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.

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.

Eosinophilia and fractional exhaled nitric oxide levels in chronic obstructive lung disease.

INTRODUCTION: COPD is a heterogeneous disorder with varied phenotypes. We aimed to determine the prevalence of asthma history, peripheral eosinophilia and elevated FeNO levels along with the diagnostic utility of peripheral eosinophilia in identifying airway eosinophilic inflammation. METHODS: National Health and Nutrition Examination Survey data were analysed for the study period 2007-2010. Subjects aged ≥40 years with postbronchodilator FEV1/FVC ratio <0.70 were included. Receiver operator curve analysis was performed for sensitivity analysis. A p value of <0.001 is considered statistically significant. RESULTS: A total of 3 110 617 weighted COPD cases were identified; predominantly male (64.4%) and non-Hispanic whites (86.1%). Among our COPD subjects, 14.6% had a history of doctor diagnosed asthma, highest among females and other race Americans. The overall prevalence of peripheral eosinophilia is 36%, 38.3% among COPD subjects with asthma history, and 35.6% among COPD without asthma history. The overall prevalence of elevated FeNO ≥25 ppb is 14.3%; 28.7% among COPD subjects with asthma history and 13.0% among COPD without asthma history. DISCUSSION: The prevalence of FeNO levels ≥25 ppb and peripheral eosinophilia was significantly higher among COPD subjects with asthma compared with COPD without asthma history. Not all COPD subjects with peripheral eosinophilia and elevated FeNO levels have a reported history of asthma. Our study supports clinically phenotyping COPD subjects with eosinophilic inflammation be independent of their asthma history and peripheral eosinophilia can be used as a surrogate marker in resource-limited settings.

Trends and Outcomes in Sepsis Hospitalizations With and Without Atrial Fibrillation: A Nationwide Inpatient Analysis.

OBJECTIVES: Atrial fibrillation is frequently seen in sepsis-related hospitalizations. However, large-scale contemporary data from the United States comparing outcomes among sepsis-related hospitalizations with versus without atrial fibrillation are limited. The aim of our study was to assess the frequency of atrial fibrillation and its impact on outcomes of sepsis-related hospitalizations. DESIGN: Retrospective cohort study. SETTING: The National Inpatient Sample databases (2010-2014). PATIENTS: Primary discharge diagnosis of sepsis with and without atrial fibrillation were identified using prior validated International Classification of Diseases, 9th Edition, Clinical Modification codes. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Overall, 5,808,166 hospitalizations with the primary diagnosis of sepsis, of which 19.4% (1,126,433) were associated with atrial fibrillation. The sepsis-atrial fibrillation cohort consisted of older (median [interquartile range] age of 79 yr [70-86 yr] vs 67 yr [53-79 yr]; p < 0.001) white (80.9% vs 68.8%; p < 0.001) male (51.1% vs 47.5%; p < 0.001) patients with an extended length of stay (median [interquartile range] 6 d [4-11 d] vs 5 d [3-9 d]; p < 0.001) and higher hospitalization charges (median [interquartile range] $44,765 [$23,234-$88,657] vs $35,737 [$18,767-$72,220]; p < 0.001) as compared with the nonatrial fibrillation cohort. The all-cause mortality rate in the sepsis-atrial fibrillation cohort was significantly higher (18.4% and 11.9%; p = 0.001) as compared with those without atrial fibrillation. Although all-cause mortality (20.4% vs 16.6%) and length of stay (median [interquartile range] 7 d [4-11 d] vs 6 d [4-10 d]) decreased between 2010 and 2014, hospitalization charges increased (median [interquartile range] $41,783 [$21,430-$84,465] vs $46,251 [$24,157-$89,995]) in the sepsis-atrial fibrillation cohort. The greatest predictors of mortality in the atrial fibrillation-sepsis cohort were African American race, female gender, advanced age, and the presence of medical comorbidities. CONCLUSIONS: The presence of atrial fibrillation among sepsis-related hospitalizations is a marker of poor prognosis and increased mortality. Although we observed rising trends in sepsis and sepsis-atrial fibrillation-related hospitalizations during the study period, the rate and odds of mortality progressively decreased.

