Clinical and radiographic predictors of GOLD-unclassified smokers in the COPDGene study

Air pollution associated with cardiopulmonary disease and mortality among participants with preserved ratio impaired spirometry

BACKGROUND

Epidemiological evidence regarding the association between air pollutants and cardiopulmonary disease, mortality in individuals with preserved ratio impaired spirometry (PRISm), and their combined effects remains unclear.

METHODS

We followed 36,149 participants with PRISm in the UK Biobank study. Annual concentrations of PM2.5, PM10, NO2, NOx, and SO2 at residential addresses were determined using a bilinear interpolation method, accounting for address changes. A multistate model assessed the dynamic associations between air pollutants and cardiopulmonary diseases and mortality in PRISm. Quantile g-computation was used to investigate the joint effects of air pollutants.

RESULTS

Long-term exposure to PM2.5, PM10, NO2, NOx, and SO2 was significantly associated with the risk of cardiopulmonary disease in PRISm. The corresponding hazard ratios (HRs) [95 % confidence intervals (95 % CIs)] per interquartile range (IQR) were 1.49 (1.43, 1.54), 1.52 (1.46, 1.57), 1.34 (1.30, 1.39), 1.30 (1.26, 1.34), and 1.44 (1.41, 1.48), respectively. For mortality, the corresponding HRs (95 % CIs) per IQR were 1.36 (1.25, 1.47), 1.35 (1.24, 1.46), 1.27 (1.18, 1.36), 1.23 (1.15, 1.31), and 1.29 (1.20, 1.39), respectively. In PRISm, quantile g-computation analysis demonstrated that a quartile increase in exposure to a mixture of all air pollutants was positively associated with the risk of cardiopulmonary disease and mortality, with HRs (95 % CIs) of 1.84 (1.76, 3.84) and 1.45 (1.32, 1.57), respectively.

CONCLUSION

Long-term individual and joint exposure to air pollutants (PM2.5, PM10, NO2, NOx, and SO2) might be an important risk factor for cardiopulmonary disease and mortality in high-risk populations with PRISm.

It is high time to discard a cut-off of 0.70 in the diagnosis of COPD

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) has traditionally been diagnosed based on the criterion of an FEV1/FVC <0.70. However, this definition has limitations as it may only detect patients with later-stage disease, when pathologic changes have become irreversible. Consequently, it potentially omits individuals with early-stage disease, in whom the pathologic changes could be delayed or reversed.

AREAS COVERED

This narrative review summarizes recent evidence regarding early-stage COPD, which may not fulfill the spirometric criteria but nonetheless exhibits features of COPD or is at risk of future COPD progression.

EXPERT OPINION

A comprehensive approach, including symptoms assessment, various physiologic tests, and radiologic features, is required to diagnose COPD. This approach is necessary to identify currently underdiagnosed patients and to halt disease progression in at- risk patients.

Risk Factors, Morbidity, and Mortality in Association With Preserved Ratio Impaired Spirometry and Restrictive Spirometric Pattern: Clinical Relevance of Preserved Ratio Impaired Spirometry and Restrictive Spirometric Pattern

BACKGROUND

Preserved ratio impaired spirometry (PRISm) and restrictive spirometric pattern (RSP) are often considered interchangeable in identifying restrictive impairment in spirometry.

RESEARCH QUESTION

Do PRISm and RSP have different individual associations with risk factors, morbidity, and mortality?

STUDY DESIGN AND METHODS

In a cross-sectional and longitudinal study, including 26,091 Norwegian general population men (30 to 46 years of age), we explored the association of PRISm and RSP with smoking habits, BMI, education, respiratory symptoms, self-reported cardiopulmonary disease, and mortality after 26 years of follow-up. PRISm was defined as FEV1/FVC ≥ lower limit of normal (LLN) and FEV1 < LLN, and RSP was defined as FEV1/FVC ≥ LLN and FVC < LLN. We compared the associations of PRISm and RSP to airflow obstruction and normal spirometry, both as mutually (PRISm alone, RSP alone) and nonmutually exclusive (PRISm, RSP) categories, adjusting for age, BMI, smoking, and education. We also conducted sensitivity analyses using Global Initiative for Chronic Obstructive Lung Disease criteria to define spirometric abnormalities.

RESULTS

The prevalence of the mutually exclusive spirometric patterns was as follows: normal 82.4%, obstruction 11.0%, PRISm alone 1.4%, RSP alone 1.7%, and PRISm + RSP 3.5%. PRISm alone patients were frequently obese (11.2%), had active or previous tobacco use, commonly reporting cough, phlegm, wheeze, asthma, and bronchitis. RSP alone patients were both obese (14.6%) and underweight (2.9%), with increased breathlessness, but similar smoking habits to patients with normal spirometry. The prevalence of heart disease was 4.6% in PRISm alone, 2.7% in RSP alone, and 1.6% in obstruction. With normal spirometry as a reference, RSP alone had increased all-cause (hazard ratio [HR], 1.57; 95% CI, 1.21-2.04), cardiovascular (HR, 1.48; 95% CI, 0.88-2.48), diabetes (HR, 6.43; 95% CI, 1.88-21.97), and cancer (excluding lung) mortality (HR, 1.51; 95% CI, 0.95-2.42). PRISm alone had increased respiratory disease mortality (HR, 4.00; 95% CI, 1.22-13.16). Patients with PRISm + RSP had intermediate characteristics and the worst prognosis. Findings were overall confirmed with nonmutually exclusive categories and Global Initiative for Chronic Obstructive Lung Disease criteria.

INTERPRETATION

PRISm and RSP are spirometric patterns with distinct risk factors, morbidity, and mortality, which should be differentiated in future studies.

Quantitative CT Imaging Features Associated with Stable PRISm using Machine Learning

RATIONALE AND OBJECTIVES

The structural lung features that characterize individuals with preserved ratio impaired spirometry (PRISm) that remain stable overtime are unknown. The objective of this study was to use machine learning models with computed tomography (CT) imaging to classify stable PRISm from stable controls and stable COPD and identify discriminative features.

MATERIALS AND METHODS

A total of 596 participants that did not transition between control, PRISm and COPD groups at baseline and 3-year follow-up were evaluated: n = 274 with normal lung function (stable control), n = 22 stable PRISm, and n = 300 stable COPD. Investigated features included: quantitative CT (QCT) features (n = 34), such as total lung volume (%TLCCT) and percentage of ground glass and reticulation (%GG+Reticulationtexture), as well as Radiomic (n = 102) features, including varied intensity zone distribution grainy texture (GLDZMZDV). Logistic regression machine learning models were trained using various feature combinations (Base, Base+QCT, Base+Radiomic, Base+QCT+Radiomic). Model performances were evaluated using area under receiver operator curve (AUC) and comparisons between models were made using DeLong test; feature importance was ranked using Shapley Additive Explanations values.

RESULTS

Machine learning models for all feature combinations achieved AUCs between 0.63-0.84 for stable PRISm vs. stable control, and 0.65-0.92 for stable PRISm vs. stable COPD classification. Models incorporating imaging features outperformed those trained solely on base features (p < 0.05). Compared to stable control and COPD, those with stable PRISm exhibited decreased %TLCCT and increased %GG+Reticulationtexture and GLDZMZDV.

CONCLUSION

These findings suggest that reduced lung volumes, and elevated high-density and ground glass/reticulation patterns on CT imaging are associated with stable PRISm.

Trend of prevalence and characteristics of preserved ratio impaired spirometry (PRISm): Nationwide population-based survey between 2010 and 2019

PURPOSE

This study aimed to evaluate the prevalence, trends, and factors of preserved ratio with impaired spirometry (PRISm) by using a nationally representative sample.

PATIENTS AND METHODS

The datasets of the Korea National Health and Nutrition Examination Survey 2010-2019 were used: of total 32,949 participants aged ≥40 and no missing data on spirometry, 24,523 with normal, 4,623 with obstructive, and 3,803 with PRISm were identified. PRISm was defined as FEV1/FVC ≥70% and FEV1% of the predicted value (%pred) <80. PRISm-lower limit of normal (LLN) was defined when FEV1/FVC ≥LLN and FEV1

RESULTS

Estimated average prevalence of PRISm was 10.4% (PRISm-LLN 11.1%). Joinpoint regression analyses found a relatively stable trend of PRISm for both fixed ratio and LLN. The multivariable-adjusted logistic regression model showed female sex, BMI ≥25 kg/m2, metabolic syndrome, hypertriglyceridemia, abdominal obesity, low HDL-choleterol, hypertension, and diabetes were associated with the increased probability of PRISm.

CONCLUSION

Whenever a PRISm pattern is identified in a clinical context, it may be necessary to measure absolute lung volumes to investigate underlying physiological abnormalities and to identify factors that is modifiable.

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Key Words Collapse

MESH Headings

• Humans
• Spirometry
• Female
• Male
• Middle Aged
• Prevalence
• Republic of Korea/epidemiology
• Adult
• Aged
• Nutrition Surveys
• Forced Expiratory Volume
• Pulmonary Disease, Chronic Obstructive/epidemiology
• Pulmonary Disease, Chronic Obstructive/physiopathology
• Pulmonary Disease, Chronic Obstructive/diagnosis

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Grants

• Ministry of Health and Welfare
• Korean Health Industry Development Institute

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Affiliation(s)

Hyunji Choi Department of Laboratory Medicine, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan, Republic of Korea
Chul-Ho Oak Division of Pulmonology, Department of Internal Medicine, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan, Republic of Korea
Mann-Hong Jung Division of Pulmonology, Department of Internal Medicine, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan, Republic of Korea
Tae-Won Jang Division of Pulmonology, Department of Internal Medicine, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan, Republic of Korea
Sung-Jin Nam Division of Pulmonology, Department of Internal Medicine, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan, Republic of Korea
Taemin Yoon Center for Future Medicine, Kosin University Gospel Hospital, Busan, Republic of Korea

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Risks of Dementia in a General Japanese Older Population With Preserved Ratio Impaired Spirometry: The Hisayama Study

BACKGROUND

Studies on the association between preserved ratio impaired spirometry (PRISm) and dementia are limited. Indeed, PRISm has often been overlooked or ignored as an index of lung function impairment. Therefore, we investigated the association of PRISm with the risk for the development of dementia in an older Japanese population.

