Global Lung Function Initiative 2012 reference equations for spirometry in the Norwegian population

Outcome-based Definition of the Lower Limit of Normal in Spirometry: A Study of 26,000 Young Adult Men

Rationale: The definition of the lower limit of normal (LLN) of spirometric variables is not well established. Objectives: To investigate the relationship between spirometric abnormalities defined with different thresholds of the LLN and clinical outcomes and to explore the possibility of using different LLN thresholds according to the pretest probability of disease. Methods: We studied the associations between prebronchodilator spirometric abnormalities (forced expiratory volume in the first second [FEV1] < LLN, forced vital capacity [FVC] < LLN, airflow obstruction, spirometric restriction) defined with different thresholds of the LLN (10th, 5th, 2.5th, 1st percentile) and multiple outcomes (prevalence of spirometric abnormalities, respiratory symptoms, all-cause and respiratory mortality) in 26,091 30- to 46-year-old men who participated in a general population survey in Norway in 1988-1990 and were followed for 26 years. Analyses were performed with both local and Global Lung Function Initiative (GLI)-2012 reference equations, stratified by pretest risk (presence or absence of respiratory symptoms), and adjusted for age, body mass index, smoking, and education. Results: In the total population, the prevalence of airflow obstruction was 11.6% with GLI-LLN10, 11.0% with Local-LLN5, 6.1% with GLI-LLN5, 7.6% with Local-LLN2.5, and 3.5% with GLI-LLN2.5. The prevalence of spirometric restriction was 5.9% with GLI-LLN10, 5.2% with Local-LLN5, and 2.8% with GLI-LLN5. Increasingly lower thresholds of the LLN were associated with increasingly higher odds of respiratory symptoms and hazard of mortality for all spirometric abnormalities with both reference equations. Spirometric abnormalities defined with Local-LLN2.5 in asymptomatic subjects were associated with lower hazard of all-cause mortality (hazard ratio [HR], 1.50; 95% confidence interval [CI], 1.15-1.95 for FEV1 < LLN) than those defined with Local-LLN5 in the general population (HR, 1.67; 95% CI, 1.50-1.87 for FEV1 < LLN) and symptomatic subjects (HR, 1.67; 95% CI, 1.46-1.91 for FEV1 < LLN). Overall, the prevalence of spirometric abnormalities and associations with outcomes obtained with Local-LLN5 were comparable to those obtained with GLI-LLN10 and those obtained with Local-LLN2.5 to GLI-LLN5. Conclusions: There is a relationship between statistically based thresholds of the LLN of spirometric variables and clinical outcomes. Different thresholds of the LLN may be used in different risk subgroups of subjects, but the choice of the threshold needs to be evaluated together with the choice of reference equations.

The Short-Term Efficacy of a Three-Week Pulmonary Rehabilitation Program among Patients with Obstructive Lung Diseases

Introduction: The recommended duration for pulmonary rehabilitation stands at a minimum of six weeks; however, this stipulation may pose constraints in various countries due to financial limitations imposed by insurance companies and/or national health funds, as is the case in Poland. Consequently, our study endeavors to analyze the short-term outcomes stemming from a condensed three-week PR regimen administered to patients diagnosed with chronic obstructive pulmonary disease (COPD), asthma, and the concomitance of these conditions (COPD-A)-this is an approach that is standard in the rehabilitation protocols endorsed by our national health fund. Methods: Patients diagnosed with COPD, asthma, and COPD-A, referred to the PR program, underwent retrospective analysis to evaluate the short-term efficacy of a three-week PR program. Patients underwent comprehensive assessment by respiratory physicians and rehabilitation consultants, leading to individualized PR programs. Clinical evaluations occurred at program onset and completion. Results: 125 patients participated: 37 COPD, 61 asthma, and 27 COPD-A. Significant improvements were observed in the COPD Assessment Test (CAT), the consensus-based GINA symptom control tool (GINA-SCT), the Modified Medical Research Council (mMRC) scale, forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), and the 6-min walk test (6 MWT) distance, as well as in the St. George's Respiratory Questionnaire (SGRQ) scores. All groups experienced reduced dyspnea severity and improved exercise tolerance. FEV1 and FVC improved in asthma and COPD-A, but not significantly in COPD. Multivariable logistic regression identified predictive factors for PR response. Conclusions: The study supports the short-term efficacy of the three-week PR program in improving clinical outcomes, exercise tolerance, and quality of life in COPD and asthma patients. Tailoring interventions based on predictors of PR response can optimize outcomes. Further research, particularly of the COPD-A group, is needed for individualized approaches. Larger sample sizes are necessary to confirm our findings.

A prospective study on direct out-of-pocket expenses of hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease in a Philippine tertiary care center

Chronic obstructive pulmonary disease (COPD) is a frequent cause of morbidity and mortality in the Philippines and majority of the economic burden lies in hospitalizations during an exacerbation. Despite coverage of hospitalization cost with the national health insurance system (Phil-Health) for COPD exacerbations, patients often pay out-of-pocket. This study aimed to determine the demographic characteristics of COPD admissions at a Philippine tertiary care center, Philippine General Hospital, and assess mean cost of hospitalization, and identify predictors of prolonged hospitalization and cost > 20,000 Philippine pesos (Php). A prospective cross-sectional study was conducted for 6 months by chart review. Patients were categorized as charity service patients, that is, with no charged professional fees and free medications and private service patients who pay for their health care services. A total of 43 COPD admissions were included. The average daily cost of hospitalization (at peso-dollar rate of 56) for service patients was at $ 75.89 compared to private service patients at $ 285.71. Demographic characteristics and type of accommodation were not significant predictors of prolonged hospital stay nor hospitalization cost of ≥ $ 357. Accommodation cost and professional fees accounted for majority or 61.6% of the overall cost for private patients, while medications and diagnostic tests were the major or 76.01% contributor to the overall cost for charity patients. Despite existence of Phil-health, in-patient coverage for COPD remain insufficient. Measures for maximizing COPD control in the out-patient setting could potentially reduce total cost for this disease.

Updated reference values for static lung volumes from a healthy population in Austria

BACKGROUND

Reference values for lung volumes are necessary to identify and diagnose restrictive lung diseases and hyperinflation, but the values have to be validated in the relevant population. Our aim was to investigate the Global Lung Function Initiative (GLI) reference equations in a representative healthy Austrian population and create population-derived reference equations if poor fit was observed.

METHODS

We analysed spirometry and body plethysmography data from 5371 respiratory healthy subjects (6-80 years) from the Austrian LEAD Study. Fit with the GLI equations was examined using z-scores and distributions within the limits of normality. LEAD reference equations were then created using the LMS method and the generalized additive model of location shape and scale package according to GLI models.

RESULTS

Good fit, defined as mean z-scores between + 0.5 and -0.5,was not observed for the GLI static lung volume equations, with mean z-scores > 0.5 for residual volume (RV), RV/TLC (total lung capacity) and TLC in both sexes, and for expiratory reserve volume (ERV) and inspiratory capacity in females. Distribution within the limits of normality were shifted to the upper limit except for ERV. Population-derived reference equations from the LEAD cohort showed superior fit for lung volumes and provided reproducible results.

CONCLUSION

GLI lung volume reference equations demonstrated a poor fit for our cohort, especially in females. Therefore a new set of Austrian reference equations for static lung volumes was developed, that can be applied to both children and adults (6-80 years of age).

Association of early and current life factors with telomere length in preterm-born children

BACKGROUND

Telomeres shorten after each cell division. Since preterm-born babies are delivered early and often suffer from inflammatory conditions such as bronchopulmonary dysplasia (BPD), their telomere length may be altered.

OBJECTIVES

We assessed associations of early and current life factors with telomere length in saliva samples obtained from 7-12-year-old children born at ≤34 weeks' gestation and term-born controls.

STUDY DESIGN

Relative telomere length was measured by qPCR on extracted DNA. Groups were compared using independent t-tests or ANOVA with post-hoc correction. Linear regression analysis was also used.

RESULTS

534 children had satisfactory telomere data including 383 who were preterm-born (mean (SD) birthweight 1732g (558g), gestation 31.1 (2.6) weeks) and 151 term-born (3464g (510g); 39.8 (1.3) weeks). Telomere length was longer in children who had intrauterine growth restriction (IUGR) at birth: mean (SD): 464.6 (166.3) vs. 418.6 (110.7) in the no-IUGR group; in females: 440.2 (130.1) vs. 405.7 (101.5) in males; and in the least deprived group (397.8 (95.0) vs. 437.6 (121.9) most vs least deprivation quintile). Differences were most notable in females with IUGR. However, telomere length was not different between the preterm and term groups; the BPD and no BPD groups nor was it related to lung function or cardiovascular measurements. In multivariable regression analyses, telomere length was associated with sex, IUGR and deprivation with the greatest difference observed in females with IUGR.

CONCLUSIONS

Telomere length was associated with sex, IUGR and deprivation, especially in females with IUGR, but not with prematurity, BPD, lung function or cardiovascular measurements.

