05).

CONCLUSION

The acromegaly patients in this cohort had increased lung volume. However, there was no evidence demonstrating hypoxemia in acromegaly patients. The small airway was less obstructive in acromegaly patents. Small airway obstruction was observed in elderly patients with acromegaly.

Exposure to biomass smoke, cigarettes, and alcohol modifies the association between tumour necrosis factor (-308G/A, -238G/A) polymorphisms and tuberculosis in Mexican carriers

INTRODUCTION

Exposure to biomass smoke, cigarettes, alcohol, and the impairment of immunoregulation are considered to be risk factors for tuberculosis. Tumour necrosis factor (TNF) -308G/A and -238G/A gene polymorphisms have been associated with tuberculosis. However, the results remain inconsistent. The aim of this study was to determine the association between TNF polymorphisms and tuberculosis in the presence of biomass smoke, cigarettes, and alcohol in a Mexican population.

MATERIAL AND METHODS

TNF polymorphisms were determined in 118 tuberculosis patients and 223 controls. We performed a univariate, bivariate, stratified analysis. Odds ratios, confidence intervals, and p-values were calculated.

RESULTS

Occupational biomass smoke exposure was associated with tuberculosis between the patients and controls (OR = 1.70, 95% CI: 1.08-2.70, p = 0.02). We also found an association of the -308A allele carriers between the patients and controls without exposure to occupational (p = 0.04, OR = 0.16, 95% CI: 0.01-0.92) and in-home (p = 0.02, OR = 0.14, 95% CI: 0.01-0.81) biomass smoke, as well as an association with alcohol (p = 0.01, OR = 0.24, 95% CI: 0.05-0.75). The haplotype analysis revealed an association of the -308A/-238G haplotype between patients and nonconsanguineous controls without exposure to occupational (p = 0.02, OR = 0.12, 95% CI: 0.01-0.99) and in-home (p = 0.01, OR = 0.1, 95% CI: 0.01-0.9) biomass smoke, cigarette use (p = 0.04, OR = 0.28, 95% CI: 0.08-0.98), and alcohol (p = 0.02, OR = 0.22, 95% CI: 0.05-0.88) intake.

CONCLUSIONS

The TNF -308A allele and the -308A/-238G haplotype are associated with tuberculosis, as are exposure to biomass smoke, cigarettes, and alcohol. No association for the -238G/A polymorphism was found. Our results provide insight into a possible protective role of TNF polymorphisms in tuberculosis in our population.

Respiratory Health Outcomes, Rhinitis, and Eczema in Workers from Grain Storage Facilities in Costa Rica

Objectives

To examine the associations of inhalable grain dust exposure with respiratory health outcomes, rhinitis, and eczema reported by workers from rice, wheat, and maize storage facilities.

Methods

A cross-sectional study of 136 workers (73 operators and 63 administrative staff and other workers) from eight Costa Rican grain storage facilities was conducted in 2014-2015. Full-shift personal inhalable dust samples from all workers were collected. Study participants were administered a short version of the European Community Respiratory Health Survey questionnaire to identify symptoms of asthma, chronic bronchitis, rhinitis, and eczema. Associations between grain dust exposure and health outcomes were assessed using multivariable logistic and negative binomial regression models adjusted for age, smoking history, grain type, and presence of pets or farm animals in the home.

Results

The median inhalable grain dust concentration was 2.0 (25th to 75th percentile: 0.3-7.0) mg m-3. Higher concentrations of inhalable dust were associated with increased odds of (i) asthma symptoms or medication use [adjusted Odds ratio (ORa) per 10-fold increase in dust concentration 2.7; 95% confidence interval (CI): 1.3-6.7]; (ii) a score of at least two out of five symptoms suggestive of asthma (ORa 1.2; 95% CI: 1.0-1.3); and (iii) eczema (ORa 3.6; 95% CI: 1.7-9.6). No associations of inhalable grain dust exposure with chronic bronchitis and rhinitis were observed.

Conclusions

High exposure to inhalable dust in Costa Rican grain storage facilities was associated to asthma symptoms and eczema in workers.