METHODS

A total of 1,202 community-dwelling, older Japanese participants aged ≥65 years without dementia were followed up for a median of 5.0 years. Participants were categorized by spirometry as follows: normal spirometry (FEV1/FVC ≥0.70 and FEV1 ≥80% predicted), PRISm (≥0.70 and <80%), airflow limitation (AFL) Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 (<0.70 and ≥80%), and AFL GOLD 2 to 4 (<0.70 and <80%). Hazard ratios (HRs) and their 95% confidence intervals (CIs) were computed using a Cox proportional hazards model.

RESULTS

During the follow-up period, 122 participants developed dementia. The age- and sex-adjusted incidences of dementia in the participants with normal spirometry, PRISm, AFL GOLD 1, and AFL GOLD 2 to 4 were 20.5, 37.0, 18.4, and 28.6 per 1,000 person-years, respectively. Participants with PRISm had a higher risk of dementia (HR 2.04; 95% CI, 1.19-3.49) than those with normal spirometry after adjusting for confounders. Moreover, both reduced FEV1% predicted values and FVC% predicted values were associated with the risk of dementia.

CONCLUSION

PRISm was associated with an increased risk of dementia in a general older Japanese population.

Increased postoperative complications after laparoscopic gastrectomy in patients with preserved ratio impaired spirometry

BACKGROUND

Preserved ratio impaired spirometry (PRISm), defined as decreased forced expiratory volume in the first second in the setting of normal ratio, is associated with an increased risk of respiratory disease and systemic comorbidities. Unlike severe obstructive pulmonary disease, little is known about the impact of PRISm on short-term outcomes in patients undergoing laparoscopic gastrectomy (LG) and its association with small airway dysfunction (SAD).

METHODS

This study enrolled 830 patients who underwent preoperative spirometry and LG between January 2021 and August 2023. Of these, 228 patients were excluded. Participants were categorized into 3 groups based on their baseline lung function, and postoperative outcomes were subsequently analyzed. Potential associations between postoperative outcomes and various clinical variables were examined using univariate and multivariate analyses.

RESULTS

PRISm was identified in 16.6% of the patients, whereas SAD was present in 20.4%. The incidence of postoperative pulmonary complications (PPCs) was notably higher in the SAD group (20.3% vs 9.8%, P = .002) and the PRISm group (28.0% vs 9.8%, P < .001) than the normal group. Among the 3 groups, pneumonia was the most frequently observed PPC. Multivariate analysis revealed that both SAD (odds ratio [OR], 2.34; 95% CI, 1.30-4.22; P = .005) and PRISm (OR, 3.26; 95% CI, 1.80-5.90; P < .001) independently constituted significant risk factors associated with the occurrence of PPCs. Univariate analysis showed that female was a possible risk factor for PPCs in PRISm group.

CONCLUSION

Our study showed that PRISm and SAD were associated with the increased PPCs in patients undergoing LG for gastric cancer.

Race Adjustment of Pulmonary Function Tests in the Diagnosis and Management of COPD: A Scoping Review

Aim

Increasing evidence suggests that the inclusion of self-identified race in clinical decision algorithms may perpetuate longstanding inequities. Until recently, most pulmonary function tests utilized separate reference equations that are race/ethnicity based.

Purpose

We assess the magnitude and scope of the available literature on the negative impact of race-based pulmonary function prediction equations on relevant outcomes in African Americans with COPD.

Methods

We performed a scoping review utilizing an English language search on PubMed/Medline, Embase, Scopus, and Web of Science in September 2022 and updated it in December 2023. We searched for publications regarding the effect of race-specific vs race-neutral, race-free, or race-reversed lung function testing algorithms on the diagnosis of COPD and COPD-related physiologic and functional measures. Joanna Briggs Institute (JBI) guidelines were utilized for this scoping review. Eligibility criteria: The search was restricted to adults with COPD. We excluded publications on other lung disorders, non-English language publications, or studies that did not include African Americans. The search identified publications. Ultimately, six peer-reviewed publications and four conference abstracts were selected for this review.

Results

Removal of race from lung function prediction equations often had opposite effects in African Americans and Whites, specifically regarding the severity of lung function impairment. Symptoms and objective findings were better aligned when race-specific reference values were not used. Race-neutral prediction algorithms uniformly resulted in reclassifying severity in the African Americans studied.

Conclusion

The limited literature does not support the use of race-based lung function prediction equations. However, this assertion does not provide guidance for every specific clinical situation. For African Americans with COPD, the use of race-based prediction equations appears to fall short in enhancing diagnostic accuracy, classifying severity of impairment, or predicting subsequent clinical events. We do not have information comparing race-neutral vs race-based algorithms on prediction of progression of COPD. We conclude that the elimination of race-based reference values potentially reduces underestimation of disease severity in African Americans with COPD.

Chronic obstructive pulmonary disease (COPD) and COPD-like phenotypes

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease. Historically, two COPD phenotypes have been described: chronic bronchitis and emphysema. Although these phenotypes may provide additional characterization of the pathophysiology of the disease, they are not extensive enough to reflect the heterogeneity of COPD and do not provide granular categorization that indicates specific treatment, perhaps with the exception of adding inhaled glucocorticoids (ICS) in patients with chronic bronchitis. In this review, we describe COPD phenotypes that provide prognostication and/or indicate specific treatment. We also describe COPD-like phenotypes that do not necessarily meet the current diagnostic criteria for COPD but provide additional prognostication and may be the targets for future clinical trials.

Preserved Ratio Impaired Spirometry (PRISm): A Global Epidemiological Overview, Radiographic Characteristics, Comorbid Associations, and Differentiation from Chronic Obstructive Pulmonary Disease

Preserved Ratio Impaired Spirometry (PRISm) manifests notable epidemiological disparities across the globe, with its prevalence and influential factors showcasing pronounced diversities among various geographical territories and demographics. The prevalence of PRISm fluctuates considerably among regions such as Latin America, the United States, and Asian nations, potentially correlating with a myriad of determinants, including socioeconomic status, environmental factors, and lifestyle modalities. Concurrently, the link between PRISm and health risks and other disorders, especially its distinction and interrelation with chronic obstructive pulmonary disease (COPD), has become a pivotal subject of scientific enquiry. Radiographic anomalies, such as perturbations in the pulmonary parenchyma and structural alterations, are posited as salient characteristics of PRISm. Furthermore, PRISm unveils intricate associations with multiple comorbidities, inclusive of hypertension and type 2 diabetes, thereby amplifying the intricacy in comprehending and managing this condition. In this review, we aim to holistically elucidate the epidemiological peculiarities of PRISm, its potential aetiological contributors, its nexus with COPD, and its association with radiographic aberrations and other comorbidities. An integrative understanding of these dimensions will provide pivotal insights for the formulation of more precise and personalised preventative and therapeutic strategies.

The rate of hypercapnic respiratory failure in a pulmonary function test laboratory database

Hypercapnia rates are in the range 3.6-12% among those with abnormal spirometry and FEV1 ≥80% pred, and 53-58% among those with FEV1 <35% pred. Both airflow obstruction and preserved ratio impaired spirometry are associated with higher risk of CHRF. https://bit.ly/3H8DlfM.

Acute Exacerbation and Longitudinal Lung Function Change of Preserved Ratio Impaired Spirometry

Background

Preserved ratio impaired spirometry (PRISm) is a heterogeneous disease entity. Limited data are available regarding its prevalence, clinical course, or prognosis. We aimed to evaluate the longitudinal clinical course of patients with PRISm compared with chronic obstructive pulmonary disease (COPD).

Methods

A retrospective study enrolled PRISm and COPD patients who underwent chest computed tomography and longitudinal pulmonary function tests between January 2013 and December 2020. We compared the incidence of acute exacerbations and lung function changes between PRISm and COPD patients.

Results

Of the 623 patients, 40 and 583 had PRISm and COPD, respectively. Compared to COPD patients, PRISm patients were younger, more likely to be female and have a history of tuberculosis, and less likely to be smokers. They also had less severe comorbidities, lower forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (DLCO). The clinical course was not significantly different between the PRISm and COPD patients in terms of the risk of moderate-to-severe acute exacerbations or proportion of frequent exacerbators. During follow-up, PRISm patients had a significantly slower annual decline of forced expiratory volume in 1 second, FVC, and DLCO than COPD patients.

Conclusion

PRISm patients had no significant difference in the risk of acute exacerbations, but a significantly slower decline of lung function during longitudinal follow-up, compared with COPD patients.

The many faces of COPD in real life: a longitudinal analysis of the NOVELTY cohort

Background

The diagnosis of COPD requires the demonstration of non-fully reversible airflow limitation by spirometry in the appropriate clinical context. Yet, there are patients with symptoms and relevant exposures suggestive of COPD with either normal spirometry (pre-COPD) or preserved ratio but impaired spirometry (PRISm). Their prevalence, clinical characteristics and associated outcomes in a real-life setting are unclear.

Methods

To investigate them, we studied 3183 patients diagnosed with COPD by their attending physician included in the NOVELTY study (clinicaltrials.gov identifier NCT02760329), a global, 3-year, observational, real-life cohort that included patients recruited from both primary and specialist care clinics in 18 countries.

Results

We found that 1) approximately a quarter of patients diagnosed with (and treated for) COPD in real life did not fulfil the spirometric diagnostic criteria recommended by the Global Initiative for Chronic Obstructive Lung Disease (GOLD), and could be instead categorised as pre-COPD (13%) or PRISm (14%); 2) disease burden (symptoms and exacerbations) was highest in GOLD 3-4 patients (exacerbations per person-year (PPY) 0.82) and lower but similar in those in GOLD 1-2, pre-COPD and PRISm (exacerbations range 0.27-0.43 PPY); 3) lung function decline was highest in pre-COPD and GOLD 1-2, and much less pronounced in PRISm and GOLD 3-4; 4) PRISm and pre-COPD were not stable diagnostic categories and change substantially over time; and 5) all-cause mortality was highest in GOLD 3-4, lowest in pre-COPD, and intermediate and similar in GOLD 1-2 and PRISm.