Applicability of the Global Lung Function Initiative prediction equations in Hong Kong Chinese children

BACKGROUND AND OBJECTIVE

This study aimed to assess the applicability of the Global Lung Function Initiative (GLI) prediction equations for spirometry in Hong Kong children and to develop prediction equations based on the Generalized Additive Models for Location, Scale, and Shape (GAMLSS) modeling.

METHODS

Healthy Chinese children and adolescents aged 6-17 years old were recruited from randomly selected schools to undergo spirometry. The measurements were transformed to z-score according to the GLI-2012 equations for South East (SE) Asians and the GLI-2022 global race-neutral equations. Prediction equations for spirometric indices were developed with GAMLSS modeling to identify predictors.

RESULTS

A total of 886 children (477 boys) with a mean age of 12.5 years (standard deviation [SD] 3.3 years) were included. By the GLI-2012 SE Asian equations, positive mean z-scores were observed in forced expiratory volume in 1 s (FEV1 ) (boys: 0.138 ± SD 0.828; girls: 0.206 ± 0.823) and forced vital capacity (FVC) (boys: 0.160 ± 0.930; girls: 0.310 ± 0.895) in both sexes. Negative mean z-scores were observed in FEV1 /FVC ratio (boys: -0.018 ± 0.998; girls: -0.223 ± 0.897). In contrast, negative mean z-scores in FEV1 and FVC, and positive mean z-scores in FEV1 /FVC were observed when adopting the GLI-2022 race-neutral equations. The mean z-scores were all within the range of ±0.5. By GAMLSS models, age and height were significant predictors for all four spirometric indices, while weight was an additional predictor for FVC and FEV1 .

CONCLUSION

Our study provided data supporting the applicability of the GLI prediction equations in Hong Kong Chinese children. The GLI-2012 equations may underestimate FEV1 and FVC, while the GLI-2022 equations may overestimate the parameters, but the differences lie within the physiological limits. By GAMLSS modeling, weight was an additional predictor for FVC and FEV1 .

Bronchiectasis Assessment in Primary Ciliary Dyskinesia: A Non-Invasive Approach Using Forced Oscillation Technique

Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder that results from the dysfunction of motile cilia, which can cause chronic upper and lower respiratory infections leading to bronchiectasis. However, there is a need for additional tools to monitor the progression of bronchiectasis in PCD. The forced oscillation technique (FOT) is an effort-independent lung function test that can be used to evaluate respiratory mechanics. In this retrospective study, we aimed to describe the radiographic findings associated with respiratory impedance (resistance (Rrs) and reactance (Xrs)) measured by FOT in six adult PCD patients and one pediatric with the (RSPH4A (c.921+3_921+6delAAGT (intronic)) founder mutation. We compared the radiographic findings on a high-resolution chest computed tomography (CT) scan with the FOT results. Our findings suggest that respiratory impedance measured by FOT may be a valuable tool for detecting and monitoring the progression of bronchiectasis in PCD patients with the (RSPH4A (c.921+3_921+6delAAGT (intronic)) founder mutation. However, further research is necessary to validate these results and determine the sensitivity and specificity of bronchiectasis monitoring in PCD patients with other genetic mutations.

Comparison of different reference values for lung function: implications of inconsistent use among centers

BACKGROUND

For interpretation of pulmonary function tests (PFTs), reference values based on sex, age, height and ethnicity are needed. In Norway, the European Coal and Steel Community (ECSC) reference values remain widely used, in spite of recommendations to implement the more recent Global Lung Function Initiative (GLI) reference values.

OBJECTIVE

To assess the effects of changing from ECSC to GLI reference values for spirometry, DLCO and static lung volumes, using a clinical cohort of adults with a broad range in age and lung function.

METHODS

PFTs from 577 adults (18-85 years, 45% females) included in recent clinical studies were used to compare ECSC and GLI reference values for FVC, FEV1, DLCO, TLC and RV. Percent predicted and lower limit of normal (LLN) were calculated. Bland-Altman plots were used to assess agreement between GLI and ECSC % predicted values.

RESULTS

In both sexes, GLI % predicted values were lower for FVC and FEV1, and higher for DLCO and RV, compared to ECSC. The disagreement was most pronounced in females, with mean (SD) difference 15 (5) percent points (pp) for DLCO and 17 (9) pp for RV (p < 0.001). With GLI, DLCO was below LLN in 23% of the females, with ECSC in 49% of the females.

CONCLUSIONS

The observed differences between GLI and ECSC reference values are likely to entail significant consequences with respect to criteria for diagnostics and treatment, health care benefits and inclusion in clinical trials. To ensure equity of care, the same reference values should be consistently implemented across centers nationwide.

Pulmonary function in a cohort of heart-healthy individuals from Northern Sweden-a comparison with discordant reference values

BACKGROUND

Dynamic spirometry is an important investigation to differentiate between impaired and normal lung function. This study aimed to evaluate the results of lung function testing in a cohort of subjects from Northern Sweden without any known heart or pulmonary disease. Our focus was to compare with two reference materials that have showed differences in the age-dependency of lung function in Swedish subjects.

METHODS

The study population consisted of 285 healthy adults (148 males, 52%) between 20-90 years of age. The subjects had been randomly selected from the population register for inclusion in a study investigating cardiac function in heart-healthy subjects, but were also assessed with dynamic spirometry. At least seven percent reported smoking. Sixteen subjects presented with pulmonary functional impairments and were excluded from the current study. The sex-specific age-dependency in lung volumes was estimated using the LMS model, where non-linear equations were derived for the mean value (M), the location (L) or skewness, and the scatter (S) or coefficient of variation. This model of the observed lung function data was compared with reference values given by the original LMS model published by the Global Lung Initiative (GLI), and with the model from the recent Obstructive Lung Disease In Norrbotten (OLIN) study, where higher reference values were presented for Swedish subjects than those given by the GLI model.

RESULTS

No differences were found in the age-dependency of pulmonary function between the LMS model developed in the study and the OLIN model. Although the study group included smokers, the original GLI reference values suggested significantly lower normal values of FEV₁ (forced expiratory volume) and FVC (forced vital capacity), and consequently fewer subjects below the lower limit of normality, than both the rederived LMS and OLIN models.

CONCLUSIONS

Our results are in line with previous reports and support that the original GLI reference values underestimate pulmonary function in the adult Swedish population. This underestimation could be reduced by updating the coefficients in the underlying LMS model based on a larger cohort of Swedish citizens than was available in this study.

Normal spirometry prediction equations for the Iranian population

BACKGROUND

This study aimed to establish normative spirometric equations in a healthy population of Iranian children and adults, and compare these equations with those developed by the Caucasian Global Lung Initiative (GLI) for the first time.

METHODS

Spirometric data from healthy Iranian aged 4-82 years sampled in 2019 were used to derive reference equations using the generalized additive model for location (mu), shape (lambda), and scale (sigma).

RESULTS

A total of 418 females and 204 males were included in the study. Applying the GLI standards for the Iranian population resulted from the Z scores of FEV₁, FVC, FEV₁/FVC, and FEF_25-75% was not different from zero. Based on the newly calculated LLN, eleven individuals showed significant values below the LLN for FEV₁/FVC. In all age groups, this frequency was less than 5%, except for men over 70 years of age, which was 12.5%. There are significant differences between new data and GLI for Caucasian data.

CONCLUSION

It is recommended that the values and equations generated from this study should be used by physicians and technicians in their routine practice for the diagnosis and assessment of pulmonary disorders.

Period and cohort effects: consequences on spirometric lung function in Norway during the 20th century

Background and aim

Several factors can influence measured lung function over time. The aim of this study was to investigate period and cohort effects on spirometric measures in a large general population sample in Norway during the 20th century, using Global Lung Function Initiative (GLI-2012) equations as a reference.

Methods

36 466 subjects (born 1894-1969) from four cross-sectional surveys conducted between 1965 and 1999 were included, with harmonised data on smoking habits, respiratory symptoms, lung diseases, education and spirometry. Changes in forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) z-scores in healthy subjects across surveys were explored to investigate period effects. Linear mixed-effects models of FEV₁ and FVC z-scores on birth cohort, with survey as random effect, were used to investigate cohort effects, both in subjects of the total population and in healthy ones.

Results

Relatively higher FEV₁ and FVC z-scores in healthy subjects were found in the first survey (1965-1970) compared to the more recent ones (1988-1999), suggesting period effects. FEV₁ and FVC z-scores increased significantly with birth cohort from 1894 to 1935, after adjustment for covariates. A more stable trend of FEV₁ and FVC z-scores with birth cohort was evidenced for subjects born more recently (1945-1969).

Conclusions

An increase of lung function with year of birth was observed in Norwegian subjects during the first half of the 20th century. The impact of period effects on lung function decreased from 1965 to 1999.

Changes in interpretation of spirometry by implementing the GLI 2012 reference equations: impact on patients tested in a hospital-based PFT lab in a large metropolitan city

BACKGROUND

The Global Lung Function Initiative (GLI-2012) focused on race/ethnicity as an important factor in determining reference values. This study evaluated the effects of changing from Canadian reference equations developed from an all-Caucasian cohort with European ancestry to the GLI-2012 on the interpretation of spirometry in a multiethnic population and aimed to identify the ethnic groups affected by discrepant interpretations.