Utility of FEV1/FEV6 index in patients with multimorbidity hospitalized for decompensation of chronic diseases

Spirometry remains essential for the diagnosis of airway obstruction. Nevertheless, its performance in elderly hospitalized patients with multimorbidity can be difficult. The aim of this study is to assess the utility of the COPD-6 portable device in this population. We included all patients hospitalized for exacerbation of chronic diseases in a medical ward specialized in the care of multimorbidity patients, between September 2017 and May 2018. A questionnaire including sociodemographic, cognitive and functional impairment, among other variables, was completed the last day of admission. Subsequently, patients attempted to perform three valid respiratory manoeuvres with the COPD-6 device and then conventional spirometry. A total of 184 patients were included (mean age of 79.61 years, 55% men). Forty-seven (25.54%) patients were able to perform complete spirometric manoeuvres and 99 (53.8%) could perform a valid FEV1/FEV6 determination. The inability to perform a valid spirometry was related with the patient’s age, functional physical disability, cognitive impairment or the presence of delirium or dysphagia during admission. Only 9% of patients with a Mini Mental Cognitive Examination (MMEC) lower than 24 points could perform a valid spirometry. Of the patients with an MMEC < 24 points and unable to perform spirometry, 34% were able to complete the FEV1/FEV6 manoeuvres. No differences were found in the Charlson index, multimorbidity scale, number of domiciliary drugs, or length of stay between those patients able and those not able to perform respiratory manoeuvres. The agreement between the values for FEV1 measured with COPD-6 and those observed in the spirometry was good (r: 0.71; p<0.0001). Inability to perform a valid spirometry during hospitalization in elderly patients with multimorbidity is frequent and related with functional and cognitive impairment. FEV1/FEV6 determination using the COPD-6 portable device allows an important percentage of the patients with limitations to complete spirometric measurement.

Chronic Obstructive Pulmonary Disease in Latin America

The PLATINO and PREPOCOL population-based studies documented the prevalence of chronic obstructive pulmonary disease (COPD) in several Latin American (Mexico City, Sao Paulo, Montevideo, Santiago and Caracas) and Colombian (Medellin, Bogota, Barranquilla, Bucaramanga and Cali) cities. COPD ranged between 6.2 and 19.6% in individuals ≥40 years of age, with substantial rates of underdiagnosis (up to 89%) but also overdiagnosis, mostly due to the lack of spirometric confirmation. The main risk factor was tobacco smoking, but male gender and age were also associated with COPD. COPD in never smokers represented about one third of the cases and was associated with previous history of tuberculosis or a diagnosis of asthma. COPD associated with biomass smoke exposure was a common clinical phenotype in Latin America, found as a risk factor in PREPOCOL and other observational studies in the region. Smoking has been decreasing in Latin America and efforts have been made to implement cleaner biomass stoves. Unfortunately, treatment of COPD in Latin America remains highly variable with low rates of smoking cessation counselling, low use of inhaled bronchodilators and influenza vaccination. A primary-care approach to COPD, particularly in the form of integrated programs is lacking but would be critical to improving rates of diagnosis and treatment of COPD.

The accuracy of a handheld "disposable pneumotachograph device" in the spirometric diagnosis of airway obstruction in a Chinese population

Background and aim

It is desirable to facilitate the use of an affordable, reliable, and portable spirometer, for earlier diagnosis of COPD in China, particularly in rural areas. The aim of this study was to assess the agreement of a handheld "disposable pneumotachograph" (D-PNEU) spirometer with the gold standard spirometer and to evaluate its diagnostic accuracy of spirometric classification of airflow obstruction.

Subjects and methods

A total of 241 adult Chinese subjects ranging from healthy to those with mixed levels of pulmonary disease performed spirometry in a conventional body plethysmograph, and using a D-PNEU device in randomized order. The three best spirometric tests were recorded for comparative analysis. A Bland-Altman graph was created to assess the agreement between devices. Using FEV₁/FVC <70% as the "gold standard" for obstruction, the accuracy of classifying the severity of airway obstruction for all subjects was assessed. For the specific individuals (n=159) able to exhale for at least 6 seconds, the accuracy of classifying airway obstruction was further assessed. For this purpose, a receiver operating characteristic curve was used to determine an optimal cutoff point of FEV₁/FEV₆ ratio obtained by the D-PNEU device, which matched the global definition of FEV₁/FVC <70% by the traditional spirometer.