Conclusions

Patients diagnosed COPD in a real-life clinical setting present great diversity in symptom burden, progression and survival, warranting medical attention.

Early Evidence of Chronic Obstructive Pulmonary Disease Obscured by Race-Specific Prediction Equations

Rationale: The identification of early chronic obstructive pulmonary disease (COPD) is essential to appropriately counsel patients regarding smoking cessation, provide symptomatic treatment, and eventually develop disease-modifying treatments. Disease severity in COPD is defined using race-specific spirometry equations. These may disadvantage non-White individuals in diagnosis and care. Objectives: Determine the impact of race-specific equations on African American (AA) versus non-Hispanic White individuals. Methods: Cross-sectional analyses of the COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease) cohort were conducted, comparing non-Hispanic White (n = 6,766) and AA (n = 3,366) participants for COPD manifestations. Measurements and Main Results: Spirometric classifications using race-specific, multiethnic, and "race-reversed" prediction equations (NHANES [National Health and Nutrition Examination Survey] and Global Lung Function Initiative "Other" and "Global") were compared, as were respiratory symptoms, 6-minute-walk distance, computed tomography imaging, respiratory exacerbations, and St. George's Respiratory Questionnaire. Application of different prediction equations to the cohort resulted in different classifications by stage, with NHANES and Global Lung Function Initiative race-specific equations being minimally different, but race-reversed equations moving AA participants to more severe stages and especially between the Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 0 and preserved ratio impaired spirometry groups. Classification using the established NHANES race-specific equations demonstrated that for each of GOLD stages 1-4, AA participants were younger, had fewer pack-years and more current smoking, but had more exacerbations, shorter 6-minute-walk distance, greater dyspnea, and worse BODE (body mass index, airway obstruction, dyspnea, and exercise capacity) scores and St. George's Respiratory Questionnaire scores. Differences were greatest in GOLD stages 1 and 2. Race-reversed equations reclassified 774 AA participants (43%) from GOLD stage 0 to preserved ratio impaired spirometry. Conclusions: Race-specific equations underestimated disease severity among AA participants. These effects were particularly evident in early disease and may result in late detection of COPD.

Subtypes of Patients with Mild to Moderate Airflow Limitation as Predictors of Chronic Obstructive Pulmonary Disease Exacerbation

COPD is a heterogeneous disease, and its acute exacerbation is a major prognostic factor. We used cluster analysis to predict COPD exacerbation due to subtypes of mild-moderate airflow limitation. In all, 924 patients from the Korea COPD Subgroup Study cohort, with a forced expiratory volume (FEV1) ≥ 50% and documented age, body mass index (BMI), smoking status, smoking pack-years, COPD assessment test (CAT) score, predicted post-bronchodilator FEV1, were enrolled. Four groups, putative chronic bronchitis (n = 224), emphysema (n = 235), young smokers (n = 248), and near normal (n = 217), were identified. The chronic bronchitis group had the highest BMI, and the one with emphysema had the oldest age, lowest BMI, and highest smoking pack-years. The young smokers group had the youngest age and the highest proportion of current smokers. The near-normal group had the highest proportion of never-smokers and near-normal lung function. When compared with the near-normal group, the emphysema group had a higher risk of acute exacerbation (OR: 1.93, 95% CI: 1.29-2.88). However, multiple logistic regression showed that chronic bronchitis (OR: 2.887, 95% CI: 1.065-8.192), predicted functional residual capacity (OR: 1.023, 95% CI: 1.007-1.040), fibrinogen (OR: 1.004, 95% CI: 1.001-1.008), and gastroesophageal reflux disease were independent predictors of exacerbation (OR: 2.646, 95% CI: 1.142-6.181). The exacerbation-susceptible subtypes require more aggressive prevention strategies.

Heterogeneity and Progression of Chronic Obstructive Pulmonary Disease: Emphysema-Predominant and Non-Emphysema-Predominant Disease

While variation in emphysema severity between patients with chronic obstructive pulmonary disease (COPD) is well-recognized, clinically applicable definitions of the emphysema-predominant disease (EPD) and non-emphysema-predominant disease (NEPD) subtypes have not been established. To study the clinical relevance of the EPD and NEPD subtypes, we tested the association of these subtypes with prospective decline in forced expiratory volume in 1 second (FEV1) and mortality among 3,427 subjects with Global Initiative for Chronic Obstructive Lung Disease (GOLD) spirometric grade 2-4 COPD at baseline in the Genetic Epidemiology of COPD (COPDGene) Study, an ongoing national multicenter study that started in 2007. NEPD was defined as airflow obstruction with less than 5% computed tomography (CT) quantitative densitometric emphysema at -950 Hounsfield units, and EPD was defined as airflow obstruction with 10% or greater CT emphysema. Mixed-effects models for FEV1 demonstrated larger average annual FEV1 loss in EPD subjects than in NEPD subjects (-10.2 mL/year; P < 0.001), and subtype-specific associations with FEV1 decline were identified. Cox proportional hazards models showed higher risk of mortality among EPD patients versus NEPD patients (hazard ratio = 1.46, 95% confidence interval: 1.34, 1.60; P < 0.001). To determine whether the NEPD/EPD dichotomy is captured by previously described COPDGene subtypes, we used logistic regression and receiver operating characteristic (ROC) curve analysis to predict NEPD/EPD membership using these previous subtype definitions. The analysis generally showed excellent discrimination, with areas under the ROC curve greater than 0.9. The NEPD and EPD COPD subtypes capture important aspects of COPD heterogeneity and are associated with different rates of disease progression and mortality.

Differential impacts between fat mass index and fat-free mass index on patients with COPD

BACKGROUND

Differences in the clinical impacts of fat mass index (FMI) and fat-free mass index (FFMI) remain unclear in patients with chronic obstructive pulmonary disease (COPD). We hypothesized that FMI and FFMI have different impacts on 1) emphysema and 2) pulmonary function and health-related quality of life of COPD patients.

METHODS

Patients with COPD (n = 228), enrolled in a multicenter prospective 3-year cohort were classified into four groups based on baseline median FMI and FFMI values. Emphysema assessed as the ratio of low attenuation area to total lung volume (LAA%) on computed tomography, pulmonary function, and health-related quality of life assessed using the St. George's Respiratory Questionnaire (SGRQ) were compared.

RESULTS

The four groups had statistically significant differences in LAA%, pulmonary function, and SGRQ scores. The Low FMI Low FFMI group exhibited the highest LAA%, lowest pulmonary function, and worst SGRQ scores among the four groups. In addition, these differences were consistent over 3 years. Multivariate analysis showed that low FMI was associated with high LAA%, low inspiratory capacity/total lung capacity (IC/TLC), and carbon monoxide transfer coefficient (KCO). In contrast, low FFMI was associated with these factors as well as worse SGRQ scores.

CONCLUSION

FMI and FFMI have different effects on the clinical manifestations of COPD. Both low fat and muscle mass contributed to severe emphysema, whereas only low muscle mass contributed to worse health-related quality of life in patients with COPD.

Use of the Spirometric "Fixed-Ratio" Underdiagnoses COPD in African-Americans in a Longitudinal Cohort Study

BACKGROUND

COPD diagnosis is tightly linked to the fixed-ratio spirometry criteria of FEV1/FVC < 0.7. African-Americans are less often diagnosed with COPD.

OBJECTIVE

Compare COPD diagnosis by fixed-ratio with findings and outcomes by race.

DESIGN

Genetic Epidemiology of COPD (COPDGene) (2007-present), cross-sectional comparing non-Hispanic white (NHW) and African-American (AA) participants for COPD diagnosis, manifestations, and outcomes.

SETTING

Multicenter, longitudinal US cohort study.

PARTICIPANTS

Current or former smokers with ≥ 10-pack-year smoking history enrolled at 21 clinical centers including over-sampling of participants with known COPD and AA. Exclusions were pre-existing non-COPD lung disease, except for a history of asthma.

MEASUREMENTS

Subject diagnosis by conventional criteria. Mortality, imaging, respiratory symptoms, function, and socioeconomic characteristics, including area deprivation index (ADI). Matched analysis (age, sex, and smoking status) of AA vs. NHW within participants without diagnosed COPD (GOLD 0; FEV1 ≥ 80% predicted and FEV1/FVC ≥ 0.7).

RESULTS

Using the fixed ratio, 70% of AA (n = 3366) were classified as non-COPD, versus 49% of NHW (n = 6766). AA smokers were younger (55 vs. 62 years), more often current smoking (80% vs. 39%), with fewer pack-years but similar 12-year mortality. Density distribution plots for FEV1 and FVC raw spirometry values showed disproportionate reductions in FVC relative to FEV1 in AA that systematically led to higher ratios. The matched analysis demonstrated GOLD 0 AA had greater symptoms, worse DLCO, spirometry, BODE scores (1.03 vs 0.54, p < 0.0001), and greater deprivation than NHW.

LIMITATIONS

Lack of an alternative diagnostic metric for comparison.

CONCLUSIONS

The fixed-ratio spirometric criteria for COPD underdiagnosed potential COPD in AA participants when compared to broader diagnostic criteria. Disproportionate reductions in FVC relative to FEV1 leading to higher FEV1/FVC were identified in these participants and associated with deprivation. Broader diagnostic criteria for COPD are needed to identify the disease across all populations.

Changes in Lung Volumes with Spirometric Disease Progression in COPD

Background

Abnormal lung volumes representing air trapping identify the subset of smokers with preserved spirometry who develop spirometric chronic obstructive pulmonary disease (COPD) and adverse outcomes. However, how lung volumes evolve in early COPD as airflow obstruction develops remains unclear.

Methods

To establish how lung volumes change with the development of spirometric COPD, we examined lung volumes from the pulmonary function data (seated posture) available in the U.S. Department of Veterans Affairs electronic health records (n=71,356) and lung volumes measured by computed tomography (supine posture) available from the COPD Genetic Epidemiology (COPDGene®) study (n=7969) and the SubPopulations and InterMediate Outcome Measures In COPD Study (SPIROMICS) (n=2552) cohorts, and studied their cross-sectional distributions and longitudinal changes across the airflow obstruction spectrum. Patients with preserved ratio-impaired spirometry (PRISm) were excluded from this analysis.