METHODS

Clinically indicated spirometry in a multiethnic population (aged 20-80 years) collected from 2018 to 2021 was analysed. The predicted and lower limit of normal (LLN) values were calculated using three sets of reference equations: Canadian, GLI-race/ethnic-based (GLI-Race) and GLI-race/ethnic-neutral (GLI-Other). We compared the prevalence of concordance in the abnormal diagnoses (defined as <LLN) for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), and FEV₁/FVC among the three reference values, and evaluated whether race/ethnicity was associated with discordance.

RESULTS

Data from 406 participants were evaluated (non-Caucasian 43.6%). There was 85%-87% concordance for normal/abnormal FVC and FEV₁ interpretations among the Canadian, GLI-Race and GLI-Other reference equations. In all ethnic groups, application of the Canadian references for interpretation led to a higher prevalence of abnormal (<LLN) FVC and FEV₁compared with GLI-Race and GLI-Other. This trend was more prominent in Black, South-East Asian and Mixed/other ethnic groups when comparing the Canadian to the GLI-Race equations. In contrast, the discordance rates were similar among ethnic groups when compared with the GLI-Other reference equations. Interpretation of FEV₁/FVC had a high rate of agreement among all equations.

CONCLUSION

Interpretation using Canadian reference equations was associated with a higher prevalence of restrictive physiology compared with the GLI-2012 equations, particularly if the GLI-Race were used. These observations were mostly found in non-white Caucasian groups, highlighting the need to choose reference equations that reflect closely the ethnic mix of the population being evaluated in order to optimise patient management.

Validation of the Global Lung Function Initiative 2012 Spirometry Reference Values in a Healthy Italian Working Population

BACKGROUND

Several studies showed important differences in the interpretation of spirometry based on different reference values, in particular by comparing European Respiratory Society (ERS) 1993 and Global Lung Function Initiative (GLI) 2012. The validation of new reference values in local populations is essential before they can be used in an appropriate manner. This study aimed to investigate the fit of GLI reference values in a healthy Italian working population.

METHODS

Spirometry data were collected in 1355 workers during their health surveillance medical examination conducted for exposure to chemical and biological risk factors. A single portable spirometer that met the ATS/ERS recommendations for occupational testing was used and calibrated daily.

RESULTS

Average z-score were -0.13 (with a median of -0.17), -0.25 (with a median of -0.24), and 0.18 (with a median of 0.17) for FEV₁, FVC, and FEV₁/FVC ratio, respectively. Considering only the normal-weighted workers, the average z-scores were -0.07 (with a median of -0.16), -0.15 (with a median of -0.16), and 0.07 (with a median of 0.02) for FEV₁, FVC, and FEV₁/FVC ratio, respectively.

CONCLUSIONS

GLI 2012 reference values fit the Italian data satisfactorily, resulting as more accurate than ERS 1993, especially in women, normal-weighted subjects, aged 30-50 years, and for height < 165 cm.

Evaluation of the Global Lung Function Initiative 2012 reference values for spirometry in an Iranian population

Spirometry is an important measurement in detecting and monitoring of chronic obstructive pulmonary disease. The validity of the multi-ethnic Global Lung Function Initiative 2012 (GLI-2012) spirometric norms have been debated in some countries. The aim of the present study was to evaluate the applicability of the GLI reference norms in the Iranian population. A cross-sectional study was performed on 622 healthy non-smoker population (204 males and 418 females, age range: 4 ± 82 years) between July 16 and August 27, 2019 in Iran. Z-scores for spirometric data [FEV₁ (forced expiratory volume in 1 s), FVC (forced vital capacity) FEV₁/FVC, and FEF_25-75% (forced expiratory flow averaged over the middle portion of FVC)] were calculated. According to the agreement approved, a mean Z-score outside the range of ± 0.5 was considered clinically significant. The mean (SD) Z-score values of FEV₁, FVC, FEV₁/FVC and FEF_25-75% were 0.44 (1.21), 0.49 (1.14), 0.11 (1.03), and - 1.13 (0.99) in males and 0.61 (1.14), 0.89 (1.26), 0.17 (0.88) and - 0.49 (0.96) in females, respectively. The Z-score of FEV₁/FVC was below the lower limit of normal (LLN) in 3.43% of men and 2.01% of women (in ≥ 21 years), while these values were significantly higher in people under 21 years old (46.2% in boys and 40.0% in girls). The GLI reference values are not perfect for the Iranian population, especially in children below 10 years old. The use of the GLI reference values was appropriate in population above 21 years; however, they would overestimate the prevalence of airway obstruction in individuals below 21 years.

ERS/ATS technical standard on interpretive strategies for routine lung function tests

BACKGROUND

Appropriate interpretation of pulmonary function tests (PFTs) involves the classification of observed values as within/outside the normal range based on a reference population of healthy individuals, integrating knowledge of physiological determinants of test results into functional classifications and integrating patterns with other clinical data to estimate prognosis. In 2005, the American Thoracic Society (ATS) and European Respiratory Society (ERS) jointly adopted technical standards for the interpretation of PFTs. We aimed to update the 2005 recommendations and incorporate evidence from recent literature to establish new standards for PFT interpretation.

METHODS

This technical standards document was developed by an international joint Task Force, appointed by the ERS/ATS with multidisciplinary expertise in conducting and interpreting PFTs and developing international standards. A comprehensive literature review was conducted and published evidence was reviewed.

RESULTS

Recommendations for the choice of reference equations and limits of normal of the healthy population to identify individuals with unusually low or high results are discussed. Interpretation strategies for bronchodilator responsiveness testing, limits of natural changes over time and severity are also updated. Interpretation of measurements made by spirometry, lung volumes and gas transfer are described as they relate to underlying pathophysiology with updated classification protocols of common impairments.

CONCLUSIONS

Interpretation of PFTs must be complemented with clinical expertise and consideration of the inherent biological variability of the test and the uncertainty of the test result to ensure appropriate interpretation of an individual's lung function measurements.

Regulatory T cells, damage-associated molecular patterns, and myeloid-derived suppressor cells in bronchoalveolar lavage fluid interlinked with chronic obstructive pulmonary disease severity: An observational study

The role of regulatory T cells (Tregs), damage-associated molecular patterns (DAMPs), and myeloid-derived suppressor cells (MDSCs) in the mechanism of innate and adaptive immune responses in chronic obstructive pulmonary disease (COPD) is not well understood.Evaluating the presence of Tregs in the bronchoalveolar lavage fluid (BALF) and peripheral blood in patients with COPD, and assessment of the relationship between Tregs, MDSCs, and DAMPs as factors activating innate and adaptive immune responses. Description of the association between immune and clinical parameters in COPD.Thirty-one patients with COPD were enrolled. Clinical parameters (forced expiratory volume in one second [FEV1], forced vital capacity, total lung capacity [TLC], diffusion capacity of carbon monoxide, and B-BMI, O-obstruction, D-dyspnea, E-exercise [BODE]) were assessed. Tregs and MDSCs were investigated in the BALF and blood using monoclonal antibodies directly conjugated with fluorochromes in flow cytometry. The levels of defensin (DEF2), galectin-1 (Gal-1), galectin-3 (Gal-3), galectin-9 (Gal-9), heat shock protein-27 (HSP27), and surfactant protein A were assessed via sandwich enzyme-linked immunosorbent assay.The percentage of Tregs was significantly higher in the blood than in the BALF, in contrast to the mean fluorescence intensity of forkhead box P3 (FoxP3). Significant associations were observed between Tregs and HSP27 (r = 0.39), Gal-1 (r = 0.55), Gal-9 (r = -0.46), and MDSCs (r = -0.50), and between FoxP3 and Gal-1 (r = -0.42), Gal-3 (r = -0.39), and MDSCs (r = -0.43). Tregs and clinical parameters, including FEV1%pred (r = 0.39), residual volume (RV)%pred (r = -0.56), TLC%pred (r = -0.55), RV/TLC (r = -0.50), arterial oxygen saturation (r = -0.38), and arterial oxygen pressure (r = -0.39) were significantly correlated. FoxP3 was significantly interlinked with RV/TLC (r = -0.52), arterial oxygen pressure (r = 0.42), and BODE index (r = -0.57).The interaction between innate and adaptive immune responses in patients with COPD was confirmed. The expression of Tregs in BALF may have prognostic value in patients with COPD. The conversion of immune responses to clinical parameters appears to be associated with disease severity.

Evaluation of the Global Lung Function Initiative reference equations in Belgian adults

Background

Over the past decade, the Global Lung Function Initiative (GLI) Network has published all-age reference equations on spirometry, diffusing capacity of the lung for carbon monoxide (D_LCO) and lung volumes.

Methods

We evaluated the appropriateness of these equations in an adult Caucasian population. Retrospective lung function data on subjects who performed tests prior to a diagnostic sleep investigation were analysed. From the medical records, lung healthy, lifetime nonsmoking, nonobese subjects were selected, resulting in a population of 1311 subjects (68% male; age range 18–88 years).