Results

The Bland-Altman analysis showed that the between-device agreement for key airflow metrics was within clinically acceptable limits. The D-PNEU device had 87.1% accuracy in the classification of severity of obstruction in all 241 subjects, when using FEV₁/FVC<70% as the "gold standard" for both devices. The D-PNEU device had 93.7% accuracy in the 159 individuals able to exhale for at least 6 seconds, when a cutoff point of FEV₁/FEV₆ was 74%.

Conclusion

A disposable handheld spirometry device is capable of accurately identifying and quantifying airway obstruction in patients deemed to be at risk, however, caution should be exercised and all available brands should be tested.

Prevalence of COPD and respiratory symptoms associated with biomass smoke exposure in a suburban area

Introduction

Biomass smoke exposure (BSE) is a recognized cause of COPD particularly in rural areas. However, little research has been focused on BSE in suburban areas.

Objective

The aim of this study was to determine the prevalence of COPD, respiratory symptoms (RS) and BSE in women living in a suburban area of Mexico City exposed to BSE.

Methods

A cross-sectional epidemiological survey of a female population aged >35 years was performed using a multistage cluster sampling strategy. The participants completed questionnaires on RS and COPD risk factors. The COPD prevalence was based on the postbronchodilator forced expiratory volume in the first second (FEV₁)/forced vital capacity (FVC) ratio. Of the 1,333 women who completed the respiratory questionnaires, spirometry data were obtained from 1,190, and 969 of these were scored as A–C.

Results

The prevalence of BSE was 47%, and the estimated prevalence of COPD was 2.5% for the total population (n=969) and 3.1% for those with BSE only. The spirometry and oximetry values were significantly lower in women with greater exposure levels. The prevalence of RS (cough, phlegm, wheezing and dyspnea) was significantly higher in the women with BSE compared to those without exposure. We concluded that the association of COPD with biomass exposure is not only a rural phenomenon but also may be observed in the suburban areas of the big cities.

Cut-off value of FEV1/FEV6 as a surrogate for FEV1/FVC for detecting airway obstruction in a Korean population

Background

Forced expiratory volume in 1 second (FEV₁)/forced expiratory volume in 6 seconds (FEV₆) has been proposed as an alternative to FEV₁/forced vital capacity (FVC) for detecting airway obstruction. A fixed cut-off value for FEV₁/FEV₆ in a Korean population is lacking. We investigated a fixed cut-off for FEV₁/FEV₆ as a surrogate for FEV₁/FVC for detecting airway obstruction.

Materials and methods

We used data obtained in the 5 years of the Fifth and Sixth Korean National Health and Nutrition Examination Survey. A total of 14,978 participants aged ≥40 years who underwent spirometry adequately were the study cohort. “Airway obstruction” was a fixed cut-off FEV₁/FVC <70% according to the Global Initiative for Chronic Obstructive Lung Disease guidelines. We also used European Respiratory Society/Global Lung Initiative 2012 equations for the FEV₁/FVC lower limit of normal.

Results

Among the 14,978 participants (43.5% male, 56.5% female; mean age: 56.9 years for men and 57.0 years for women), 14.0% had obstructive lung function according to a fixed cut-off FEV₁/FVC <70%. Optimal FEV₁/FEV₆ cut-off for predicting FEV₁/FVC <70% was 75% using receiver operating characteristic curve analyses (area under receiver operating characteristic curve =0.989, 95% confidence interval 0.987–0.990). This fixed cut-off of FEV₁/FEV₆ showed 93.8% sensitivity, 94.8% specificity, 74.7% positive predictive value, 98.9% negative predictive value, and 0.8 Cohen’s kappa coefficient. When compared with FEV₁/FVC < lower limit of normal, FEV₁/FEV₆ <75% tended to over-diagnose airflow limitation (just like a fixed cut-off of FEV₁/FVC <70%). When grouped according to age and FEV₁ (%), FEV₁/FEV₆ <75% diagnosed more airway obstruction in older participants and mild–moderate stages compared with FEV₁/FVC <70%.

Conclusion

A valid fixed cut-off for detecting airway obstruction in a Korean population is FEV₁/FEV₆ of 75%, but should be used with caution in older individuals and those with mild–moderate airway obstruction.

Plasma Inflammatory Cytokine IL-4, IL-8, IL-10, and TNF-α Levels Correlate with Pulmonary Function in Patients with Asthma-Chronic Obstructive Pulmonary Disease (COPD) Overlap Syndrome

Background

The aim of this study was to investigate the plasma inflammatory cytokine levels and their correlations with pulmonary function in patients with asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS).