Common and Rare Variants Genetic Association Analysis of Cigarettes per Day Among Ever-Smokers in Chronic Obstructive Pulmonary Disease Cases and Controls.

INTRODUCTION: Cigarette smoking is a major environmental risk factor for many diseases, including chronic obstructive pulmonary disease (COPD). There are shared genetic influences on cigarette smoking and COPD. Genetic risk factors for cigarette smoking in cohorts enriched for COPD are largely unknown. METHODS: We performed genome-wide association analyses for average cigarettes per day (CPD) across the Genetic Epidemiology of COPD (COPDGene) non-Hispanic white (NHW) (n = 6659) and African American (AA) (n = 3260), GenKOLS (the Genetics of Chronic Obstructive Lung Disease) (n = 1671), and ECLIPSE (the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) (n = 1942) cohorts. In addition, we performed exome array association analyses across the COPDGene NHW and AA cohorts. We considered analyses across the entire cohort and stratified by COPD case-control status. RESULTS: We identified genome-wide significant associations for CPD on chromosome 15q25 across all cohorts (lowest p = 1.78 × 10-15), except in the COPDGene AA cohort alone. Previously reported associations on chromosome 19 had suggestive and directionally consistent associations (RAB4, p = 1.95 × 10-6; CYP2A7, p = 7.50 × 10-5; CYP2B6, p = 4.04 × 10-4). When we stratified by COPD case-control status, single nucleotide polymorphisms on chromosome 15q25 were nominally associated with both NHW COPD cases (ß = 0.11, p = 5.58 × 10-4) and controls (ß = 0.12, p = 3.86 × 10-5) For the gene-based exome array association analysis of rare variants, there were no exome-wide significant associations. For these previously replicated associations, the most significant results were among COPDGene NHW subjects for CYP2A7 (p = 5.2 × 10-4). CONCLUSIONS: In a large genome-wide association study of both common variants and a gene-based association of rare coding variants in ever-smokers, we found genome-wide significant associations on chromosome 15q25 with CPD for common variants, but not for rare coding variants. These results were directionally consistent among COPD cases and controls. IMPLICATIONS: We examined both common and rare coding variants associated with CPD in a large population of heavy smokers with and without COPD of NHW and AA descent. We replicated genome-wide significant associations on chromosome 15q25 with CPD for common variants among NHW subjects, but not for rare variants. We demonstrated for the first time that common variants on chromosome 15q25 associated with CPD are similar among COPD cases and controls. Previously reported associations on chromosome 19 showed suggestive and directionally consistent associations among common variants (RAB4, CYP2A7, and CYP2B6) and for rare variants (CYP2A7) among COPDGene NHW subjects. Although the genetic effect sizes for these single nucleotide polymorphisms on chromosome 15q25 are modest, we show that this creates a substantial smoking burden over the lifetime of a smoker.

Smoking duration alone provides stronger risk estimates of chronic obstructive pulmonary disease than pack-years.