Results

Multiple linear regression analysis revealed that lung function z-scores did not differ between subjects with and without sleep apnoea but did depend on height and age. The average forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) z-score was 0 but exhibited an inverse association with height in both sexes (p<0.01). Values of FEV₁ and FVC in both sexes were larger than predicted (mean±sd z-score +0.30±0.96 or 104±13% pred; p<0.01). Overall, static lung volumes and D_LCO were adequately predicted. However, D_LCO z-scores were inversely associated with height in males and age in females (p<0.01). For all lung function indices, the observed scatter was reduced compared with the prediction. Therefore, for all indices <5% of the data were below the GLI-proposed lower limit of normal (LLN) threshold.

Conclusion

GLI reference equations provide an adequate fit in Belgian adults. However, the GLI-proposed LLN is too low for our Antwerp population, resulting in underdiagnosis of disease. Furthermore, airway obstruction and diffusion disorders might be misclassified due to height and age associations.

Overall, GLI reference equations for lung function appropriately describe the data in Belgian adults. However, airway obstruction and diffusion disorders might be misdiagnosed at age and height extremes, and the GLI LLN was too low in this population.https://bit.ly/3jdauLE

Age and body mass index affect fit of spirometry GLI references in schoolchildren

Background

References from the Global Lung Function Initiative (GLI) are widely used to interpret children's spirometry results. We assessed fit for healthy schoolchildren.

Methods

LuftiBus in the School was a population-based cross-sectional study undertaken in 2013–2016 in the canton of Zurich, Switzerland. Parents and their children aged 6–17 years answered questionnaires about respiratory symptoms and lifestyle. Children underwent spirometry in a mobile lung function lab. We calculated GLI-based z-scores for forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), FEV₁/FVC and forced expiratory flow for 25–75% of FVC (FEF_25–75) for healthy White participants. We defined appropriate fit to GLI references by mean values between +0.5 and −0.5 z-scores. We assessed whether fit varied by age, body mass index, height and sex using linear regression models.

Results

We analysed data from 2036 children with valid FEV₁ measurements, of whom 1762 also had valid FVC measurements. The median age was 12.2 years. Fit was appropriate for children aged 6–11 years for all indices. In adolescents aged 12–17 years, fit was appropriate for FEV₁/FVC z-scores (mean±sd −0.09±1.02), but not for FEV₁ (−0.62±0.98), FVC (−0.60±0.98) and FEF_25–75 (−0.54±1.02). Mean FEV₁, FVC and FEF_25–75 z-scores fitted better in children considered overweight (−0.25, −0.13 and −0.38, respectively) than normal weight (−0.55, −0.50 and −0.55, respectively; p-trend <0.001, 0.014 and <0.001, respectively). FEV₁, FVC and FEF_25–75 z-scores depended on both age and height (p-interaction 0.033, 0.019 and <0.001, respectively).

Conclusion

GLI-based FEV₁, FVC, and FEF_25–75 z-scores do not fit White Swiss adolescents well. This should be considered when using reference equations for clinical decision-making, research and international comparison.

This study suggests GLI-based FEV₁, FVC and FEF_25–75% z-scores over-detect abnormal lung function in Swiss adolescents, and more so among slimmer adolescents, which has important implications for clinical care, research and international comparisonshttps://bit.ly/3sbGtAS

Longitudinal lung function in childhood cancer survivors after hematopoietic stem cell transplantation

Longitudinal data on pulmonary function after pediatric allogeneic or autologous hematopoietic stem cell transplantation (HSCT) are rare. We examined pulmonary function and associated risk factors in 5-year childhood cancer survivors (CCSs) longitudinally. We included 74 CCSs diagnosed between 1976 and 2010, treated with HSCT, and with at least two pulmonary function tests performed during follow-up. Median follow-up was 9 years (range 6-13). We described pulmonary function as z-scores for lung volumes (forced vital capacity [FVC], residual volume [RV], total lung capacity [TLC]), flows (forced expiratory volume in 1 s [FEV1], maximal mid-expiratory flow [MMEF]), and diffusion capacity for carbon monoxide (DLCO) and assessed associations with potential risk factors using multivariable regression analysis. The median z-scores for FEV1, FVC, and TLC were below the expected throughout the follow-up period. This was not the case for RV, MMEF and DLCO. Female gender, radiotherapy to the chest, and relapse were associated with lower z-scores of FEV1, FVC, MMEF, RV or DLCO. Childhood cancer survivors after HSCT are at risk of pulmonary dysfunction. The complex and multifactorial etiology of pulmonary dysfunction emphasizes the need for longitudinal prospective studies to better characterize the course and causes of pulmonary function impairment in CCSs.

[Pulmonary ventilation function parameters of children aged 5-14 years in Kunming, China: a comparative analysis of measured values versus predicted values based on Zapletal equation]

OBJECTIVE

To study the percentage of the measured values of the main pulmonary ventilation function parameters in their predicted values based on Zapletal equation among healthy children aged 5-14 years in Kunming, China, and to provide a basis for accurate judgment of pulmonary ventilation function in clinical practice.

METHODS

A total of 702 healthy children aged 5-14 years (352 boys and 350 girls) from Kunming were enrolled. The Jaeger spirometer was used to measure the nine indices:forced vital capacity (FVC), forced expiratory volume in one second (FEV1), ratio of forced expiratory volume in one second to forced vital capacity (FEV1/FVC), maximal mid-expiratory flow (MMEF), forced expiratory flow at 25% of forced vital capacity (FEF25), forced expiratory flow at 50% of forced vital capacity (FEF50), forced expiratory flow at 75% of forced vital capacity (FEF75), peak expiratory flow (PEF), and maximal voluntary ventilation (MVV). The values obtained from the Zapletal equation of predicted values provided by the spirometer were used as the predicted values of children, and the percentage of measured values in predicted values was calculated.

RESULTS

In the 702 children, the percentages of the measured values of the main pulmonary ventilation function parameters PEF, FVC, FEV1, FEV1/FVC, and MVV in their predicted values fluctuated from 102% to 114%, 94% to 108%, 98% to 113%, 98% to 107%, and 141% to 183% respectively. As for the main airway velocity parameters, the percentages of the measured values of FEF25, FEF50, FEF75, and MMEF in their predicted values fluctuated from 98% to 116%, 85% to 102%, 71% to 98%, and 83% to 100% respectively. The percentages of the measured values of PEF, FVC, FEV1, FEV1/FVC, MVV, FEF25, FEF50, FEF75, and MMEF in their predicted values had the lower limits of normal of 88.2%, 88.4%, 92.0%, 94.4%, 118.5%, 82.9%, 70.0%, 62.1%, and 70.1% respectively.

CONCLUSIONS

There are differences between pulmonary ventilation function parameter levels and normal values provided by Zapletal equation in healthy children aged 5-14 years in Kunming. As for the pulmonary ventilation function parameters of PEF, FVC, FEV, FEV1/FVC, MVV, FEF25, FEF50, FEF75, and MMEF in these children, the lower limits of normal of measured values in predicted values may be determined as 88.2%, 88.4%, 92.0%, 94.4%, 118.5%, 82.9%, 70.0%, 62.1%, and 70.1% respectively.

Lung function parameters among Australian Aboriginal 'apparently healthy' adults: an Australian Caucasian and Global Lung Function Initiative (GLI-2012) various ethnic norms comparative study

Background: There is sparse literature evidence evaluating the applicability of the GLI-2012 spirometric norms for Australian Aboriginal adults.Methods: Lung function parameters (LFPs) were compared between Australian Aboriginal and Australian Caucasians, and the fit of Australian Aboriginals LFPs with various ethnic GLI equations was tested.Results: Of 1350 and 5634 Pulmonary function tests (PFTs) in Australian Aboriginal and Australian Caucasian adults, 153 and 208 PFTs matched for anthropometrics and normal chest radiology, respectively. Absolute FVC and FEV₁ values were 20% lower in Australian Aboriginals compared to Australian Caucasians. Differences remained significant after accounting for age, sex, height, weight and smoking status in multivariate regression (FVC -0.84 L (-0.98, -0.71), FEV₁ - 0.72 L (-0.84, -0.59), but with nearly preserved FEV₁/FVC. GLI-2012 transformation resulted in z-scores significantly below zero for each of FVC, FEV₁ and FEV₁/FVC with z-scores ranging from -4.52 (-4.87, -4.16) for North East Asian FVC transformation for males, to -0.34 (-0.73, 0.05) for Black FVC transformation for females.Conclusions: Australian Aboriginal adults had 20% lower values for FVC and FEV₁ but nearly preserved absolute FEV₁/FVC in comparison to Australian Caucasians. The GLI-2012 spirometric norms do not appear to fit for Australian Aboriginal adults regardless of which ethnicity options selected, including 'others/mixed'.

Comparison of five major airflow limitation criteria to identify high-risk individuals with COPD: a contemporary population-based cohort

Background

Different airflow limitation criteria are often used to diagnose COPD. We investigated head-to-head whether Global Initiative for Chronic Obstructive Lung Disease (GOLD) (FEV1/FVC <0.70) and four lower limit of normal (LLN) (FEV1/FVC <LLN) criteria to diagnose airflow limitation differ in identifying individuals at risk of COPD exacerbations and mortality.