Material/Methods

Between January 2013 and December 2014, a total of 96 patients with asthma, acute exacerbation of chronic obstructive pulmonary disease (AECOPD), or ACOS were enrolled, and 35 healthy people were included as a control group. Fasting plasma interleukin (IL)-4, IL-8, IL-10, and tumor necrosis factor alpha (TNF-α) levels were detected using enzyme-linked immunosorbent assay (ELISA). Correlations between the plasma inflammatory cytokine levels and forced expiratory volume in 1 second (FEV1), FEV1/predicted value ratio (FEV1%pred), and FEV1/forced vital capacity (FVC) were analyzed.

Results

IL-4 and IL-8 levels showed statistically significant differences among the 3 groups of patients (both P<0.001); IL-4 level was significantly lower, while IL-8 level was significantly higher in the AECOPD group and ACOS group than those in the asthma group (all P<0.05). IL-10 level and TNF-α level were significantly different among the 3 patient groups (both P<0.001). IL-10 level was significantly different between each of the 2 groups (all P<0.001). TNF-α level in the asthma group was higher than in the AECOPD group and ACOS group (both P<0.001). IL-4 and IL-10 were positively and IL-8 and TNF-α were negatively related with FEV1, FEV1%pred, and FEV1/FVC.

Conclusions

Plasma levels of inflammatory cytokines IL-4, IL-8, IL-10, and TNF-α are related with severity of airway diseases and could be potential markers for the evaluation of asthma, COPD, and ACOS.

A Novel Spirometric Measure Identifies Mild COPD Unidentified by Standard Criteria

BACKGROUND

In chronic obstructive pulmonary disease, both smaller and larger airways are affected. FEV₁ mainly reflects large airways obstruction, while the later fraction of forced exhalation reflects reduction in terminal expiratory flow. In this study, the objective was to evaluate the relationship between spirometric ratios, including the ratio of forced expiratory volume in 3 and 6 seconds (FEV₃/FEV₆), and small airways measures and gas trapping at quantitative chest CT scanning, and clinical outcomes in the Genetic Epidemiology of COPD (COPDGene) cohort.

METHODS

Seven thousand eight hundred fifty-three current and ex-smokers were evaluated for airflow obstruction by using recently defined linear iteratively derived equations of Hansen et al to determine lower limit of normal (LLN) equations for prebronchodilator FEV₁/FVC, FEV₁/FEV₆, FEV₃/FEV₆, and FEV₃/FVC. General linear and ordinal regression models were applied to the relationship between prebronchodilator spirometric and radiologic and clinical data.

RESULTS

Of the 10,311 participants included in the COPDGene phase I study, participants with incomplete quantitative CT scanning or relevant spirometric data were excluded, resulting in 7,853 participants in the present study. Of 4,386 participants with FEV₁/FVC greater than or equal to the LLN, 15.4% had abnormal FEV₃/FEV₆. Compared with normal FEV₃/FEV₆ and FEV₁/FVC, abnormal FEV₃/FEV₆ was associated with significantly greater gas trapping; St. George's Respiratory Questionnaire score; modified Medical Research Council dyspnea score; and BMI, airflow obstruction, dyspnea, and exercise index and with shorter 6-min walking distance (all P < .0001) but not with CT scanning evidence of emphysema.

CONCLUSIONS

Current and ex-smokers with prebronchodilator FEV₃/FEV₆ less than the LLN as the sole abnormality identifies a distinct population with evidence of small airways disease in quantitative CT scanning, impaired indexes of physical function and quality of life otherwise deemed normal by using the current spirometric definition.

Screening for Chronic Obstructive Pulmonary Disease: Validity and Reliability of a Portable Device in Non-Specialized Healthcare Settings

Introduction and Objectives

The underdiagnosis of chronic obstructive pulmonary disease (COPD) could be improved through screening using portable devices simpler than conventional spirometers in specific healthcare settings to reach a higher percentage of the at-risk population. This study was designed to assess the validity and reliability of the COPD-6 portable device to screen for COPD in non-specialized healthcare settings.