BACKGROUND: Cigarette smoking is the strongest risk factor for COPD. Smoking burden is frequently measured in pack-years, but the relative contribution of cigarettes smoked per day versus duration towards the development of structural lung disease, airflow obstruction and functional outcomes is not known. METHODS: We analysed cross-sectional data from a large multicentre cohort (COPDGene) of current and former smokers. Primary outcome was airflow obstruction (FEV1/FVC); secondary outcomes included five additional measures of disease: FEV1, CT emphysema, CT gas trapping, functional capacity (6 min walk distance, 6MWD) and respiratory morbidity (St George's Respiratory Questionnaire, SGRQ). Generalised linear models were estimated to compare the relative contribution of each smoking variable with the outcomes, after adjustment for age, race, sex, body mass index, CT scanner, centre, age of smoking onset and current smoking status. We also estimated adjusted means of each outcome by categories of pack-years and combined groups of categorised smoking duration and cigarettes/day, and estimated linear trends of adjusted means for each outcome by categorised cigarettes/day, smoking duration and pack-years. RESULTS: 10 187 subjects were included. For FEV1/FVC, standardised beta coefficient for smoking duration was greater than for cigarettes/day and pack-years (P<0.001). After categorisation, there was a linear increase in adjusted means FEV1/FVC with increase in pack-years (regression coefficient ß=-0.023±SE0.003; P=0.003) and duration over all ranges of smoking cigarettes/day (ß=-0.041±0.004; P<0.001) but a relatively flat slope for cigarettes/day across all ranges of smoking duration (ß=-0.009±0.0.009; P=0.34). Strength of association of duration was similarly greater than pack-years for emphysema, gas trapping, FEV1, 6MWD and SGRQ. CONCLUSION: Smoking duration alone provides stronger risk estimates of COPD than the composite index of pack-years. TRIAL REGISTRATION NUMBER: Post-results; NCT00608764.

The Value of Biosamples in Smoking Cessation Trials: A Review of Genetic, Metabolomic, and Epigenetic Findings.

Introduction: Human genetic research has succeeded in definitively identifying multiple genetic variants associated with risk for nicotine dependence and heavy smoking. To build on these advances, and to aid in reducing the prevalence of smoking and its consequent health harms, the next frontier is to identify genetic predictors of successful smoking cessation and also of the efficacy of smoking cessation treatments ("pharmacogenomics"). More broadly, additional biomarkers that can be quantified from biosamples also promise to aid "Precision Medicine" and the personalization of treatment, both pharmacological and behavioral. Aims and Methods: To motivate ongoing and future efforts, here we review several compelling genetic and biomarker findings related to smoking cessation and treatment. Results: These Key results involve genetic variants in the nicotinic receptor subunit gene CHRNA5, variants in the nicotine metabolism gene CYP2A6, and the nicotine metabolite ratio. We also summarize reports of epigenetic changes related to smoking behavior. Conclusions: The results to date demonstrate the value and utility of data generated from biosamples in clinical treatment trial settings. This article cross-references a companion paper in this issue that provides practical guidance on how to incorporate biosample collection into a planned clinical trial and discusses avenues for harmonizing data and fostering consortium-based, collaborative research on the pharmacogenomics of smoking cessation. Implications: Evidence is emerging that certain genotypes and biomarkers are associated with smoking cessation success and efficacy of smoking cessation treatments. We review key findings that open potential avenues for personalizing smoking cessation treatment according to an individual's genetic or metabolic profile. These results provide important incentive for smoking cessation researchers to collect biosamples and perform genotyping in research studies and clinical trials.

Leveraging Genomic Data in Smoking Cessation Trials in the Era of Precision Medicine: Why and How.

Implications: This article outlines a framework for the consistent integration of biological data/samples into smoking cessation pharmacotherapy trials, aligned with the objectives of the recently unveiled Precision Medicine Initiative. Our goal is to encourage and provide support for treatment researchers to consider biosample collection and genotyping their existing samples as well as integrating genetic analyses into their study design in order to realize precision medicine in treatment of nicotine dependence.

Biomarkers Predictive of Exacerbations in the SPIROMICS and COPDGene Cohorts.