Results

Lung volumes from all 3 cohorts showed similar patterns of distributions and longitudinal changes with worsening airflow obstruction. The distributions for total lung capacity (TLC), vital capacity (VC), and inspiratory capacity (IC) and their patterns of change were nonlinear and included different phases. When stratified by airflow obstruction using Global initiative for chronic Obstructive Lung Disease (GOLD) stages, patients with GOLD 1 (mild) COPD had larger lung volumes (TLC, VC, IC) compared to patients with GOLD 0 (smokers with preserved spirometry) or GOLD 2 (moderate) disease. In longitudinal follow-up of baseline GOLD 0 patients who progressed to spirometric COPD, those with an initially higher TLC and VC developed mild obstruction (GOLD 1) while those with an initially lower TLC and VC developed moderate obstruction (GOLD 2).

Conclusions

In COPD, TLC, and VC have biphasic distributions, change in nonlinear fashions as obstruction worsens, and could differentiate those GOLD 0 patients at risk for more rapid spirometric disease progression.

Automated Coronary Artery Calcium and Quantitative Emphysema in Lung Cancer Screening: Association With Mortality, Lung Cancer Incidence, and Airflow Obstruction

PURPOSE

To assess automated coronary artery calcium (CAC) and quantitative emphysema (percentage of low attenuation areas [%LAA]) for predicting mortality and lung cancer (LC) incidence in LC screening. To explore correlations between %LAA, CAC, and forced expiratory value in 1 second (FEV 1 ) and the discriminative ability of %LAA for airflow obstruction.

MATERIALS AND METHODS

Baseline low-dose computed tomography scans of the BioMILD trial were analyzed using an artificial intelligence software. Univariate and multivariate analyses were performed to estimate the predictive value of %LAA and CAC. Harrell C -statistic and time-dependent area under the curve (AUC) were reported for 3 nested models (Model survey : age, sex, pack-years; Model survey-LDCT : Model survey plus %LAA plus CAC; Model final : Model survey-LDCT plus selected confounders). The correlations between %LAA, CAC, and FEV 1 and the discriminative ability of %LAA for airflow obstruction were tested using the Pearson correlation coefficient and AUC-receiver operating characteristic curve, respectively.

RESULTS

A total of 4098 volunteers were enrolled. %LAA and CAC independently predicted 6-year all-cause (Model final hazard ratio [HR], 1.14 per %LAA interquartile range [IQR] increase [95% CI, 1.05-1.23], 2.13 for CAC ≥400 [95% CI, 1.36-3.28]), noncancer (Model final HR, 1.25 per %LAA IQR increase [95% CI, 1.11-1.37], 3.22 for CAC ≥400 [95%CI, 1.62-6.39]), and cardiovascular (Model final HR, 1.25 per %LAA IQR increase [95% CI, 1.00-1.46], 4.66 for CAC ≥400, [95% CI, 1.80-12.58]) mortality, with an increase in concordance probability in Model survey-LDCT compared with Model survey ( P <0.05). No significant association with LC incidence was found after adjustments. Both biomarkers negatively correlated with FEV 1 ( P <0.01). %LAA identified airflow obstruction with a moderate discriminative ability (AUC, 0.738).

CONCLUSIONS

Automated CAC and %LAA added prognostic information to age, sex, and pack-years for predicting mortality but not LC incidence in an LC screening setting. Both biomarkers negatively correlated with FEV 1 , with %LAA enabling the identification of airflow obstruction with moderate discriminative ability.

Deep learning on graphs for multi-omics classification of COPD

Network approaches have successfully been used to help reveal complex mechanisms of diseases including Chronic Obstructive Pulmonary Disease (COPD). However despite recent advances, we remain limited in our ability to incorporate protein-protein interaction (PPI) network information with omics data for disease prediction. New deep learning methods including convolution Graph Neural Network (ConvGNN) has shown great potential for disease classification using transcriptomics data and known PPI networks from existing databases. In this study, we first reconstructed the COPD-associated PPI network through the AhGlasso (Augmented High-Dimensional Graphical Lasso Method) algorithm based on one independent transcriptomics dataset including COPD cases and controls. Then we extended the existing ConvGNN methods to successfully integrate COPD-associated PPI, proteomics, and transcriptomics data and developed a prediction model for COPD classification. This approach improves accuracy over several conventional classification methods and neural networks that do not incorporate network information. We also demonstrated that the updated COPD-associated network developed using AhGlasso further improves prediction accuracy. Although deep neural networks often achieve superior statistical power in classification compared to other methods, it can be very difficult to explain how the model, especially graph neural network(s), makes decisions on the given features and identifies the features that contribute the most to prediction generally and individually. To better explain how the spectral-based Graph Neural Network model(s) works, we applied one unified explainable machine learning method, SHapley Additive exPlanations (SHAP), and identified CXCL11, IL-2, CD48, KIR3DL2, TLR2, BMP10 and several other relevant COPD genes in subnetworks of the ConvGNN model for COPD prediction. Finally, Gene Ontology (GO) enrichment analysis identified glycosaminoglycan, heparin signaling, and carbohydrate derivative signaling pathways significantly enriched in the top important gene/proteins for COPD classifications.

Risks of Mortality and Airflow Limitation in Japanese with Preserved Ratio Impaired Spirometry

RATIONALE

Several Western studies have reported that participants with preserved ratio impaired spirometry (PRISm) have higher risks of airflow limitation (AFL) and death. However, evidence in East Asian populations is limited.

OBJECTIVES

To investigate the relation between PRISm and the risks of death and incident AFL in a Japanese population.

METHODS

A total of 3,032 community-dwelling Japanese participants aged ≥40 years were followed up for a median of 5.3 years by annual spirometry examinations. Participants were classified into lung function categories at baseline as follows: normal spirometry (forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) ≥0.70 and FEV1 ≥80% predicted), PRISm (≥0.70 and <80%), AFL Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 (<0.70 and ≥80%), and AFL GOLD 2-4 (<0.70 and <80%). Hazard ratios (HRs) and their 95% confidence intervals (CIs) were computed using a Cox proportional hazard model.

MEASUREMENTS AND MAIN RESULTS

During the follow-up period, 131 participants died, 22 of whom died from cardiovascular disease, and 218 participants developed AFL. When examining the prognosis of each baseline pulmonary function category, participants with PRISm had higher risks of all-cause death (HR 2.20 [95%CI: 1.35 to 3.59]) and cardiovascular death (HR 4.07 [1.07 to 15.42]) than those with normal spirometry after adjusting for confounders. Moreover, the multivariable-adjusted risk of incident AFL was greater in participants with PRISm than in those with normal spirometry (HR 2.48 [1.83 to 3.36]).

CONCLUSIONS

PRISm was associated with higher risks of all-cause and cardiovascular death and a greater risk of the development of AFL in a Japanese community.

Bronchial wall parameters on CT in healthy never-smoking, smoking, COPD, and asthma populations: a systematic review and meta-analysis

Objective

Research on computed tomography (CT) bronchial parameter measurements shows that there are conflicting results on the values for bronchial parameters in the never-smoking, smoking, asthma, and chronic obstructive pulmonary disease (COPD) populations. This review assesses the current CT methods for obtaining bronchial wall parameters and their comparison between populations.

Methods

A systematic review of MEDLINE and Embase was conducted following PRISMA guidelines (last search date 25th October 2021). Methodology data was collected and summarised. Values of percentage wall area (WA%), wall thickness (WT), summary airway measure (Pi10), and luminal area (Ai) were pooled and compared between populations.

Results

A total of 169 articles were included for methodologic review; 66 of these were included for meta-analysis. Most measurements were obtained from multiplanar reconstructions of segmented airways (93 of 169 articles), using various tools and algorithms; third generation airways in the upper and lower lobes were most frequently studied. COPD (12,746) and smoking (15,092) populations were largest across studies and mostly consisted of men (median 64.4%, IQR 61.5 – 66.1%). There were significant differences between populations; the largest WA% was found in COPD (mean SD 62.93 ± 7.41%, n = 6,045), and the asthma population had the largest Pi10 (4.03 ± 0.27 mm, n = 442). Ai normalised to body surface area (Ai/BSA) (12.46 ± 4 mm², n = 134) was largest in the never-smoking population.

Conclusions

Studies on CT-derived bronchial parameter measurements are heterogenous in methodology and population, resulting in challenges to compare outcomes between studies. Significant differences between populations exist for several parameters, most notably in the wall area percentage; however, there is a large overlap in their ranges.

Key Points

• Diverse methodology in measuring airways contributes to overlap in ranges of bronchial parameters among the never-smoking, smoking, COPD, and asthma populations.

• The combined number of never-smoking participants in studies is low, limiting insight into this population and the impact of participant characteristics on bronchial parameters.

• Wall area percent of the right upper lobe apical segment is the most studied (87 articles) and differentiates all except smoking vs asthma populations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-022-08600-1.

Preserved ratio impaired spirometry is associated with small airway dysfunction and reduced total lung capacity

BACKGROUND

Preserved ratio impaired spirometry (PRISm) refers to decreased forced expiratory volume in 1 s (FEV₁) in the setting of preserved ratio. Little is known about the role of PRISm and its complex relation with small airway dysfunction (SAD) and lung volume. Therefore, we aimed to investigate the associations between PRISm and SAD and lung volume.

METHODS

We conducted a cross-sectional community-dwelling study in China. Demographic data, standard respiratory epidemiology questionnaire, spirometry, impulse oscillometry (IOS) and computed tomography (CT) data were collected. PRISm was defined as post-bronchodilator FEV₁/FVC ≥ 0.70 and FEV₁ < 80% predicted. Spirometry-defined SAD was defined as at least two of three of the post-bronchodilator maximal mid-expiratory flow (MMEF), forced expiratory flow 50% (FEF50), and forced expiratory flow 75% (FEF75) less than 65% of predicted. IOS-defined SAD and CT-defined gas trapping were defined by the fact that the cutoff value of peripheral airway resistance R5-R20 > 0.07 kPa/L/s and LAA_- 856>20%, respectively. Analysis of covariance and logistic regression were used to determine associations between PRISm and SAD and lung volume. We then repeated the analysis with a lower limit of normal definition of spirometry criteria and FVC definition of PRISm. Moreover, we also performed subgroup analyses in ever smoker, never smoker, subjects without airway reversibility or self-reported diagnosed asthma, and subjects with CT-measured total lung capacity ≥70% of predicted.

