There is no clinically useful score to predict chronic obstructive pulmonary disease (COPD) exacerbations. We aimed to derive this by analyzing data from three existing COPD clinical trials of budesonide/formoterol, formoterol, or placebo in patients with moderate-to-very-severe COPD and a history of exacerbations in the previous year.
Predictive variables were selected using Cox regression for time to first severe COPD exacerbation. We determined absolute risk estimates for an exacerbation by identifying variables in a binomial model, adjusting for observation time, study, and treatment. The model was further reduced to clinically useful variables and the final regression coefficients scaled to obtain risk scores of 0–100 to predict an exacerbation within 6 months. Receiver operating characteristic (ROC) curves and the corresponding C-index were used to investigate the discriminatory properties of predictive variables.
The best predictors of an exacerbation in the next 6 months were more COPD maintenance medications prior to the trial, higher mean daily reliever use, more exacerbations during the previous year, lower forced expiratory volume in 1 second/forced vital capacity ratio, and female sex. Using these risk variables, we developed a score to predict short-term (6-month) risk of COPD exacerbations (SCOPEX). Budesonide/formoterol reduced future exacerbation risk more than formoterol or as-needed short-acting β2-agonist (salbutamol).
SCOPEX incorporates easily identifiable patient characteristics and can be readily applied in clinical practice to target therapy to reduce COPD exacerbations in patients at the highest risk.
chronic obstructive pulmonary disease; exacerbation; model; predictor; inhaled corticosteroids; bronchodilators
Individuals with COPD and asthma are an important but poorly characterized group. The genetic determinants of COPD-asthma overlap have not been studied.
Identify clinical features and genetic risk factors for COPD-asthma overlap.
Subjects were current or former smoking non-Hispanic whites (NHW) or African-Americans (AA) with COPD. Overlap subjects reported a history of physician-diagnosed asthma before the age of 40. We compared clinical and radiographic features between COPD and overlap subjects. We performed genome-wide association studies (GWAS) in the NHW and AA populations, and combined these results in a meta-analysis.
More women and African Americans reported a history of asthma. Overlap subjects had more severe and more frequent respiratory exacerbations, less emphysema, and greater airway wall thickness compared to subjects with COPD alone. The NHW GWAS identified SNPs in CSMD1 (rs11779254, P=1.57×10−6) and SOX5(rs59569785, P=1.61×10−6) and the meta-analysis identified SNPs in the gene GPR65 (rs6574978, P=1.18×10−7) associated with COPD-asthma overlap.
Overlap subjects have more exacerbations, less emphysema and more airway disease for any degree of lung function impairment compared to COPD alone. We identified novel genetic variants associated with this syndrome. COPD-asthma overlap is an important syndrome and may require distinct clinical management.
Chronic obstructive pulmonary disease (COPD) is a major cause of
morbidity and mortality, yet research suggests this disease is greatly
underdiagnosed. This literature review sought to summarize the most common
and significant variables associated with case-finding or missed cases of
COPD to inform more effective and efficient detection of high-risk COPD
patients in primary care.
PubMed and EMBASE were searched for articles describing case-finding
and epidemiologic research to detect or characterize new cases of COPD.
International studies in primary and non-primary care settings, published in
English from 2002–2014, were eligible for inclusion. Studies related
to risk factors for development of COPD were excluded.
Of the 33 studies identified and reviewed, 21 were case-finding or
screening and 12 were epidemiological, including cross-sectional,
longitudinal, and retrospective designs. A range of variables were
identified within and across studies. Variables common to both screening and
epidemiological studies included age, smoking status, and respiratory
symptoms. Seven significant predictors from epidemiologic studies did not
appear in screening tools. No studies targeted discovery of higher risk
patients such as those with reduced lung function or risks for
Variables used to identify new cases of COPD or differentiate COPD
cases and non-cases are wide- ranging, (from sociodemographic to
self-reported health or health history variables), providing insight into
important factors for case identification. Further research is underway to
develop and test the best, smallest variable set that can be used as a
screening tool to identify people with undiagnosed, high-risk COPD in
chronic obstructive pulmonary disease; primary care; screening; literature review
There is notable heterogeneity in the clinical presentation of patients with COPD. To characterize this heterogeneity, we sought to identify subgroups of smokers by applying cluster analysis to data from the COPDGene Study.
We applied a clustering method, k-means, to data from 10,192 smokers in the COPDGene Study. After splitting the sample into a training and validation set, we evaluated three sets of input features across a range of k (user-specified number of clusters). Stable solutions were tested for association with four COPD-related measures and five genetic variants previously associated with COPD at genome-wide significance. The results were confirmed in the validation set.
We identified four clusters that can be characterized as 1) relatively resistant smokers (i.e. no/mild obstruction and minimal emphysema despite heavy smoking), 2) mild upper zone emphysema predominant, 3) airway disease predominant, and 4) severe emphysema. All clusters are strongly associated with COPD-related clinical characteristics, including exacerbations and dyspnea (p<0.001). We found strong genetic associations between the mild upper zone emphysema group and rs1980057 near HHIP, and between the severe emphysema group and rs8034191 in the chromosome 15q region (p<0.001). All significant associations were replicated at p<0.05 in the validation sample (12/12 associations with clinical measures and 2/2 genetic associations).