Methods

108 246 individuals aged 20–100 years randomly selected from the general population were followed from 2003 through 2018 to determine risk of COPD exacerbations, respiratory mortality and all-cause mortality. LLN criteria used equations from Global Lung Initiative (GLI), National Health and Nutrition Examination Survey (NHANES), European Community for Steel and Coal (ECSC) and Copenhagen City Heart Study (CCHS)/Copenhagen General Population Study (CGPS).

Results

Prevalence of airflow limitation was 17% for GOLD, 8.6% for GLI, 10% for NHANES, 8.2% for ECSC and 14% for CCHS/CGPS. During 14.4 years follow-up, we observed 2745 COPD exacerbations, 762 respiratory deaths and 10 338 all-cause deaths. Comparing individuals with versus without airflow limitation, HRs for COPD exacerbations were 17 (95% CI 14 to 20) for GOLD, 21 (18 to 24) for GLI, 20 (17 to 23) for NHANES, 21 (18 to 24) for ECSC and 18 (16 to 21) for CCHS/CGPS. Corresponding HRs for respiratory mortality were 3.7 (3.1 to 4.3), 6.4 (5.6 to 7.5), 5.7 (4.9 to 6.6), 6.2 (5.3 to 7.2) and 4.5 (3.9 to 5.2), and for all-cause mortality 1.5 (1.4 to 1.5), 1.9 (1.8 to 2.0), 1.8 (1.7 to 1.9), 1.9 (1.8 to 2.0) and 1.7 (1.6 to 1.7), respectively. Differences in Harrell’s C were minute for these outcomes; nonetheless, Harrell’s C was slightly higher for LLN criteria compared with GOLD for mortality outcomes.

Conclusions

The prevalence of airflow limitation ranged from 8% to 17% using GOLD and four different LLN criteria; however, identified individuals with the five different criteria had similar risk of COPD exacerbations and mortality.

Assessment of Global Lung Function Initiative (GLI) reference equations for diffusing capacity in relation to respiratory burden in the Swedish CArdioPulmonary bioImage Study (SCAPIS)

The Global Lung Function Initiative (GLI) has recently published international reference values for diffusing capacity of the lung for carbon monoxide (D _LCO). Lower limit of normal (LLN), i.e. the 5th percentile, usually defines impaired D _LCO We examined if the GLI LLN for D _LCO differs from the LLN in a Swedish population of healthy, never-smoking individuals and how any such differences affect identification of subjects with respiratory burden.Spirometry, D _LCO, chest high-resolution computed tomography (HRCT) and questionnaires were obtained from the first 15 040 participants, aged 50-64 years, of the Swedish CArdioPulmonary bioImage Study (SCAPIS). Both GLI reference values and the lambda-mu-sigma (LMS) method were used to define the LLN in asymptomatic never-smokers without respiratory disease (n=4903, of which 2329 were women).Both the median and LLN for D _LCO from SCAPIS were above the median and LLN from the GLI (p<0.05). The prevalence of D _LCO <GLI LLN (and also <SCAPIS LLN) was 3.9%, while the prevalence of D _LCO >GLI LLN but <SCAPIS LLN was 5.7%. Subjects with D _LCO >GLI LLN but <SCAPIS LLN (n=860) had more emphysema (14.3% versus 4.5%, p<0.001), chronic airflow limitation (8.5% versus 3.9%, p<0.001) and chronic bronchitis (8.3% versus 4.4%, p<0.01) than subjects (n=13 600) with normal D _LCO (>GLI LLN and >SCAPIS LLN). No differences were found with regard to physician-diagnosed asthma.The GLI LLN for D _LCO is lower than the estimated LLN in healthy, never-smoking, middle-aged Swedish adults. Individuals with D _LCO above the GLI LLN but below the SCAPIS LLN had, to a larger extent, an increased respiratory burden. This suggests clinical implications for choosing an adequate LLN for studied populations.

The effect of atmospheric pressure on oxygen saturation and dyspnea: the Tromsø study

A drop in atmospheric pressure, as observed at high altitudes, leads to decreased oxygen saturation. The effect of regular changes in barometric pressure at sea level has never been studied in a general population. A cohort of adults aged 40 years were examined with pulse oximetry at two separate visits, and the local barometric pressure was available from the local weather station. The study aimed at determining the effect of atmospheric pressure on oxygen saturation also called SpO₂, as well as on shortness of breath. Based on spirometry, the participants were divided into two groups, with normal and decreased lung function. Decreased lung function was defined as forced expiratory volume in 1 s (FEV₁) below lower limit or normal (LLN) or FEV₁/FVC (FVC, forced vital capacity) below LLN, with GLI 2012 reference values. The statistical analysis included uni/multivariable linear and logistic regression. A total of 7439 participants of the Tromsø 7 cohort study were included. There was a significant association between barometric pressure and SpO₂ < 96%, and we found that a reduction of 166.67 hPa was needed to get a 1% reduction in SpO₂. The change in atmospheric pressure was not significantly associated with shortness of breath, also not in subjects with reduced lung function.

Predictors of progression in systemic sclerosis patients with interstitial lung disease

Systemic sclerosis (SSc) is a systemic autoimmune disease affecting multiple organ systems, including the lungs. Interstitial lung disease (ILD) is the leading cause of death in SSc.

There are no valid biomarkers to predict the occurrence of SSc-ILD, although auto-antibodies against anti-topoisomerase I and several inflammatory markers are candidate biomarkers that need further evaluation. Chest auscultation, presence of shortness of breath and pulmonary function testing are important diagnostic tools, but lack sensitivity to detect early ILD. Baseline screening with high-resolution computed tomography (HRCT) is therefore necessary to confirm an SSc-ILD diagnosis. Once diagnosed with SSc-ILD, patients' clinical courses are variable and difficult to predict, although certain patient characteristics and biomarkers are associated with disease progression. It is important to monitor patients with SSc-ILD for signs of disease progression, although there is no consensus about which diagnostic tools to use or how often monitoring should occur. In this article, we review methods used to define and predict disease progression in SSc-ILD.

There is no valid definition of SSc-ILD disease progression, but we suggest that either a decline in forced vital capacity (FVC) from baseline of ≥10%, or a decline in FVC of 5–9% in association with a decline in diffusing capacity of the lung for carbon monoxide of ≥15% represents progression. An increase in the radiographic extent of ILD on HRCT imaging would also signify progression. A time period of 1–2 years is generally used for this definition, but a decline over a longer time period may also reflect clinically relevant disease progression.

Lung function tests and chest imaging help predict who has SSc-associated ILD and whether it will progress. In the absence of standardised methods for doctors, we recommend a strategy that combines both lung function tests and chest imaging.http://bit.ly/2uK9ZD2

The association between normal lung function and peak oxygen uptake in patients with exercise intolerance and coronary artery disease

In coronary artery disease (CAD), exercise intolerance with reduced oxygen uptake at peak exercise (VO_2peak) is assumed to primarily reflect cardiovascular limitation. However, oxygen transport and utilization depends on an integrated organ response, to which the normal pulmonary system may influence overall capacity. This study aimed to investigate the associations between normal values of lung function measures and VO_2peak in patients with exercise intolerance and CAD. We hypothesized that forced expiratory lung volume in one second (FEV₁), transfer factor of the lung for carbon monoxide (T_LCO) and T_LCO/alveolar volume (T_LCO/VA) above lower limits of normal (LLN) are associated with VO_2peak in these patients. We assessed patients with established CAD (n = 93; 21 women) referred for evaluation due to exercise intolerance from primary care to a private specialist clinic in Norway. Lung function tests and cardiopulmonary exercise testing (CPET) were performed. Z-scores of FEV₁, FEV₁/forced vital capacity (FVC), T_LCO and T_LCO/VA were calculated using the Global Lung Function Initiative (GLI) software and LLN was defined as the fifth percentile (z = -1.645). Non-obstructive patients, defined by both FEV₁ and FEV₁/FVC above LLN, were assessed. The associations of FEV_1Z-score, T_LCO_Z-score and T_LCO/VA_Z-score above LLN with VO_2peak were investigated using linear regression models. Mean VO_2peak ± standard deviation (SD) was 23.8 ± 6.4 ml/kg/min in men and 19.7 ± 4.4 ml/kg/min in women. On average, one SD increase in FEV₁, T_LCO and T_LCO/VA were associated with 1.4 (95% CI 0.2, 2.6), 2.6 (95% CI 1.2, 4.0) and 1.3 (95% CI 0.2, 2.5) ml/kg/min higher VO_2peak, respectively. In non-obstructive patients with exercise intolerance and CAD, FEV₁, T_LCO and T_LCO/VA above LLN are positively associated with VO_2peak. This may imply a clinically significant influence of normal lung function on exercise capacity in these patients.

Spirometric reference values in the occupational medicine practice

INTRODUCTION

Spirometry is the main pulmonary function test routinely employed in the occupational medicine practice. Its interpretation depends on the choice of the theoretical reference values. Therefore, our objective was to retrospectively evaluate the differences in the spirometric interpretation according to the reference values used.