Methods

Prospective cohort study to validate a diagnostic test. Three cohorts were recruited: primary care (PC), emergency services (ES) and community pharmacies (CPh). Study population: individuals with risk factors for COPD (>40 years, smoking >10 pack-years, with respiratory symptoms). The values measured using the COPD-6 were FEV1, FEV6 and the FEV1/FEV6 ratio. Subsequently, participants underwent conventional spirometry at hospital, using a post-bronchodilator FEV1/FVC value <0.7 as the gold standard criterion for the COPD diagnosis.

Results

437 participants were included, 362 were valid for the analysis. COPD was diagnosed in 114 patients (31.5%). The area under the ROC curve for the COPD-6 for COPD screening was 0.8.The best cut-off point for the FEV1/FEV6 ratio was 0.8 (sensitivity, 92.1%) using spirometry with the bronchodilator test as the gold standard. There were practically no differences in the COPD-6 performancein the different settings and also regarding age, gender and smoking status.

Conclusions

The COPD-6 device is a valid tool for COPD screening in non-specialized healthcare settings. In this context, the best cut-off point for the FEV1/FEV6 ratio is 0.8.

Incidence of chronic obstructive pulmonary disease based on three spirometric diagnostic criteria in Sao Paulo, Brazil: a nine-year follow-up since the PLATINO prevalence study

CONTEXT AND OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is a respiratory disease of high prevalence and socioeconomic impact worldwide. It affects approximately 16% of the population of São Paulo. The incidence of COPD is still unknown in Brazil. The aim of this study was to estimate new cases of COPD in a population-based sample in São Paulo, Brazil, using three different spirometric diagnostic criteria, and to assess the concordance between these criteria.

DESIGN AND SETTING

Prospective cohort study, in the city of São Paulo, Brazil.

METHODS

A questionnaire was applied and anthropometry and pre and post-bronchodilator spirometry were performed on the same subjects as in the initial PLATINO study (2003) in São Paulo. Data from this follow-up study were added to the original database of the initial phase. Incident COPD cases refer to subjects who developed the disease in accordance with each spirometric criterion during the nine-year follow-up period. The Statistical Package for the Social Sciences, version 17.0 (SPSS Inc., Chicago, IL, USA) was used in the analysis and the significance level was set at P < 0.05.

RESULTS

613 subjects participated in the follow-up. New COPD cases ranged in frequency from 1.4% to 4.0%, depending on the diagnostic criterion used. The concordance between the criteria ranged from 35% to 60%.

CONCLUSION

The incidence of COPD after a nine-year follow-up was high, but varied according to the spirometric criterion used. The agreement between the criteria for identifying new cases of the disease ranged from 35% to 60%.

Instability in the COPD diagnosis upon repeat testing vary with the definition of COPD

Background

A low FEV₁/FVC from post-bronchodilator spirometry is required to diagnose COPD. Both the FEV₁ and the FVC can vary over time; therefore, individuals can be given a diagnosis of mild COPD at one visit, but have normal spirometry during the next appointment, even without an intervention.

Methods

We analyzed two population-based surveys of adults with spirometry carried out for the same individuals 5-9 years after their baseline examination. We determined the factors associated with a change in the spirometry interpretation from one exam to the next utilizing different criteria commonly used to diagnose COPD.

Results

The rate of an inconsistent diagnosis of mild COPD was 11.7% using FEV₁/FVC <0.70, 5.9% using FEV₁/FEV₆ <the lower limit of the normal range, LLN and 4.1% using the GOLD stage 2-4 criterion. The most important factor associated with diagnostic inconsistency was the closeness of the ratio to the LLN during the first examination. Inconsistency decreased with a lower FEV₁.

Conclusions

Using FEV₁/FEV₆ <LLN or GOLD stage 2-4 as the criterion for airflow obstruction reduces inconsistencies in the diagnosis of mild COPD. Further improvement could be obtained by defining a borderline zone around the LLN (e.g. plus or minus 0.6 SD), or repeating the test in patients with borderline results.

Analysis of Forced Expiratory Flow Signals Using the New Luus-Jaakola Optimization Procedure

OBJECTIVE

The aim of this study was to estimate forced vital capacity (FVC) by analyzing incomplete forced expiratory flow-time (FEFT) curves using the new Luus-Jaakola (NLJ) optimization procedure.