RESULTS

The final analysis included 1439 subjects. PRISm had higher odds and more severity in spirometry-defined SAD (pre-bronchodilator: odds ratio [OR]: 5.99, 95% confidence interval [95%CI]: 3.87-9.27, P < 0.001; post-bronchodilator: OR: 14.05, 95%CI: 8.88-22.24, P < 0.001), IOS-defined SAD (OR: 2.89, 95%CI: 1.82-4.58, P < 0.001), and CT-air trapping (OR: 2.01, 95%CI: 1.08-3.72, P = 0.027) compared with healthy control after adjustment for confounding factors. CT-measured total lung capacity in PRISm was lower than that in healthy controls (4.15 ± 0.98 vs. 4.78 ± 1.05 L, P < 0.05), after adjustment. These results were robust in repeating analyses and subgroup analyses.

CONCLUSION

Our finding revealed that PRISm was associated with SAD and reduced total lung capacity. Future studies to identify the underlying mechanisms and longitudinal progression of PRISm are warranted.

Different Risks of Mortality and Longitudinal Transition Trajectories in New Potential Subtypes of the Preserved Ratio Impaired Spirometry: Evidence From the English Longitudinal Study of Aging

Background: Preserved ratio impaired spirometry (PRISm), characterized by the decreased forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) with a preserved FEV₁/FVC ratio, is highly prevalent and heterogeneous. We aimed to identify the subtypes of PRISm and examine their differences in clinical characteristics, long-term mortality risks, and longitudinal transition trajectories.

Methods: A total of 6,616 eligible subjects were included from the English longitudinal study of aging. Two subtypes of the PRISm were identified as mild PRISm (either of FEV₁ and FVC <80% predicted value, FEV₁/FVC ≥0.7) and severe PRISm (both FEV₁ and FVC <80% predicted values, FEV₁/FVC ≥0.7). Normal spirometry was defined as both FEV₁ and FVC ≥80% predicted values and FEV₁/FVC ≥0.7. Hazard ratios (HRs) and 95% CIs were calculated by the multiple Cox regression models. Longitudinal transition trajectories were described with repeated spirometry data.

Results: At baseline, severe PRISm had increased respiratory symptoms, including higher percentages of phlegm, wheezing, dyspnea, chronic bronchitis, and emphysema than mild PRISm. After an average of 7.7 years of follow-up, severe PRISm significantly increased the risks of all-cause mortality (HR=1.91, 95%CI = 1.58–2.31), respiratory mortality (HR = 6.02, 95%CI = 2.83–12.84), and CVD mortality (HR = 2.11, 95%CI = 1.42–3.13) compared with the normal spirometry, but no significantly increased risks were found for mild PRISm. In the two longitudinal transitions, mild PRISm tended to transition toward normal spirometry (40.2 and 54.7%), but severe PRISm tended to maintain the status (42.4 and 30.4%) or transition toward Global Initiative for Chronic Obstructive Lung Disease (GOLD)2–4 (28.3 and 33.9%).

Conclusion: Two subtypes of PRISm were identified. Severe PRISm had increased respiratory symptoms, higher mortality risks, and a higher probability of progressing to GOLD2–4 than mild PRISm. These findings provided new evidence for the stratified management of PRISm.

Significance of FEV3/FEV6 in recognition of early airway disease in smokers at risk of development of COPD: Analysis of the SPIROMICS cohort

BACKGROUND

Small airways are known to be affected early in the course of chronic obstructive pulmonary disease (COPD); however, traditional spirometric indices may not accurately identify small airways disease.

RESEARCH QUESTION

Can FEV₃/FEV₆ identify early airflow abnormalities and predict future clinically important respiratory-related outcomes, including development of COPD?

STUDY DESIGN AND METHODS

We included eight hundred thirty-two current and former smokers with post-bronchodilator FEV₁/FVC ≥0.7 from the SPIROMICS cohort. Participants were classified as having a reduced pre-bronchodilator FEV₃/FEV₆ based on lower limit of normal (LLN) values. Repeatability analysis was performed for FEV₃ and FEV₆. Regression modeling was used to evaluate the relationship between baseline FEV₃/FEV₆ and outcome measures including functional small airways disease on thoracic imaging and respiratory exacerbations. Interval censored analysis was used to assess progression to COPD.

RESULTS

FEV₃/FEV₆ <LLN at baseline, defined as reduced compared to FEV₃/FEV₆ ≥LLN, was associated with lower FEV₁, poorer health status (St. George's Respiratory Questionnaire score), more emphysema, and more functional small airways disease on quantitative imaging. FEV₃ and FEV₆ showed excellent agreement between repeat measurements. A reduced FEV₃/FEV₆ was associated with increased odds of a severe respiratory exacerbation within the first year of follow-up and decreased time to first exacerbation. A low FEV₃/FEV₆ was also associated with development of COPD by spirometry (post-bronchodilator FEV₁/FVC <0.7) during study follow-up.

INTERPRETATION

FEV₃/FEV₆ is a routinely available and repeatable spirometric index which can be useful in the evaluation of early airflow obstruction in current and former smokers without COPD. A reduced FEV₃/FEV₆ can identify those at risk for future development of COPD and respiratory exacerbations.

The Heterogeneity of COPD Patients in a Community-Based Practice and the Inadequacy of the Global Initiative for Chronic Obstructive Lung Disease Criteria: A Real-World Experience

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease with differing clinical presentations, which range from an asymptomatic obstructive defect on spirometry to symptomatic normal spirometry. The current standard for diagnosis requires exposure history and the presence of an obstructive ventilatory defect (forced expiratory volume in 1 second [FEV1] to forced vital capacity [FVC] ratio < 70%) on spirometry. In this real-world study, we analyzed patients with physician-diagnosed COPD, described their characteristics, and evaluated the diagnostic sensitivity of Global initiative for chronic Obstructive Lung Disease (GOLD) criteria in this population.

METHODS

We retrospectively analyzed the charts of 2115 patients for eligibility. A total of 1224 patients with physician-diagnosed COPD were selected for this study. The average age was 68.4±11.5 years, with 51% being female. Of the 1224 patients, 18% did not have a history of smoking, 73% had bronchodilator testing, and a significant response of ≥12% was noted in 23% of the COPD patients. Moreover, 43% of the patients met the GOLD criteria for the diagnosis of COPD, whereas the Global Lung Function Initiative (GLI) and lower limit of normal (LLN)criteria were only able to identify 26%.

DISCUSSION

COPD-related mortality is continuing to rise, and it is currently ranked as the third leading cause of death, globally, after cardiovascular diseases and strokes. Despite this alarming statistic, COPD diagnosis is delayed in most cases and can remain undiagnosed, even in smokers. This is partly due to the restrictive GOLD diagnostic criteria, which requires the presence of FEV1/FVC ratio<70.

CONCLUSIONS

The recently proposed COPD Genetic Epidemiology (COPDGene®) 2019 definition for COPD will improve and enhance our ability to diagnose COPD earlier and more accurately.

Association between Comorbidities and Preserved Ratio Impaired Spirometry: Using the Korean National Health and Nutrition Examination Survey IV-VI

BACKGROUND

Preserved ratio impaired spirometry (PRISm) patients have more frequent respiratory symptoms and an increased risk of mortality. However, studies on comorbidities in these patients are lacking.

OBJECTIVES

We investigated the association between PRISm and comorbidities using the Korea National Health and Nutrition Examination Survey (KNHANES).

METHOD

This cross-sectional study included participants aged ≥50 years from the KNHANES (2007-2015). Participants who did not undergo spirometry or performed inadequately were excluded. We classified participants into 3 groups according to spirometry: PRISm (forced expiratory volume in one second [FEV1] /forced vital capacity [FVC] ≥ 0.7 and FEV1 <80%), chronic obstructive pulmonary disease (COPD) (FEV1/ FVC <0.7), and normal. Multivariate logistic regression analyses were used to evaluate the risk of comorbidities in the PRISm group compared to that in the normal group.

RESULT

The study included 17,515 participants: 12,777 (73.0%), 1,563 (8.9%), and 3,175 (18.1%) in normal, PRISm, and COPD groups, respectively. After adjustment for known risk factors of each disease, hypertension (adjusted odds ratio [95% confidence interval]; 1.31 [1.14-1.50]), diabetes (1.51 [1.29-1.78]), hypercholesterolemia (1.20 [1.04-1.37]), obesity (1.31 [1.15-1.48]), ischemic heart disease (1.58 [1.13-2.22]), chronic renal disease (2.31 [1.09-4.88]), and thyroid disease (1.41 [1.09-1.83]) risks were significantly higher in the PRISm group than in the normal group. The average number of comorbidities was 2.45 in the PRISm group, which was higher than that in the normal (2.1) and COPD (2.03) groups (p < 0.05).

CONCLUSION

The number of comorbidities was significantly higher in the PRISm group than in others. Hypertension, diabetes, obesity, ischemic heart disease, chronic renal disease, and thyroid disease were associated with PRISm after adjustment for risk factors.

Lung Cancer Risk Among Patients with Asthma-Chronic Obstructive Pulmonary Disease Overlap

RATIONALE

Chronic obstructive pulmonary disease (COPD) is a well-established independent risk factor for lung cancer, while the literature on the association between asthma and lung cancer is mixed. Whether Asthma COPD Overlap (ACO) is associated with lung cancer has not been studied.

OBJECTIVES

We aimed to compare lung cancer risk among patients with ACO vs. COPD and other conditions associated with airway obstruction.

METHODS

We studied 13,939 smokers from the National Lung Cancer Screening Trial who had baseline spirometry, and utilized spirometric indices and history of childhood asthma to categorize participants into 5 specific airway disease subgroups. We used Poisson regression to compare unadjusted and adjusted lung cancer risk.