METHODS

A total of 2462 spirometries performed during health surveillance programs were analyzed. Forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and FEV₁/FVC ratio were compared according to three different reference values: the European Coal and Steel Community (ECSC) 1971, the European Respiratory Society (ERS) 1993, and the Global Lung Initiative (GLI) 2012.

RESULTS

The GLI 2012 provided significantly higher predicted mean FVC and FEV₁ values compared to the ERS 1993 and significantly lower compared to the ECSC 1971. The GLI 2012 were able to detect all the obstructive deficits and mixed patterns diagnosed with ECSC 1971 and ERS 1993, in addition to others not diagnosed by these two latter reference values. The number of restrictive patterns identified through the GLI 2012 was significantly reduced and increased compared to those diagnosed using the ECSC 1971 and the ERS 1993, respectively.

DISCUSSION

In comparison to the GLI 2012, the ERS 1993 values significantly underestimated obstructive and restrictive alterations. Conversely, the ECSC 1971 significantly underestimated obstructive changes, while overestimated restrictive patterns, compared to GLI. Although the GLI reference values may provide a correct spirometric interpretation, their validation in an Italian worker population is necessary to confirm their possible use in routine occupational health programs.

How applicable are GLI 2012 equations to a sample of Middle Eastern school-age children?

BACKGROUND

The Global Lung Function Initiative attempted to formulate global all-age lung function equations. The suitability of these equations to Middle Eastern children was never evaluated; this study will evaluate these equations in addition to other regional ones.

METHODS

Spirometry was conducted for 582 (311 boys) healthy 6- to 13-year-old Jordanian children. z scores, predicted values, percent predicted values, and frequency of records below lower limit than normal (LLN) were calculated for each child using the studied equations.

RESULTS

Although none of the studied equations produced a perfect representation of the study data, the GLI 2012 equations for Caucasians were the most suitable.

CONCLUSION

GLI 2012 equations for Caucasians are a reasonable fit for Jordanian school-aged children.

Comparison of pre- and post-bronchodilator lung function as predictors of mortality: The HUNT Study

BACKGROUND AND OBJECTIVE

Post-bronchodilator (BD) lung function is recommended for the diagnosis of chronic obstructive pulmonary disease (COPD). However, often only pre-BD lung function is used in clinical practice or epidemiological studies. We aimed to compare the discrimination ability of pre-BD and post-BD lung function to predict all-cause mortality.

METHODS

Participants aged ≥40 years with airflow limitation (n = 2538) and COPD (n = 1262) in the second survey of the Nord-Trøndelag Health Study (HUNT2, 1995-1997) were followed up until 31 December 2015. Survival analysis and time-dependent area under the receiver operating characteristic curves (AUC) were used to compare the discrimination ability of pre-BD and post-BD lung function (percent-predicted forced expiratory volume in the first second (FEV1 ) (ppFEV1 ), FEV1 z-score, FEV1 quotient (FEV1 Q), modified Global Initiative for Chronic Obstructive Lung Disease (GOLD) categories or GOLD grades).

RESULTS

Among 2538 participants, 1387 died. The AUC for pre-BD and post-BD ppFEV1 to predict mortality were 60.8 and 61.8 (P = 0.005), respectively, at 20 years' follow-up. The corresponding AUC for FEV1 z-score were 58.5 and 60.4 (P < 0.001), for FEV1 Q were 68.7 and 70.1 (P = 0.002) and for modified GOLD categories were 62.3 and 64.5 (P < 0.001). Among participants with COPD, the AUC for pre-BD and post-BD ppFEV1 were 57.0 and 58.8 (P < 0.001), respectively. The corresponding AUC for FEV1 z-score were 53.1 and 55.8 (P < 0.001), for FEV1 Q were 63.6 and 65.1 (P = 0.037) and for GOLD grades were 56.0 and 57.0 (P = 0.268).

CONCLUSION

Mortality was better predicted by post-BD than by pre-BD lung function; however, they differed only by a small margin. The discrimination ability using GOLD grades among COPD participants was similar.

Impacts of Different Spirometry Reference Equations and Diagnostic Criteria on the Frequency of Airway Obstruction in Adult People of North China

Background and Objective

The reference equations and diagnostic criteria play a critical role in the interpretation of pulmonary function tests (PFTs). The aim was to investigate the impacts of different reference equations and diagnostic criteria on the frequency of airway obstruction in adult people of a large teaching hospital of North China.

Methods

The spirometry data of all adult people who underwent PFTs in Qilu hospital from April 2012 to November 2015 were collected. Two spirometry reference equations, namely, Zhongshan-2011 and Global Lung Function Initiative 2012 (GLI-2012) were compared. The frequency of airway obstruction using different spirometry prediction equations and diagnostic criteria including forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <92% of predicted value and FEV1/FVC <lower limits of normal (LLN) were investigated.

Results

A total of 57,888 subjects were recruited with a mean age of 55.5 ± 13.72. There were significant differences in LLN and predicted value between the GLI-2012 and Zhongshan-2011. The average age of those who had an LLN of FEV1/FVC below 0.7 was 66.59 ± 6.05 years using GLI-2012, which was significantly lower than that in Zhongshan-2011 (77.46±2.63, P<0.001). Using FEV1/FVC<LLN as diagnostic criteria, Zhongshan-2011 identifies more obstructive subjects than GLI-2012 in each age group. In 45–59 or 60–80 age group, more participants were defined as obstructive using FEV1/FVC<92%pred than FEV1/FVC<LLN (both P<0.001).

Conclusion

Zhongshan-2011 identifies more airway obstruction than GLI-2012 in adult people of North China. Compared to FEV1/FVC<LLN, FEV1/FVC<92%pred may lead to overdiagnosis of airway obstruction in elderly people.

Is the Disease Burden from COPD in Norway Falling off? A Study of Time Trends in Three Different Data Sources

Background

Less smoking should lead to fewer COPD cases. We aimed at estimating time trends in the prevalence and burden of COPD in Norway from 2001 to 2017.

Methods

We used pre-bronchodilator spirometry and other health data from persons aged 40–84 years in three surveys of the Tromsø Study, 2001–2002, 2007–2008 and 2015–2016. We applied spirometry lower limits of normal (LLN) according to Global Lung Initiative 2012. Age-standardized prevalence was determined. We defined COPD as FEV₁/FVC<LLN in subjects reporting dyspnea or coughing, and moderate to severe COPD when FEV₁ <LLN was found in addition. We identified hospitalizations due to COPD exacerbations in the Norwegian Patient Registry 2010–2017, and retrieved the use of COPD medication from the Norwegian Prescription Database. Change in prevalence was analyzed by logistic regression.

Results

In the Tromsø Study, the age-standardized prevalence of daily smoking dropped from 29.9% to 14.1% among women and from 31.4% to 12.8% among men (P<0.0001). The age-standardized prevalence of COPD dropped from 7.6% to 5.6% among women (P=0.2) and from 7.3% to 5.6% among men (P=0.003) and of moderate to severe COPD from 5.2% to 2.7% among women (P=0.0003) and from 4.6% to 3.2% among men (P=0.0008). Among men, the yearly age-standardized prevalence of hospitalization due to COPD exacerbation decreased from 3.6 to 3.0 per 1000 inhabitants aged 40–84 years (P<0.0001). Correspondingly, dispensing oral corticosteroids or/and antibiotics for COPD exacerbations dropped from 6.6 to 5.8 per 1000 (P<0.0001), while dispensing maintenance treatment increased (P<0.0001).

Conclusion

COPD morbidity decreased between 2001 and 2017, which might partly be due to less smoking. The drop in smoking prevalence gives promise of a further substantial decrease in the coming decades.

GOLD Classifications, COPD Hospitalization, and All-Cause Mortality in Chronic Obstructive Pulmonary Disease: The HUNT Study

Purpose

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) has published three classifications of COPD from 2007 to 2017. No studies have investigated the ability of these classifications to predict COPD-related hospitalizations. We aimed to compare the discrimination ability of the GOLD 2007, 2011, and 2017 classifications to predict COPD hospitalization and all-cause mortality.

Patients and Methods

We followed 1300 participants with COPD aged ≥40 years who participated in the HUNT Study (1995-1997) through to December 31, 2015. Survival analysis and time-dependent area under receiver operating characteristics curves (AUC) were used to compare the discrimination abilities of the GOLD classifications.

Results

Of the 1300 participants, 522 were hospitalized due to COPD and 896 died over 20.4 years of follow-up. In adjusted models, worsening GOLD 2007, GOLD 2011, or GOLD 2017 categories were associated with higher hazards for COPD hospitalization and all-cause mortality, except for the GOLD 2017 classification and all-cause mortality (ptrend=0.114). In crude models, the AUCs (95% CI) for the GOLD 2007, GOLD 2011, and GOLD 2017 for COPD hospitalization were 63.1 (58.7-66.9), 60.9 (56.1-64.4), and 56.1 (54.0-58.1), respectively, at 20-years' follow-up. Corresponding estimates for all-cause mortality were 57.0 (54.8-59.1), 54.1 (52.1-56.0), and 52.6 (51.0-54.3). The differences in AUCs between the GOLD classifications to predict COPD hospitalization and all-cause mortality were constant over the follow-up time.