RATIONALE: Chronic obstructive pulmonary disease exacerbations are associated with disease progression, higher healthcare cost, and increased mortality. Published predictors of future exacerbations include previous exacerbation, airflow obstruction, poor overall health, home oxygen use, and gastroesophageal reflux. OBJECTIVES: To determine the value of adding blood biomarkers to clinical variables to predict exacerbations. METHODS: Subjects from the SPIROMICS (Subpopulations and Intermediate Outcomes Measures in COPD Study) (n = 1,544) and COPDGene (Genetic Epidemiology of COPD) (n = 602) cohorts had 90 plasma or serum candidate proteins measured on study entry using Myriad-RBM multiplex panels. We defined total exacerbations as subject-reported worsening in respiratory health requiring therapy with corticosteroids and/or antibiotics, and severe exacerbations as those leading to hospitalizations or emergency room visits. We assessed retrospective exacerbations during the 12 months before enrollment and then documented prospective exacerbations in each cohort. Exacerbations were modeled for biomarker associations with negative binomial regression including clinical covariates (age, sex, percent predicted FEV1, self-reported gastroesophageal reflux, St. George's Respiratory Questionnaire score, smoking status). We used the Stouffer-Liptak test to combine P values for metaanalysis. MEASUREMENTS AND MAIN RESULTS: Between the two cohorts, 3,471 total exacerbations (1,044 severe) were reported. We identified biomarkers within each cohort that were significantly associated with a history of exacerbation and with a future exacerbation, but there was minimal replication between the cohorts. Although established clinical features were predictive of exacerbations, of the blood biomarkers only decorin and α2-macroglobulin increased predictive value for future severe exacerbations. CONCLUSIONS: Blood biomarkers were significantly associated with the occurrence of exacerbations but were not robust between cohorts and added little to the predictive value of clinical covariates for exacerbations.

Electronic Cigarette Use in US Adults at Risk for or with COPD: Analysis from Two Observational Cohorts.

BACKGROUND: Electronic cigarettes (e-cigarettes) are battery-operated nicotine-delivery devices used by some smokers as a cessation tool as well as by never smokers. OBJECTIVE: To determine the usage of e-cigarettes in older adults at risk for or with chronic obstructive pulmonary disease (COPD). DESIGN: Prospective cohorts. PARTICIPANTS: COPDGene (N = 3536) and SPIROMICS (N = 1060) subjects who were current or former smokers aged 45-80. MAIN MEASURES: Participants were surveyed to determine whether e-cigarette use was associated with longitudinal changes in COPD progression or smoking habits. KEY RESULTS: From 2010 to 2016, participants who had ever used e-cigarettes steadily increased to 12-16%, but from 2014 to 2016 current use was stable at ~5%. E-cigarette use in African-Americans (AA) and whites was similar; however, AA were 1.8-2.9 times as likely to use menthol-flavored e-cigarettes. Current e-cigarette and conventional cigarette users had higher nicotine dependence and consumed more nicotine than those who smoked only conventional cigarettes. E-cigarette users had a heavier conventional cigarette smoking history and worse respiratory health, were less likely to reduce or quit conventional cigarette smoking, had higher nicotine dependence, and were more likely to report chronic bronchitis and exacerbations. Ever e-cigarette users had more rapid decline in lung function, but this trend did not persist after adjustment for persistent conventional cigarette smoking. CONCLUSIONS: E-cigarette use, which is common in adults with or at risk for COPD, was associated with worse pulmonary-related health outcomes, but not with cessation of smoking conventional cigarettes. Although this was an observational study, we find no evidence supporting the use of e-cigarettes as a harm reduction strategy among current smokers with or at risk for COPD.

Impact of Comorbidities Among Medicaid Enrollees With Chronic Obstructive Pulmonary Disease, United States, 2009.