RESULTS

The incidence rate of lung cancer per 1,000 person-years was: ACO, 13.2 (95% confidence interval [CI]: 8.1-21.5); COPD, 11.7 (95% CI: 10.5-13.1); asthmatic smokers, 1.8 (95% CI: 0.6-5.4); Global Initiative for Chronic Obstructive Lung Disease-Unclassified, 7.7 (95% CI: 6.4-9.2); and normal-spirometry smokers, 4.1 (95% CI: 3.5-4.8). ACO patients had increased adjusted risk of lung cancer compared to patients with asthma (incidence rate ratio [IRR]: 4.5, 95% CI: 1.3-15.8) and normal spirometry smokers (IRR: 2.3, 95% CI: 1.3-4.2) in models adjusting for other risk factors. Adjusted lung cancer incidence in patients with ACO and COPD were not found to be different (IRR: 1.2, 95% CI 0.7 - 2.1).

CONCLUSIONS

Risk of lung cancer among patients with ACO is similar to those with COPD and higher than other groups of smokers. These results provide further evidence that COPD, with or without a history of childhood asthma, is an independent risk factor for lung cancer.

Discordant Quantitative and Visual CT Assessments in the Diagnosis of Emphysema

Purpose

Visual assessment of computed tomography (CT) of the lung is routinely employed in the diagnosis of emphysema. Quantitative CT (QCT) can complement visual CT but must be well validated. QCT emphysema is defined as ≥5% of lung volume occupied by low attenuation areas ≤-950 Hounsfield units (LAA-950). Discordant visual and QCT assessments are not uncommon. We examined the association between visual and quantitative chest CT evaluation within a large cohort of subjects to identify variables that may explain discordant visual and QCT findings.

Materials and Methods

Volumetric inspiratory CT scans of 1221 subjects enrolled in phase 1 of the COPDGene study conducted at the University of Iowa were reviewed. Participants included never smokers, smokers with normal spirometry, preserved ratio impaired spirometry, and Global Initiative for Obstructive Lung Disease (GOLD) stages I-IV. CT scans were quantitatively scored and visually interpreted by both the COPDGene Imaging Center and the University of Iowa radiologists. Individual-level visual assessments were compared with QCT measurements. Agreement between the two sets of radiologists was calculated using kappa statistic. We assessed variables associated with discordant results using regression methods.

Results

There was a fair agreement for the presence or absence of emphysema between our center's radiologists and QCT (61% concordance, kappa 0.22 [0.17-0.28]). Similar comparisons showed a slight agreement between the COPDGene Imaging Center and QCT (56% concordance, kappa 0.16 [0.11-0.21]), and a moderate agreement between both sets of visual assessments (80% concordance, kappa 0.60 [0.54-0.65]). Current smoking and female gender were significantly associated with QCT-negative but visually detectable emphysema.

Conclusion

The slight-to-fair agreement between visual and quantitative CT assessment of emphysema highlights the need to utilize both modalities for a comprehensive radiologic evaluation. Discordant results may be attributable to one or more factors that warrant further exploration in larger studies.

Clinical Trial Registration

ClinicalTrials.gov Identifier NCT000608764.

Preserved Ratio Impaired Spirometry in a Spirometry Database

BACKGROUND

Spirometry results can yield a diagnosis of normal air flow, air flow obstruction, or preserved ratio impaired spirometry (PRISm), defined as a reduced FEV₁ or FVC in the setting of preserved FEV₁/FVC. Previous studies have estimated the prevalence of PRISm to be 7-12%. Our objective was to examine the prevalence of PRISm in a spirometry database and to identify factors associated with PRISm.

METHODS

We performed a retrospective analysis of 21,870 spirometries; 1,616 were excluded because of missing data or extremes of age, height, or weight. We calculated the prevalence of PRISm in prebronchodilator and postbronchodilator pulmonary function tests. Subsequently, we calculated the prevalence of PRISm by various age, race, body mass index, and diagnosis categories, as well as by gender and smokers versus nonsmokers. Finally, in the subset of the cohort with FEV₁ < lower limit of normal, we performed a multivariable logistic regression analysis to identify factors associated with PRISm.

RESULTS

We identified 18,059 prebronchodilator spirometries, and 22.3% of these yielded a PRISm diagnosis. This prevalence remained stable in postbronchodilator spirometries (17.7%), after excluding earlier pulmonary function tests for subjects with multiple pulmonary function tests (20.7% in prebronchodilator and 24.3% in postbronchodilator), and when we limited the analysis to prebronchodilator spirometries that met American Thoracic Society criteria (20.6%). The PRISm prevalence was higher in subjects 45-60 y old (24.4%) and in males (23.7%) versus females (17.9%). The prevalence rose with body mass index and was higher for those with a referral diagnosis of restrictive lung disease (50%). PRISm prevalence was similar between races and smokers versus nonsmokers. In a multivariable analysis, higher % of predicted FEV₁ (odds ratio 1.51, 95% CI 1.42-1.60), body mass index (odds ratio 1.52, 95% CI 1.39-1.68), and restrictive lung disease (odds ratio 4.32, 95% CI 2.54-7.57) were associated with a diagnosis of PRISm. Smoking was inversely associated (odds ratio 0.55, 95% CI 0.46-0.65) with PRISm.

CONCLUSIONS

In a spirometry database at an academic medical center, the PRISm prevalence was 17-24%, which is higher than previously reported.

Health-Related Quality of Life and Related Factors in Persons with Preserved Ratio Impaired Spirometry: Data from the Korea National Health and Nutrition Examination Surve

Background and Objectives: preserved ratio impaired spirometry (PRISm) is a common spirometric pattern that causes respiratory symptoms, systemic inflammation, and mortality. However, its impact on health-related quality of life (HRQOL) and its associated factors remain unclear. We aimed to identify these HRQOL-related factors and investigate the differences in HROOL between persons with PRISm and those with normal lung function. Materials and Methods: we reviewed the Korea National Health and Nutrition Examination Survey data from 2008 to 2013 to evaluate the HRQOL of persons with PRISm, as measured while using the Euro Quality of Life-5D (EQ-5D) and identify any influencing factors. PRISm was defined as pre-bronchodilator forced expiratory volume in 1 s (FEV₁) <80% predicted and FEV₁ to forced vital capacity (FVC) ratio (FEV₁/FVC) ≥0.7. Individuals with FEV₁ ≥80% predicted and FEV1/FVC ≥0.7 were considered as Controls. Results: of the 27,824 participants over the age of 40 years, 1875 had PRISm. The age- and sex-adjusted EQ-5D index was lower in the PRISm group than in the control group (PRISm, 0.930; control, 0.941; p = 0.005). The participants with PRISm showed a significantly higher prevalence of hypertension (p < 0.001), diabetes (p < 0.001), obesity (p < 0.001), low physical activity (p = 0.001), ever-smoker (p < 0.001), and low income (p = 0.034) than those in the control group. In participants with PRISm, lower EQ-5D index scores were independently associated with old age (p = 0.002), low income (p < 0.001), low education level (p < 0.001), and no economic activity (p < 0.001). Three out of five EQ-5D dimensions (mobility, self-care, and usual activity) indicated a higher proportion of dissatisfied participants in the PRISm group than the control group. Conclusions: the participants with PRISm were identified to have poor HRQOL when compared to those without PRISm. Old age and low socioeconomic status play important roles in HRQOL deterioration in patients with PRISm. By analyzing risk factors that are associated with poor HRQOL, early detection and intervention of PRISm can be done in order to preserve patients’ quality of life.

Impact of the severity of restrictive spirometric pattern on nutrition, physical activity, and quality of life: results from a nationally representative database

The general disease burden associated with the restrictive spirometric pattern (RSP) is substantial. However, the impact of RSP by its severity on general health problems and quality of life has not been well elucidated. This study aimed to analyse nutrition, physical activity, and quality of life in subjects who participated in the Korea National Health and Nutrition Examination Survey 2007–2016 according to severity of RSP. Participants were classified as subjects with normal spirometry, those with mild-to-moderate RSP, and those with severe RSP. Poor quality of life was defined as 25th percentile value on the EuroQoL five dimensions (Eq5D) questionnaire index, i.e., 0.90. This study included 23,615 subjects composed of 20,742 with normal spirometry, 2758 with mild-to-moderate RSP, and 115 with severe RSP. The subjects with severe RSP were more likely to have attained lower education levels, had a lower total caloric intake, had less physical activity, had experienced a higher prevalence of comorbidities, and poorer quality of life than those with normal spirometry (P < 0.001 for all). In multivariable analysis, subjects with a mild-to-moderate RSP and severe RSP were more likely to show decreased total calories (coefficient for change in calorie = − 56.6 kcal and − 286.7 kcal, respectively) than those with normal spirometry; subjects with mild-to-moderate RSP and those with severe RSP were 1.26 times and 1.96 times more likely, respectively, to have a poorer quality of life than those with normal spirometry. Additionally, subjects with mild-to-moderate RSP and those with severe RSP were 0.84 times and 0.36 times less likely, respectively, to have high-intensity physical activity than those with normal spirometry in univariable analysis. The trends of a poorer quality of life and physical activity were only significant in the male subgroups. In conclusion, our study revealed that the severity of general health problems and quality of life reductions are correlated with the severity of RSP, especially in males.

Lung Function Testing in Chronic Obstructive Pulmonary Disease

Lung function testing has undisputed value in the comprehensive assessment and individualized management of chronic obstructive pulmonary disease, a pathologic condition in which a functional abnormality, poorly reversible expiratory airway obstruction, is at the core of its definition. After an overview of the physiologic underpinnings of the disease, the authors outline the role of lung function testing in this disease, including diagnosis, assessment of severity, and indication for and responses to pharmacologic and nonpharmacologic interventions. They discuss the current controversies surrounding test interpretation with these purposes in mind and provide balanced recommendations to optimize their usefulness in different clinical scenarios.