Conclusion

The GOLD 2007 classification was better than the GOLD 2011 and 2017 classifications at predicting COPD hospitalization and all-cause mortality.

Reference equations for spirometry in healthy Asian children aged 5 to 18 years in Taiwan

Background and objective

This study aimed to establish reference equations for spirometry in healthy Taiwanese children and assess the applicability of the Global Lung Function Initiative (GLI)-2012 equations to Taiwanese children.

Methods

Spirometric data collected from 757 healthy Taiwanese children aged 5 to 18 years in a population-based cohort study. Prediction equations derived using linear regression and the generalized additive models for location, scale and shape (GAMLSS) method, respectively.

Results

The GLI-2012 South East Asian equations did not provide a close fit with mean ± standard error z-scores of −0.679 ± 0.030 (FVC), −0.186 ± 0.044 (FEV₁), −0.875 ± 0.049 (FEV₁/FVC ratio) and −2.189 ± 0.063 (FEF_25-75) for girls; and 0.238 ± 0.059, −0.061 ± 0.053, −0.513 ± 0.059 and −1.896 ± 0.077 for boys. The proposed GAMLSS models took age, height, and weight into account. GAMLSS models for boys and girls captured the characteristics of spirometric data in the study population closely in contrast to the linear regression models and the GLI-2012 equations.

Conclusion

This study provides up-to-date reference values for spirometry using GAMLSS modeling in healthy Taiwanese children aged 5 to 18 years. Our study provides evidence that the GLI-2012 reference equations are not properly matched to spirometric data in a contemporary Taiwanese child population, indicating the urgent need for an update of GLI reference values by inclusion of more data of non-Caucasian decent.

Associations of Asthma and Asthma Control With Atrial Fibrillation Risk: Results From the Nord-Trøndelag Health Study (HUNT)

Importance

Asthma, a chronic inflammatory airway disease, and atrial fibrillation (AF) share several common pathophysiological mechanisms. Research on the association between asthma and atrial fibrillation is lacking, and to our knowledge, no previous studies have assessed the dose-response association between levels of asthma control and AF.

Objective

To assess the association between asthma, levels of asthma control, and AF.

Design, Setting, and Participants

This prospective population cohort analyzed data on adults from a second and third iteration of the survey-based Nord-Trøndelag Health Study (HUNT) in Norway. All included participants were free from AF at baseline. Atrial fibrillation was ascertained by linking HUNT data with hospital records from the 2 hospitals in Nord-Trøndelag County. Data analysis was completed from May 2017 to November 2017.

Exposures

Self-reported asthma was categorized into 3 groups: those who had ever had asthma, those who self-report being diagnosed with asthma, and those who had active asthma. Asthma control was defined according to Global Initiative for Asthma guidelines and was categorized into controlled, partly controlled, and uncontrolled cases.

Main Outcomes and Measures

Atrial fibrillation.

Results

A total of 54 567 adults were included (of whom 28 821 [52.8%] were women). Of these, 5961 participants (10.9%) reported ever having asthma, 3934 participants (7.2%) reported being diagnosed with asthma, and 2485 participants (4.6%) reported having active asthma. During a mean (SD) follow-up of 15.4 (5.8) years, 2071 participants (3.8%) developed AF. Participants with physician-diagnosed asthma had an estimated 38% higher risk of developing AF (adjusted hazard ratio, 1.38 [95% CI, 1.18-1.61]) compared with participants without asthma. There was a dose-response association between levels of asthma control and risk of AF with the highest risk for AF in participants with uncontrolled asthma (adjusted hazard ratio, 1.74 [95% CI, 1.26-2.42]; P for trend < .001).

Conclusions and Relevance

Asthma and lack of asthma control were associated with moderately increased risks of AF in a dose-response manner. Further studies are needed to explore the underlying mechanisms and clarify causal pathways between asthma and AF.

Global Lung Initiative spirometry references in healthy 3-15-year-old French children

The Global Lung Initiative (GLI) Task Force published references for spirometry derived from data collated from a large population of healthy individuals aged 3–95 years, from 26 countries [1]. However data from French children were not included in these equations and external validation of the references is recommended [2]. Our study's aim was to compare z-score values and distributions obtained using the references of Zapletalet al. [3, 4] (Zap-Ref) for preschool [3] and school children [4] currently used in France with those obtained using the GLI's references (GLI-Ref) as applied to data from 3–15 year-old healthy French children from northern France.

Global Lung Initiative spirometry references satisfactorily fit data of healthy 3- to 15-year-old French childrenhttp://bit.ly/2Z2922R

Global Lung Function Initiative-2012 'other/mixed' spirometry reference equation provides the best overall fit for Australian Aboriginal and/or Torres Strait Islander children and young adults

BACKGROUND AND OBJECTIVE

Ethnic-specific reference equations are recommended when performing spirometry. In the absence of appropriate reference equations for Australian Aboriginal and/or Torres Strait Islanders (Indigenous), we determined whether any of the existing Global Lung Function Initiative (GLI)-2012 equations were suitable for use in Indigenous children/young adults.

METHODS

We performed spirometry on 1278 participants (3-25 years) who were identified as Aboriginal, Torres Strait Islander or 'both'. Questionnaires and medical records were used to identify 'healthy' participants. GLI2012_DataConversion software was used to apply the 'Caucasian', 'African-American' and 'other/mixed' equations.

RESULTS

We included 930 healthy participants. Mean z-scores for forced expiratory volume in 1 s (FEV₁ ) and forced vital capacity (FVC) were lower than the Caucasian predicted values (range: -0.53 to -0.60) and higher than African-American (range: 0.70 to 0.78) but similar to other/mixed (range: 0.00 to 0.08). The distribution of healthy participants around the upper and lower limits of normal (~5%) fit well for the other/mixed equation compared to the Caucasian and African-American equations.

CONCLUSION

Of the available GLI-2012 reference equations, the other/mixed reference equation provides the best overall fit for Indigenous Australian children and young adults (3-25 years). Healthy data from additional communities and adults around Australia will be required to confirm generalizability of findings.

Effect of the Application of the Global Lung Initiative 2012 Spirometry Reference Equation on the Diagnosing and Classifying Degree of Airway Obstruction in Thai Adults Aged 40 to 80 Years Old

Background and objective: Changing to a different spirometry reference equation can result in misinterpretation of spirometric findings. Currently, there is limited data about any discordance between the interpretations of airway obstruction (AO) using the Global Lungs Initiative (GLI) 2012 and the currently employed Thai reference equations (Siriraj) in Thai adults. Therefore, this study aimed to determine differences in diagnosis around AO and classification of the severity of AO using the GLI2012 and Siriraj reference equations in Thai adults. Materials and Methods: We analyzed spirometric results from Thai adults aged 40–80 years old (n = 2084), which were collected at the Lung Health Center, Maharaj Nakorn Chiang Mai Hospital, Chiang Mai, Thailand between January 2005 and December 2015. The diagnoses concerning the AO were interpreted using the GLI2012 and Siriraj reference equations. The severity of AO in each case was classified into five grades, including mild, moderate, moderately severe, severe, or very severe. McNemar’s test was used to analyze differences in diagnosis of AO and classification of the level of severity. The Kappa statistic was used to determine agreements of diagnosis of AO and classification of severity between the two reference equations. Results: There were significant differences in both diagnosis of AO and their classifying severity level between the two reference equations (p-value < 0.001). However, the levels of agreement between the two reference equations were moderate to very good in different age and sex groups (Kappa values ranged from 0.62 to 0.78 for the diagnosis of AO and 0.54 to 0.89 for the classification of severity). Conclusions: Changing from the Siriraj to the GLI2012 reference equations underestimates the proportion of airway obstruction in Thai adults.

Asthma medication in children who are overweight/obese: justified treatment?

BACKGROUND

The prevalence of asthma and obesity have increased over the last decades. A possible association between these two chronic illnesses has been suggested, since the prevalence of asthmatic symptoms rises with increasing Body Mass Index (BMI). However, asthma is only one of several possible causes of shortness of breath in obese children. The aim of this study is to evaluate the prevalence of overtreatment with asthma medication in a cohort overweight/obese children with respiratory symptoms visiting a pediatric outpatient clinic.

METHODS

Children referred to a pediatric outpatient clinic aged ≥4- ≤ 18 years with overweight/obesity (defined as BMI-sds > 1.1) and asthmatic symptoms were included. The diagnosis asthma was evaluated and classified in no, unlikely, probable and confirmed asthma, based on clinical parameters and/or spirometry results. Overtreatment was defined as asthma medication prescribed in participants classified as no or unlikely asthma. And undertreatment as probable or confirmed asthma without asthma medication prescribed .

RESULTS

Three hundred thirty-eight participants were included, of which 92.6% (313/338) had a prescription for asthma medication. Overtreatment was observed in 27.2% (92/338) participants. Nine participants were undertreated.