METHODS

Complete FEFT curves from 90 subjects with and without respiratory disease were used to validate the method, and its application performance was evaluated by FEFT curves containing incomplete curves from nine obstructive patients. First, a lumped parameter model of the FEFT curve, taking FVC as one of the model parameters, is chosen. The 0- 1 s, 0-1.5 s, . . . , 0-6 s curves chosen from the accepted FEFT curves are, respectively, taken as the local system observations. Then, the NLJ optimization procedure was used to get the estimate of FVC (FVCest) by estimating the model parameters. Finally, FVCest was compared with the measured FVC (FVCmea).

RESULTS

The difference between FVCest and FVCmea decreased with the lengths of observed curves increasing. When the lengths of observed curves reached 3 s, the mean difference (±SD) between FVCest and FVCmea was -11 ± 58 mL. Estimated FVC derived from the incomplete curves were close to FVC from accepted maneuvers.

CONCLUSION

The method can be used to estimate FVC by analyzing an incomplete FEFT curve, providing the length of the curve is more than 3 s.

SIGNIFICANCE

This method can help the subjects who cannot complete the forced expiratory maneuver to provide a reliable estimate of FVC and also can be used to analyze the unacceptable spirometry because of early termination of exhalation.

PLATINO, a nine-year follow-up study of COPD in the city of São Paulo, Brazil: the problem of underdiagnosis

OBJECTIVE:

To determine the underdiagnosis rate in new COPD cases at the end of a nine-year follow-up period-in the study designated "Projeto Latino-Americano de Investigação em Obstrução Pulmonar" (PLATINO, Latin-American Pulmonary Obstruction Investigation Project)-and compare that with the underdiagnosis rate during the initial phase of the study, as well as to identify the clinical features exhibited by the subjects who were not diagnosed until the end of the follow-up phase.

METHODS:

The study population comprised the 1,000 residents of the city of São Paulo, Brazil, who took part in the PLATINO study. Of those, 613 participated in the follow-up phase, during which the subjects were assessed with the same instruments and equipment employed in the initial phase of the study. We used the chi-square test or the independent sample t-test to analyze the underdiagnosis rate and to identify the characteristics of the subjects who were not diagnosed until the end of the follow-up phase.

RESULTS:

The underdiagnosis rate for new COPD cases at the end of the nine-year follow-up period was 70.0%. The underdiagnosis rate during the follow-up phase was 17.5% lower than that reported for the initial phase of the study. The subjects who were not diagnosed until the end of the follow-up phase presented with fewer respiratory symptoms, better pulmonary function, and less severe disease than did those previously diagnosed with COPD.

CONCLUSIONS:

The underdiagnosis rate for new COPD cases was lower in the follow-up phase of the study than in the initial phase. The subjects who were not diagnosed until the end of the follow-up phase of the PLATINO study presented with the same clinical profile as did those who were not diagnosed in the initial phase. These findings underscore the need for spirometry in order to confirm the diagnosis of COPD and provide early intervention.

Efficient screening for COPD using three steps: a cross-sectional study in Mexico City

BACKGROUND

Underdiagnosis of chronic obstructive pulmonary disease (COPD) in primary care can be improved by a more efficient screening strategy.

AIMS

To evaluate a three-step method of screening for COPD consisting of an initial short questionnaire followed by measurement of forced expiratory volume in 1s/forced expiratory volume in 6s (FEV1/FEV6) using an inexpensive pocket spirometer in those with high risk, and diagnostic quality spirometry in those with a low FEV1/FEV6.

METHODS

We analysed two related Mexico City cross-sectional samples. The 2003 Mexico City PLATINO survey (n=542) was used to develop a short questionnaire to determine the risk of COPD and a 2010 survey (n=737) additionally used a pocket spirometer. The discriminatory power of the two instruments was assessed with receiver operator characteristic (ROC) curves using three COPD definitions.

RESULTS

The developed COPD scale included two variables from a simple questionnaire and, in ROC analysis, an area under the curve (AUC) between 0.64 and 0.77 was found to detect COPD. The pocket spirometer had an AUC between 0.85 and 0.88 to detect COPD. Using the COPD scale as a first screening step excluded 35-48% of the total population from further testing at the cost of not detecting 8-18% of those with COPD. Using the pocket spirometer and sending those with a FEV1/FEV6<0.80 for diagnostic quality spirometry is very efficient, and substantially improved the positive predictive value at the cost of not detecting one-third of COPD cases.

CONCLUSIONS

A three-step screening strategy for COPD substantially reduces the need for spirometry testing when only a COPD scale is used for screening.