INTRODUCTION: Multimorbidity, the presence of 2 or more chronic conditions, frequently affects people with chronic obstructive pulmonary disease (COPD). Many have high-cost, highly complex conditions that have a substantial impact on state Medicaid programs. We quantified the cost of Medicaid-insured patients with COPD co-diagnosed with other chronic disorders. METHODS: We used nationally representative Medicaid claims data to analyze the impact of comorbidities (other chronic conditions) on the disease burden, emergency department (ED) use, hospitalizations, and total health care costs among 291,978 adult COPD patients. We measured the prevalence of common conditions and their influence on COPD-related and non-COPD-related resource use by using the Elixhauser Comorbidity Index. Elixhauser comorbidity counts were clustered from 0 to 7 or more. We performed multivariable logistic regression to determine the odds of ED visits by Elixhauser scores adjusting for age, sex, race/ethnicity, and residence. RESULTS: Acute care, hospital bed days, and total Medicaid-reimbursed costs increased as the number of comorbidities increased. ED visits unrelated to COPD were more common than visits for COPD, especially in patients self-identified as black or African American (designated black). Hypertension, diabetes, affective disorders, hyperlipidemia, and asthma were the most prevalent comorbid disorders. Substance abuse, congestive heart failure, and asthma were commonly associated with ED visits for COPD. Female sex was associated with COPD-related and non-COPD-related ED visits. CONCLUSION: Comorbidities markedly increased health services use among people with COPD insured with Medicaid, although ED visits in this study were predominantly unrelated to COPD. Achieving excellence in clinical practice with optimal clinical and economic outcomes requires a whole-person approach to the patient and a multidisciplinary health care team.

Sex-specific features of emphysema among current and former smokers with COPD.

Recent studies suggest that males with chronic obstructive pulmonary disease (COPD) have more emphysema than females. It is not known if these differences persist across degrees of COPD severity. Our aim was to identify sex-specific differences in quantitative emphysema within COPD subgroups based on COPD severity.We included non-Hispanic white and African-American subjects from the COPDGene study with at least 10 pack-years of smoking and COPD Global Initiative for Chronic Obstructive Lung Disease (GOLD) spirometry grade II or greater. We examined sex-specific differences in log-transformed emphysema (log per cent low-attenuation area (%LAA)) by GOLD spirometry grade among subjects with early-onset COPD (<55 years old) and advanced emphysema (>25% emphysema).Compared with females, males had higher log %LAA: overall (1.97±1.4 versus 1.69±1.6, ß=0.32 (0.04), p=1.34×10(-14)), and among non-Hispanic white (p=8.37×10(-14)) and African-American subjects (p=0.002). Females with early-onset COPD, severe emphysema and GOLD grade IV COPD had similar emphysema as males, but markedly fewer pack-years smoking (early-onset, p=0.01; severe emphysema and GOLD grade IV, p<0.001).This study identifies subsets of female smokers with COPD who are particularly susceptible to parenchymal destruction.

Moving toward true inclusion of racial/ethnic minorities in federally funded studies. A key step for achieving respiratory health equality in the United States.

A key objective of the 1993 National Institutes of Health (NIH) Revitalization Act was to ensure inclusion of minorities in clinical research. We conducted a literature search for the period from 1993 to 2013 to examine whether racial/ethnic minorities are adequately represented in published research studies of pulmonary diseases, particularly NIH-funded studies. We found a marked underrepresentation of minorities in published clinical research on pulmonary diseases. Over the last 20 years, inclusion of members of racial or ethnic minority groups was reported (in MeSH terms, journal titles, and MEDLINE fields) in less than 5% of all NIH-funded published studies of respiratory diseases. Although a secondary analysis revealed that a larger proportion of NIH-funded studies included any minorities, this proportional increment mostly resulted from studies including relatively small numbers of minorities (which precludes robust race- or ethnic-specific analyses). Underrepresentation or exclusion of minorities from NIH-funded studies is likely due to multiple reasons, including insufficient education and training on designing and implementing population-based studies of minorities, inadequate motivation or incentives to overcome challenges in the recruitment and retention of sufficient numbers of members of racial/ethnic minorities, underrepresentation of minorities among respiratory scientists in academic medical centers, and a dearth of successful partnerships between academic medical centers and underrepresented communities. This problem could be remedied by implementing short-, medium-, and long-term strategies, such as creating incentives to conduct minority research, ensuring fair review of grant applications focusing on minorities, developing the careers of minority scientists, and facilitating and valuing research on minorities by investigators of all backgrounds.

Association Between Expiratory Central Airway Collapse and Respiratory Outcomes Among Smokers.