CONCLUSION

More than 25% overtreatment with asthma medication was observed in a cohort overweight/obese children with asthmatic symptoms. This finding emphasizes that the diagnosis of asthma must be confirmed before commencement of medication. The diagnosis of asthma should be based on standard questionnaires evaluating asthmatic symptoms, lung functions test and regular reassessments. Further studies concerning overtreatment with asthma medication in normal weight pediatric populations are warranted, to evaluate whether overtreatment is specific for overweight/obese children.

The association between dynamic lung volume and peak oxygen uptake in a healthy general population: the HUNT study

Background

Although dynamic lung volume is not considered a limiting factor of peak oxygen uptake (VO_2peak) in healthy subjects, an association between forced expiratory lung volume in one second (FEV₁) and VO_2peak has been reported in a healthy population aged 69 – 77 years. We hypothesized that a corresponding association could be found in a healthy general population including young and middle-aged subjects.

Methods

In a population-based study in Norway, we investigated the association between FEV₁ above the lower limit of normal (LLN) and VO_2peak using linear regression and assessed the ventilatory reserve (VR) in healthy subjects aged 20 – 79 years (n = 741).

Results

On average, one standard deviation (SD) increase in FEV₁ was associated with 1.2 ml/kg/min (95% CI 0.7 – 1.6) higher VO_2peak. The association did not differ statistically by sex (p-value for interaction = 0.16) and was similar (0.9 ml/kg/min, 95% CI 0.2 – 1.5) in a sensitivity analysis including only never-smokers (n = 376). In subjects below and above 45 years of age, corresponding estimates were 1.2 ml/kg/min (95% CI 0.5 – 1.8) and 1.2 ml/kg/min (95% CI 0.5 – 1.9), respectively. Preserved VR (≥ 20%) was observed in 66.6% of men and 86.4% of women.

Conclusions

Normal dynamic lung volume, defined as FEV₁ above LLN, was positively associated with VO_2peak in both men and women, in never-smokers and in subjects below and above 45 years of age. The majority of subjects had preserved VR, and the results suggest that FEV₁ within normal limits may influence VO_2peak in healthy subjects even when no ventilatory limitation to exercise is evident.

The multi-ethnic global lung initiative 2012 (GLI-2012) norms reflect contemporary adult's Algerian spirometry

Background

The validation of the multi-ethnic GLI-2012 spirometric norms has been debated in several countries. However, its applicability in Algeria has not been verified.

Aim

To ascertain how well the GLI-2012 norms fit contemporary adult Algerian spirometric data.

Methods

This was a cross-sectional study of a convenience sample of 300 healthy non-smoker adults (50% men, age range: 18–85 years) recruited from the Algiers region general population. All participants underwent a clinical examination and a plethysmography measurement. Z-scores for some spirometric data [FEV₁, FVC, FEV₁/FVC and forced expiratory flow at 25–75% of FVC (FEF_25-75%)] were calculated. If the average Z-score deviated by “< ± 0.5” from the overall mean, the GLI-2012 norms would be considered as reflective of contemporary Algerian spirometry.

Results

The means±SDs of age, height, weight, FVC, FEV₁, FEV₁/FVC and FEF_25-75% of the participants were, respectively, 48±17 years, 1.65±0.10 m, 73±14 kg, 4.04±1.04 L, 3.18±0.82 L, 0.79±0.05 and 4.09±1.09 L/s. Almost the quarter of participants were obese. The total sample means±SDs Z-scores were 0.22±0.87 for FVC, 0.04±0.88 for FEV₁, -0.34±0.67 for FEV₁/FVC and 0.93±0.79 for FEF_25-75%. For men and women, only the means±SDs of the FEF_25-75% Z-scores exceeded the threshold of “± 0.5”, respectively, 1.13±0.77 and 0.73±0.76.

Conclusion

Results of the present study, performed in an Algerian population of healthy non-smoking adults, supported the applicability of the GLI-2012 norms to interpret FEV₁, FVC and FEV₁/FVC but not the FEF_25-75%.

Global lung function initiative 2012 reference values for spirometry in Asian Americans

Background

Spirometry reference values specifically designed for Asian Americans are currently unavailable. The performance of Global Lung Function Initiative 2012 (GLI-2012) equations on assessing spirometry in Asian Americans has not been evaluated. This study aimed to assess the fitness of relevant GLI-2012 equations for spirometry in Asian Americans.

Methods

Asian subjects who never smoked and had qualified spirometry data were extracted from the National Health and Nutrition Examination Survey (NHANES) 2011–2012. Z-scores of forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), and FEV₁/FVC were separately constructed with GLI-2012 equations for North East (NE) Asians, South East (SE) Asians, and individuals of mixed ethnic origin (Mixed). In addition, Proportions of subjects with observed spirometry data below the lower limit of normal (LLN) were also evaluated on each GLI-2012 equation of interest.

Results

This study included 567 subjects (250 men and 317 women) aged 6–79 years. Spirometry z-scores (z-FEV₁, z-FVC, and z-FEV₁/FVC) based on GLI-2012 Mixed equations had mean values close to zero (− 0.278 to − 0.057) and standard deviations close to one (1.001 to 1.128); additionally, 6.0% (95% confidence interval (CI) 3.1–8.9%) and 6.4% (95% CI 3.7–9.1%) of subjects were with observed data below LLN for FEV₁/FVC in men and women, respectively. In contrast, for NE Asian equations, all mean values of z-FEV₁ and z-FVC were smaller than − 0.5; for SE Asian equations, mean values of z-FEV₁/FVC were significantly smaller than zero in men (− 0.333) and women (− 0.440).

Conclusions

GLI-2012 equations for individuals of mixed ethnic origin adequately fitted spirometry data in this sample of Asian Americans. Future studies with larger sample sizes are needed to confirm these findings.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0658-9) contains supplementary material, which is available to authorized users.

Global Lung Initiative 2012 spirometry reference values in a large Asian cohort of Malay, Chinese and Indian ancestry

BACKGROUND AND OBJECTIVE

Although the multi-ethnic European Respiratory Society/Global Lung Initiative (ERS/GLI) 2012 reference values have been developed, the Taskforce has called for further validation specifically on subpopulations that were under represented such as the Malays, Chinese and Indians, in which the two latter ethnic groups represent about one-third of the world population. Thus, the aims of this study were to evaluate the appropriateness of the ERS/GLI 2012 reference values in a healthy adult Malaysian population and to construct a local lung function reference for the Malaysia population specific to the three major ethnic groups.

METHODS

Acceptable spirometry data were obtained from 30 281 healthy subjects aged 35-70 years comprising Malays, Chinese and Indians from the Malaysian Cohort. Local reference values were calculated using regression analysis and evaluated using ERS/GLI reference values to obtain GLI Z-scores.

RESULTS

The mean (SD) of the forced expiratory volume in 1 s (FEV₁ ) for males were 2.67 (0.46), 2.89 (0.48) and 2.60 (0.46) and females were 1.91 (0.36), 2.13 (0.37) and 1.86 (0.35) for Malays, Chinese and Indians, respectively. For forced vital capacity (FVC), the mean (SD) for males were 3.03 (0.53), 3.28 (0.58) and 2.92 (0.53) and females were 2.15 (0.40), 2.38 (0.43) and 2.07 (0.41) for Malays, Chinese and Indians, respectively. The mean GLI Z-scores were less than -0.5 for FEV₁ and FVC and more than 0.5 for FEV₁ /FVC. A large percentage of subjects in all the three ethnic groups were defined lower than the lower limit of normal.

CONCLUSION

This present and large multi-ethnic Asian-based study demonstrates clinically significant deviation from ERS/GLI 2012 equations for spirometry. It highlights the importance of validating predicted equations for spirometry in local populations.

Prevalence and trend of COPD from 1995-1997 to 2006-2008: The HUNT study, Norway

BACKGROUND

COPD is a major cause of morbidity and mortality across the world and new estimates of prevalence and trend are of great importance. We aimed to estimate the prevalence and trend of COPD from 1995-1997 to 2006-2008 in Norwegian adults ≥40 years from the Nord-Trøndelag Health Study.

MATERIAL AND METHODS

COPD was assessed using a fixed-ratio and lower limit of normal (LLN) criteria. Pre-bronchodilator spirometry was performed during 1995-1997 (n = 7158) and 2006-2008 (n = 8788). The prevalence of COPD was weighted using the inverse probability of selection and predicted probability of response.

RESULTS

The prevalence of pre-bronchodilator COPD was 16.7% in 1995-1997 and 14.8% in 2006-2008 using fixed-ratio criteria, and 10.4% in 1995-1997 and 7.3% in 2006-2008 using LLN criteria. The prevalence of LLN COPD was higher among men (13.0% in 1995-1997, 7.7% in 2006-2008) than women (8.0% in 1995-1997, 6.9% in 2006-2008). From 1995-1997 to 2006-2008, the prevalence decreased among men but remained relatively stable among women. Over the 11-year period, the cumulative incidence of pre-bronchodilator COPD using LLN criteria was 3.3% and 2.7% among men and women respectively. The prevalence of self-reported asthma and respiratory symptoms increased.

CONCLUSIONS

The prevalence declined in men but not in women from 1995-1997 to 2006-2008, and was consistently higher among men than women.