Co-Morbidity Patterns Identified Using Latent Class Analysis of Medications Predict All-Cause Mortality Independent of Other Known Risk Factors: The COPDGene® Study

PURPOSE

Medication patterns include all medications in an individual's clinical profile. We aimed to identify chronic co-morbidity treatment patterns through medication use among COPDGene participants and determine whether these patterns were associated with mortality, acute exacerbations of chronic obstructive pulmonary disease (AECOPD) and quality of life.

MATERIALS AND METHODS

Participants analyzed here completed Phase 1 (P1) and/or Phase 2 (P2) of COPDGene. Latent class analysis (LCA) was used to identify medication patterns and assign individuals into unobserved LCA classes. Mortality, AECOPD, and the St. George's Respiratory Questionnaire (SGRQ) health status were compared in different LCA classes through survival analysis, logistic regression, and Kruskal-Wallis test, respectively.

RESULTS

LCA identified 8 medication patterns from 32 classes of chronic comorbid medications. A total of 8110 out of 10,127 participants with complete covariate information were included. Survival analysis adjusted for covariates showed, compared to a low medication use class, mortality was highest in participants with hypertension+diabetes+statin+antiplatelet medication group. Participants in hypertension+SSRI+statin medication group had the highest odds of AECOPD and the highest SGRQ score at both P1 and P2.

CONCLUSION

Medication pattern can serve as a good indicator of an individual's comorbidities profile and improves models predicting clinical outcomes.

Impact of gastroesophageal reflux on longitudinal lung function and quantitative computed tomography in the COPDGene cohort

Rationale

Gastroesophageal reflux disease (GERD) is a common comorbidity in chronic obstructive pulmonary disease (COPD) and has been associated with increased risk of acute exacerbations, hospitalization, emergency room visits, costs, and quality-of-life impairment. However, it remains unclear whether GERD contributes to the progression of COPD as measured by lung function or computed tomography.

Objective

To determine the impact of GERD on longitudinal changes in lung function and radiographic lung disease in the COPDGene cohort.

Methods

We evaluated 5728 participants in the COPDGene cohort who completed Phase I (baseline) and Phase II (5-year follow-up) visits. GERD status was based on participant-reported physician diagnoses. We evaluated associations between GERD and annualized changes in lung function [forced expired volume in 1 s (FEV₁) and forced vital capacity (FVC)] and quantitative computed tomography (QCT) metrics of airway disease and emphysema using multivariable regression models. These associations were further evaluated in the setting of GERD treatment with proton-pump inhibitors (PPI) and/or histamine-receptor 2 blockers (H₂ blockers).

Results

GERD was reported by 2101 (36.7%) participants at either Phase I and/or Phase II. GERD was not associated with significant differences in slopes of FEV₁ (difference of − 2.53 mL/year; 95% confidence interval (CI), − 5.43 to 0.37) or FVC (difference of − 3.05 mL/year; 95% CI, − 7.29 to 1.19), but the odds of rapid FEV₁ decline of ≥40 mL/year was higher in those with GERD (adjusted odds ratio (OR) 1.20; 95%CI, 1.07 to 1.35). Participants with GERD had increased progression of QCT-measured air trapping (0.159%/year; 95% CI, 0.054 to 0.264), but not other QCT metrics such as airway wall area/thickness or emphysema. Among those with GERD, use of PPI and/or H₂ blockers was associated with faster decline in FEV₁ (difference of − 6.61 mL/year; 95% CI, − 11.9 to − 1.36) and FVC (difference of − 9.26 mL/year; 95% CI, − 17.2 to − 1.28).

Conclusions

GERD was associated with faster COPD disease progression as measured by rapid FEV₁ decline and QCT-measured air trapping, but not by slopes of lung function. The magnitude of the differences was clinically small, but given the high prevalence of GERD, further investigation is warranted to understand the potential disease-modifying role of GERD in COPD pathogenesis and progression.

Clinical trials registration

NCT00608764.

Association of low FVC spirometric pattern with WTC occupational exposures

BACKGROUND

A reduced forced vital capacity without obstruction (low FVC) is the predominant spirometric abnormality reported in workers and volunteers exposed to dust, gases, and fumes at the World Trade Center (WTC) disaster site in 2001-2002. While low FVC has been associated with obesity and metabolic syndrome, its association with WTC occupational exposures has not been demonstrated. We estimated the prevalence of this abnormality and examined its association with WTC exposure level.

METHODS

Longitudinal study of the relation between arrival at the WTC site within 48 h and FVC below the lower limit of normal (FVC < LLN, with normal FEV1/FVC ratio) at any time in 10,284 workers with at least two spirometries between 2002 and 2018. Logistic regression and linear mixed models were used for the multivariable analyses.

RESULTS

The prevalence of low FVC increased from 17.0% (95% CI 15.4%, 18.5%) in June 2003, to 26.4% (95% CI 24.8%, 28.1%) in June 2018, and exceeded at both times that of obstruction. The rate of FVC decline was -43.7 ml/year during the study period. In a multivariable analysis adjusting for obesity, metabolic syndrome indicators, and other factors, early arrival at the WTC disaster site was significantly associated with low FVC, but only among men (ORadj = 1.29, 95% CI 1.17, 1.43). Longitudinal FVC rate of decline did not differ by WTC site arrival time.

CONCLUSIONS

Among WTC workers, the prevalence of low FVC increased over a 16-year period. Early arrival to the WTC disaster site was significantly associated with low FVC in males.

Association between the number and size of intrapulmonary lymph nodes and chronic obstructive pulmonary disease severity

Purpose

One of the main pathophysiological mechanisms of chronic obstructive pulmonary disease is inflammation, which has been associated with lymphadenopathy. Intrapulmonary lymph nodes can be identified on CT as perifissural nodules (PFN). We investigated the association between the number and size of PFNs and measures of COPD severity.

Materials and Methods

CT images were obtained from COPDGene. 50 subjects were randomly selected per GOLD stage (0 to 4), GOLD-unclassified, and never-smoker groups and allocated to either "Healthy," "Mild," or "Moderate/severe" groups. 26/350 (7.4%) subjects had missing images and were excluded. Supported by computer-aided detection, a trained researcher prelocated non-calcified opacities larger than 3 mm in diameter. Included lung opacities were classified independently by two radiologists as either "PFN," "not a PFN," "calcified," or "not a nodule"; disagreements were arbitrated by a third radiologist. Ordinal logistic regression was performed as the main statistical test.

Results

A total of 592 opacities were included in the observer study. A total of 163/592 classifications (27.5%) required arbitration. A total of 17/592 opacities (2.9%) were excluded from the analysis because they were not considered nodular, were calcified, or all three radiologists disagreed. A total of 366/575 accepted nodules (63.7%) were considered PFNs. A maximum of 10 PFNs were found in one image; 154/324 (47.5%) contained no PFNs. The number of PFNs per subject did not differ between COPD severity groups (p = 0.50). PFN short-axis diameter could significantly distinguish between the Mild and Moderate/severe groups, but not between the Healthy and Mild groups (p = 0.021).

Conclusions

There is no relationship between PFN count and COPD severity. There may be a weak trend of larger intrapulmonary lymph nodes among patients with more advanced stages of COPD.

Combined Forced Expiratory Volume in 1 Second and Forced Vital Capacity Bronchodilator Response, Exacerbations, and Mortality in Chronic Obstructive Pulmonary Disease

Rationale: The American Thoracic Society (ATS)/European Respiratory Society defines a positive bronchodilator response (BDR) by a composite of BDR in either forced expiratory volume in 1 second (FEV₁) and/or forced vital capacity (FVC) greater than or equal to 12% and 200 ml (ATS-BDR). We hypothesized that ATS-BDR components would be differentially associated with important chronic obstructive pulmonary disease (COPD) outcomes. Objectives: To examine whether ATS-BDR components are differentially associated with clinical, functional, and radiographic features in COPD. Methods: We included subjects with COPD enrolled in the COPDGene study. In the main analysis, we excluded subjects with self-reported asthma. We categorized BDR into the following: 1) No-BDR, no BDR in either FEV₁ or FVC; 2) FEV₁-BDR, BDR in FEV₁ but no BDR in FVC; 3) FVC-BDR, BDR in FVC but no BDR in FEV₁; and 4) Combined-BDR, BDR in both FEV₁ and FVC. We constructed multivariable logistic, linear, zero-inflated negative binomial, and Cox hazards models to examine the association of BDR categories with symptoms, computed tomography findings, change in FEV₁ over time, respiratory exacerbations, and mortality. We also created models using the ATS BDR definition (ATS-BDR) as the main independent variable. Results: Of 3,340 COPD subjects included in the analysis, 1,083 (32.43%) had ATS-BDR, 182 (5.45%) had FEV₁-BDR, 522 (15.63%) had FVC-BDR, and 379 (11.34%) had Combined-BDR. All BDR categories were associated with FEV₁ decline compared with No-BDR. Compared with No-BDR, both ATS-BDR and Combined-BDR were associated with higher functional residual capacity %predicted, greater internal perimeter of 10 mm, and greater 6-minute-walk distance. In contrast to ATS-BDR, Combined-BDR was independently associated with less emphysema (adjusted beta regression coefficient, -1.67; 95% confidence interval [CI], -2.68 to -0.65; P = 0.001), more frequent respiratory exacerbations (incidence rate ratio, 1.25; 95% CI, 1.03-1.50; P = 0.02) and severe exacerbations (incidence rate ratio, 1.34; 95% CI, 1.05-1.71; P = 0.02), and lower mortality (adjusted hazards ratio, 0.76; 95% CI, 0.58-0.99; P = 0.046). Sensitivity analysis that included subjects with self-reported history of asthma showed similar findings. Conclusions: BDR in both FEV₁ and FVC indicates a COPD phenotype with asthma-like characteristics, and provides clinically more meaningful information than current definitions of BDR.

Quantitative CT Evidence of Airway Inflammation in WTC Workers and Volunteers with Low FVC Spirometric Pattern

BACKGROUND

The most common abnormal spirometric pattern reported in WTC worker and volunteer cohorts has consistently been that of a nonobstructive reduced forced vital capacity (low FVC). Low FVC is associated with obesity, which is highly prevalent in these cohorts. We used quantitative CT (QCT) to investigate proximal and distal airway inflammation and emphysema in participants with stable low FVC pattern.