IMPORTANCE: Central airway collapse greater than 50% of luminal area during exhalation (expiratory central airway collapse [ECAC]) is associated with cigarette smoking and chronic obstructive pulmonary disease (COPD). However, its prevalence and clinical significance are unknown. OBJECTIVE: To determine whether ECAC is associated with respiratory morbidity in smokers independent of underlying lung disease. DESIGN, SETTING, AND PARTICIPANTS: Analysis of paired inspiratory-expiratory computed tomography images from a large multicenter study (COPDGene) of current and former smokers from 21 clinical centers across the United States. Participants were enrolled from January 2008 to June 2011 and followed up longitudinally until October 2014. Images were initially screened using a quantitative method to detect at least a 30% reduction in minor axis tracheal diameter from inspiration to end-expiration. From this sample of screen-positive scans, cross-sectional area of the trachea was measured manually at 3 predetermined levels (aortic arch, carina, and bronchus intermedius) to confirm ECAC (>50% reduction in cross-sectional area). EXPOSURES: Expiratory central airway collapse. MAIN OUTCOMES AND MEASURES: The primary outcome was baseline respiratory quality of life (St George's Respiratory Questionnaire [SGRQ] scale 0 to 100; 100 represents worst health status; minimum clinically important difference [MCID], 4 units). Secondary outcomes were baseline measures of dyspnea (modified Medical Research Council [mMRC] scale 0 to 4; 4 represents worse dyspnea; MCID, 0.7 units), baseline 6-minute walk distance (MCID, 30 m), and exacerbation frequency (events per 100 person-years) on longitudinal follow-up. RESULTS: The study included 8820 participants with and without COPD (mean age, 59.7 [SD, 6.9] years; 4667 [56.7%] men; 4559 [51.7%] active smokers). The prevalence of ECAC was 5% (443 cases). Patients with ECAC compared with those without ECAC had worse SGRQ scores (30.9 vs 26.5 units; P < .001; absolute difference, 4.4 [95% CI, 2.2-6.6]) and mMRC scale scores (median, 2 [interquartile range [IQR], 0-3]) vs 1 [IQR, 0-3]; P < .001]), but no significant difference in 6-minute walk distance (399 vs 417 m; absolute difference, 18 m [95% CI, 6-30]; P = .30), after adjustment for age, sex, race, body mass index, forced expiratory volume in the first second, pack-years of smoking, and emphysema. On follow-up (median, 4.3 [IQR, 3.2-4.9] years), participants with ECAC had increased frequency of total exacerbations (58 vs 35 events per 100 person-years; incidence rate ratio [IRR], 1.49 [95% CI, 1.29-1.72]; P < .001) and severe exacerbations requiring hospitalization (17 vs 10 events per 100 person-years; IRR, 1.83 [95% CI, 1.51-2.21]; P < .001). CONCLUSIONS AND RELEVANCE: In a cross-sectional analysis of current and former smokers, the presence of ECAC was associated with worse respiratory quality of life. Further studies are needed to assess long-term associations with clinical outcomes.

Smoking-Associated Site-Specific Differential Methylation in Buccal Mucosa in the COPDGene Study.

DNA methylation is a complex, tissue-specific phenomenon that can reflect both endogenous factors and exogenous exposures. Buccal brushings represent an easily accessible source of DNA, which may be an appropriate surrogate tissue in the study of environmental exposures and chronic respiratory diseases. Buccal brushings were obtained from a subset of current and former smokers from the COPDGene study. Genome-wide DNA methylation data were obtained in the discovery cohort (n = 82) using the Illumina HumanMethylation450K array. Empirical Bayes methods were used to test for differential methylation by current smoking status at 468,219 autosomal CpG sites using linear models adjusted for age, sex, and race. Pyrosequencing was performed in a nonoverlapping replication cohort (n = 130). Current smokers were significantly younger than former smokers in both the discovery and replication cohorts. Seven CpG sites were associated with current smoking at a false discovery rate less than 0.05 in the discovery cohort. Six of the seven significant sites were pyrosequenced in the replication cohort; five CpG sites, including sites annotated to CYP1B1 and PARVA, were replicated. Correlations between cumulative smoke exposure and time since smoking cessation were observed in a subset of the significantly associated CpG sites. A significant correlation between reduced lung function and increased radiographic emphysema with methylation at cg02162897 (CYP1B1) was observed among female subjects. Site-specific methylation of DNA isolated from buccal mucosa is associated with exposure to cigarette smoke, and may provide insights into the mechanisms underlying differential susceptibility toward the development of smoking-related chronic respiratory diseases.