METHODS

We selected study participants with at least two available longitudinal surveillance spirometries, and a chest CT with QCT measurements of proximal airway inflammation (wall area percent, WAP), end-expiratory air trapping, suggestive of distal airway obstruction (expiratory to inspiratory mean lung attenuation ratio, MLA_EI), and emphysema (percentage of lung volume with attenuation below - 950 HU, LAV%). The comparison groups in multinomial logistic regression models were participants with consistently normal spirometries, and participants with stable fixed obstruction (COPD).

RESULTS

Compared to normal spirometry participants, and after adjusting for age, sex, race/ethnicity, BMI, smoking, and early arrival at the WTC disaster site, low FVC participants had higher WAP (OR_adj 1.24, 95% CI 1.06, 1.45, per 5% unit), suggestive of proximal airway inflammation, but did not differ in MLA_EI, or LAV%. COPD participants did not differ in WAP with the low FVC ones and were more likely to have higher MLA_EI or LAV% than the other two subgroups.

DISCUSSION

WTC workers with spirometric low FVC have higher QCT-measured WAP compared to those with normal spirometries, but did not differ in distal airway and emphysema measurements, independently of obesity, smoking, and other covariates.

Low FVC/TLC in Preserved Ratio Impaired Spirometry (PRISm) is associated with features of and progression to obstructive lung disease

One quarter of individuals with Preserved Ratio Impaired Spirometry (PRISm) will develop airflow obstruction, but there are no established methods to identify these individuals. We examined the utility of FVC/TLC in identifying features of obstructive lung disease. The ratio of post-bronchodilator FVC and TLC_CT from chest CT (FVC/TLC_CT) among current and former smokers with PRISm (FEV₁/FVC ≥ 0.7 and FEV1 < 80%) in COPDGene was used to stratify subjects into quartiles: very high, high, low, and very low. We examined the associations between FVC/TLC_CT quartiles and (1) baseline characteristics, (2) respiratory exacerbations, (3) progression to COPD at 5 years, and (4) all-cause mortality. Among participants with PRISm at baseline (n = 1,131), the very low FVC/TLC_CT quartile was associated with increased gas trapping and emphysema, and higher rates of progression to COPD at 5 years (36% versus 17%; p < 0.001) relative to the very high quartile. The very low FVC/TLC_CT quartile was associated with increased total (IRR = 1.65; 95% CI [1.07–2.54]) and severe (IRR = 2.24; 95% CI [1.29–3.89]) respiratory exacerbations. Mortality was lower in the very high FVC/TLC_CT quartile relative to the other quartiles combined. Reduced FVC/TLC_CT ratio in PRISm is associated with increased symptoms, radiographic emphysema and gas trapping, exacerbations, and progression to COPD.

Genetic Advances in Chronic Obstructive Pulmonary Disease. Insights from COPDGene

Chronic obstructive pulmonary disease (COPD) is a common and progressive disease that is influenced by both genetic and environmental factors. For many years, knowledge of the genetic basis of COPD was limited to Mendelian syndromes, such as alpha-1 antitrypsin deficiency and cutis laxa, caused by rare genetic variants. Over the past decade, the proliferation of genome-wide association studies, the accessibility of whole-genome sequencing, and the development of novel methods for analyzing genetic variation data have led to a substantial increase in the understanding of genetic variants that play a role in COPD susceptibility and COPD-related phenotypes. COPDGene (Genetic Epidemiology of COPD), a multicenter, longitudinal study of over 10,000 current and former cigarette smokers, has been pivotal to these breakthroughs in understanding the genetic basis of COPD. To date, over 20 genetic loci have been convincingly associated with COPD affection status, with additional loci demonstrating association with COPD-related phenotypes such as emphysema, chronic bronchitis, and hypoxemia. In this review, we discuss the contributions of the COPDGene study to the discovery of these genetic associations as well as the ongoing genetic investigations of COPD subtypes, protein biomarkers, and post-genome-wide association study analysis.

Factors influencing decline in quality of life in smokers without airflow obstruction: The COPDGene study

INTRODUCTION

Current and former smokers with normal spirometry and with Preserved Ratio Impaired Spirometry (PRISm) experience respiratory events similar to chronic obstructive pulmonary disease (COPD) exacerbations. Exacerbations significantly reduce quality of life (QoL) in COPD patients however the effect of respiratory exacerbations on QoL in these groups is unknown. We hypothesized that exacerbations and change in exacerbation status would predict QoL decline among normal spirometry and PRISm participants in COPDGene.

METHODS

COPDGene is a multicenter, longitudinal study in the U.S. designed to identify genetic determinants of COPD. We enrolled study subjects in Phase 1 of COPDGene and performed multivariable logistic regression models to determine independent predictors of decline in quality of life [>4 points on the St George's Respiratory Questionnaire (SGRQ)]. Separate analyses were performed for current and former smokers with normal spirometry and PRISm. Frequent exacerbator status was defined by > 2 moderate or >1 severe exacerbations in the year prior to the baseline and year 5 follow-up visits.

RESULTS

Independent predictors of QoL deterioration included current smoking, higher exacerbation frequency, and a change from infrequent to frequent exacerbation status (REF: infrequent to infrequent exacerbation status) in both groups [PRISm (OR = 3.15,95%CI, 1.67-5.94), normal spirometry (OR = 4.72,95%CI, 3.25-6.86)]. A change from frequent to infrequent exacerbation status did not lower the odds of QoL decline in either cohort.

CONCLUSION

Continued smoking and the onset of frequent exacerbations were predictors of QoL decline in smokers with normal spirometry and PRISm. Further studies are needed to identify modifiable factors associated with decline in QoL in smokers.

Ordered multinomial regression for genetic association analysis of ordinal phenotypes at Biobank scale

Logistic regression is the primary analysis tool for binary traits in genome-wide association studies (GWAS). Multinomial regression extends logistic regression to multiple categories. However, many phenotypes more naturally take ordered, discrete values. Examples include (a) subtypes defined from multiple sources of clinical information and (b) derived phenotypes generated by specific phenotyping algorithms for electronic health records (EHR). GWAS of ordinal traits have been problematic. Dichotomizing can lead to a range of arbitrary cutoff values, generating inconsistent, hard to interpret results. Using multinomial regression ignores trait value hierarchy and potentially loses power. Treating ordinal data as quantitative can lead to misleading inference. To address these issues, we analyze ordinal traits with an ordered, multinomial model. This approach increases power and leads to more interpretable results. We derive efficient algorithms for computing test statistics, making ordinal trait GWAS computationally practical for Biobank scale data. Our method is available as a Julia package OrdinalGWAS.jl. Application to a COPDGene study confirms previously found signals based on binary case-control status, but with more significance. Additionally, we demonstrate the capability of our package to run on UK Biobank data by analyzing hypertension as an ordinal trait.

NR, Make BJ, Marchetti N, Martinez FJ, Maselli DJ, Mathews AM, McCormack MC, McDonald MLN, McEvoy CE, Moll M, Molye SS, Murray S, Nath H, Newell Jr. JD, Occhipinti M, Paoletti M, Parekh T, Pistolesi M, Pratte KA, Putcha N, Ragland M, Reinhardt JM, Rennard SI, Rosiello RA, Ross JC, Rossiter HB, Ruczinski I, San Jose Estepar R, Sciurba FC, Sieren JC, Singh H, Soler X, Steiner RM, Strand MJ, Stringer WW, Tal-Singer R, Thomashow B, Vegas Sánchez-Ferrero G, Walsh JW, Wan ES, Washko GR, Michael Wells J, Wendt CH, Westney G, Wilson A, Wise RA, Yen A, Young K, Yun J, Silverman EK, Crapo JD. COPDGene® 2019: Redefining the Diagnosis of Chronic Obstructive Pulmonary Disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) remains a major cause of morbidity and mortality. Present-day diagnostic criteria are largely based solely on spirometric criteria. Accumulating evidence has identified a substantial number of individuals without spirometric evidence of COPD who suffer from respiratory symptoms and/or increased morbidity and mortality. There is a clear need for an expanded definition of COPD that is linked to physiologic, structural (computed tomography [CT]) and clinical evidence of disease. Using data from the COPD Genetic Epidemiology study (COPDGene®), we hypothesized that an integrated approach that includes environmental exposure, clinical symptoms, chest CT imaging and spirometry better defines disease and captures the likelihood of progression of respiratory obstruction and mortality.

METHODS

Four key disease characteristics - environmental exposure (cigarette smoking), clinical symptoms (dyspnea and/or chronic bronchitis), chest CT imaging abnormalities (emphysema, gas trapping and/or airway wall thickening), and abnormal spirometry - were evaluated in a group of 8784 current and former smokers who were participants in COPDGene® Phase 1. Using these 4 disease characteristics, 8 categories of participants were identified and evaluated for odds of spirometric disease progression (FEV1 > 350 ml loss over 5 years), and the hazard ratio for all-cause mortality was examined.

RESULTS

Using smokers without symptoms, CT imaging abnormalities or airflow obstruction as the reference population, individuals were classified as Possible COPD, Probable COPD and Definite COPD. Current Global initiative for obstructive Lung Disease (GOLD) criteria would diagnose 4062 (46%) of the 8784 study participants with COPD. The proposed COPDGene® 2019 diagnostic criteria would add an additional 3144 participants. Under the new criteria, 82% of the 8784 study participants would be diagnosed with Possible, Probable or Definite COPD. These COPD groups showed increased risk of disease progression and mortality. Mortality increased in patients as the number of their COPD characteristics increased, with a maximum hazard ratio for all cause-mortality of 5.18 (95% confidence interval [CI]: 4.15-6.48) in those with all 4 disease characteristics.

CONCLUSIONS

A substantial portion of smokers with respiratory symptoms and imaging abnormalities do not manifest spirometric obstruction as defined by population normals. These individuals are at significant risk of death and spirometric disease progression. We propose to redefine the diagnosis of COPD through an integrated approach using environmental exposure, clinical symptoms, CT imaging and spirometric criteria. These expanded criteria offer the potential to stimulate both current and future interventions that could slow or halt disease progression in patients before disability or irreversible lung structural changes develop.