Admixture mapping identifies a quantitative trait locus associated with FEV1/FVC in the COPDGene Study.

African Americans are admixed with genetic contributions from European and African ancestral populations. Admixture mapping leverages this information to map genes influencing differential disease risk across populations. We performed admixture and association mapping in 3,300 African American current or former smokers from the COPDGene Study. We analyzed estimated local ancestry and SNP genotype information to identify regions associated with FEV1 /FVC, the ratio of forced expiratory volume in one second to forced vital capacity, measured by spirometry performed after bronchodilator administration. Global African ancestry inversely associated with FEV1 /FVC (P = 0.035). Genome-wide admixture analysis, controlling for age, gender, body mass index, current smoking status, pack-years smoked, and four principal components summarizing the genetic background of African Americans in the COPDGene Study, identified a region on chromosome 12q14.1 associated with FEV1 /FVC (P = 2.1 × 10(-6) ) when regressed on local ancestry. Allelic association in this region of chromosome 12 identified an intronic variant in FAM19A2 (rs348644) as associated with FEV1 /FVC (P = 1.76 × 10(-6) ). By combining admixture and association mapping, a marker on chromosome 12q14.1 was identified as being associated with reduced FEV1 /FVC ratio among African Americans in the COPDGene Study.

A genome-wide association study identifies risk loci for spirometric measures among smokers of European and African ancestry.

BACKGROUND: Pulmonary function decline is a major contributor to morbidity and mortality among smokers. Post bronchodilator FEV1 and FEV1/FVC ratio are considered the standard assessment of airflow obstruction. We performed a genome-wide association study (GWAS) in 9919 current and former smokers in the COPDGene study (6659 non-Hispanic Whites [NHW] and 3260 African Americans [AA]) to identify associations with spirometric measures (post-bronchodilator FEV1 and FEV1/FVC). We also conducted meta-analysis of FEV1 and FEV1/FVC GWAS in the COPDGene, ECLIPSE, and GenKOLS cohorts (total n = 13,532). RESULTS: Among NHW in the COPDGene cohort, both measures of pulmonary function were significantly associated with SNPs at the 15q25 locus [containing CHRNA3/5, AGPHD1, IREB2, CHRNB4] (lowest p-value = 2.17 × 10(-11)), and FEV1/FVC was associated with a genomic region on chromosome 4 [upstream of HHIP] (lowest p-value = 5.94 × 10(-10)); both regions have been previously associated with COPD. For the meta-analysis, in addition to confirming associations to the regions near CHRNA3/5 and HHIP, genome-wide significant associations were identified for FEV1 on chromosome 1 [TGFB2] (p-value = 8.99 × 10(-9)), 9 [DBH] (p-value = 9.69 × 10(-9)) and 19 [CYP2A6/7] (p-value = 3.49 × 10(-8)) and for FEV1/FVC on chromosome 1 [TGFB2] (p-value = 8.99 × 10(-9)), 4 [FAM13A] (p-value = 3.88 × 10(-12)), 11 [MMP3/12] (p-value = 3.29 × 10(-10)) and 14 [RIN3] (p-value = 5.64 × 10(-9)). CONCLUSIONS: In a large genome-wide association study of lung function in smokers, we found genome-wide significant associations at several previously described loci with lung function or COPD. We additionally identified a novel genome-wide significant locus with FEV1 on chromosome 9 [DBH] in a meta-analysis of three study populations.