Cluster analysis identifies four subgroups of smokers that show robust associations with clinical characteristics of COPD and known COPD-associated genetic variants.
Nighttime symptoms can negatively impact the quality of life of patients with chronic obstructive pulmonary disease (COPD). The Nighttime Symptoms of COPD Instrument (NiSCI) was designed to measure the occurrence and severity of nighttime symptoms in patients with COPD, the impact of symptoms on nighttime awakenings, and rescue medication use. The objective of this study was to explore item reduction, inform scoring recommendations, and evaluate the psychometric properties of the NiSCI.
COPD patients participating in a Phase III clinical trial completed the NiSCI daily. Item analyses were conducted using weekly mean and single day scores. Descriptive statistics (including percentage of respondents at floor/ceiling and inter-item correlations), factor analyses, and Rasch model analyses were conducted to examine item performance and scoring. Test–retest reliability was assessed for the final instrument using the intraclass correlation coefficient (ICC). Correlations with assessments conducted during study visits were used to evaluate convergent and known-groups validity.
Data from 1,663 COPD patients aged 40–93 years were analyzed. Item analyses supported the generation of four scores. A one-factor structure was confirmed with factor analysis and Rasch analysis for the symptom severity score. Test–retest reliability was confirmed for the six-item symptom severity (ICC, 0.85), number of nighttime awakenings (ICC, 0.82), and rescue medication (ICC, 0.68) scores. Convergent validity was supported by significant correlations between the NiSCI, St George’s Respiratory Questionnaire, and Exacerbations of Chronic Obstructive Pulmonary Disease Tool-Respiratory Symptoms scores.
The results suggest that the NiSCI can be used to determine the severity of nighttime COPD symptoms, the number of nighttime awakenings due to COPD symptoms, and the nighttime use of rescue medication. The NiSCI is a reliable and valid instrument to evaluate these concepts in COPD patients in clinical trials and clinical practice. Scoring recommendations and steps for further research are discussed.
nighttime symptoms; PRO; psychometric validation; COPD
Rationale: FVC is a difficult maneuver for many patients, and forced expiratory volume in 6 seconds (FEV6) has been proposed as a surrogate for FVC for the diagnosis of chronic obstructive pulmonary disease (COPD). Previous studies have performed head-to-head comparisons of these thresholds but did not examine their relationships with structural lung disease, symptoms, or exacerbations.
Objectives: To compare FEV1/FEV6 with FEV1/FVC in the diagnosis of COPD-related morbidity and structural lung disease as assessed by CT.
Methods: We analyzed data from a large multicenter cohort study (COPDGene) that included current and former smokers (age 45–80 yr). Accuracy and concordance between the two ratios in diagnosing structural COPD was compared using CT measures of emphysema and airway disease and COPD-related morbidity to assess how the two ratios compare in defining disease.
Results: A total of 10,018 subjects were included. FEV1/FEV6 showed excellent accuracy in diagnosing airflow obstruction using FEV1/FVC < 0.70 as a reference (area under curve, 0.99; 95% confidence interval [CI], 0.989–0.992; P < 0.001). FEV1/FEV6 < 0.73 had the best sum of sensitivity (92.1%; 95% CI, 90.8–92.4) and specificity (97.3%; 95% CI, 97.3–98.1). There was excellent agreement between the two diagnostic cutoffs (κ = 0.90; 95% CI, 0.80–0.91; P < 0.001). In comparison with control subjects and those positive by FEV1/FVC alone, subjects positive by FEV1/FEV6 alone had greater gas trapping and airway wall thickness, worse functional capacity, and a greater number of exacerbations on follow-up. These relationships held true when disease definitions were made using the lower limits of normal.
Conclusions: FEV1/FEV6 can be substituted for FEV1/FVC in diagnosing airflow obstruction and may better predict COPD-related pathology and morbidity.
FEV1/FEV6; spirometry; COPD
The genetic risk factors for susceptibility to chronic obstructive
pulmonary disease (COPD) are still largely unknown. Additional genetic
variants are likely to be identified by genome-wide association studies in
larger cohorts or specific subgroups.
Genome-wide association analysis in COPDGene (non-Hispanic whites and
African-Americans) was combined with existing data from the ECLIPSE,
NETT/NAS, and GenKOLS (Norway) studies. Analyses were performed both using
all moderate-to-severe cases and the subset of severe cases. Top loci not
previously described as genome-wide significant were genotyped in the ICGN
study, and results combined in a joint meta-analysis.
Analysis of a total of 6,633 moderate-to-severe cases and 5,704
controls confirmed association at three known loci:
CHRNA3/CHRNA5/IREB2, FAM13A, and HHIP
(10−12 < P < 10−14),
and also showed significant evidence of association at a novel locus near
RIN3 (overall P, including ICGN =
5•4×10−9). In the severe COPD analysis
(n=3,497), the effects at two of three previously described loci were
significantly stronger; we also identified two additional loci previously
reported to affect gene expression of MMP12 and
TGFB2 (overall P = 2•6x10−9
and 8•3×10−9). RIN3 and
TGFB2 expression levels were reduced in a set of Lung
Tissue Research Consortium COPD lung tissue samples compared with
In a genome-wide study of COPD, we confirmed associations at three
known loci and found additional genome-wide significant associations with
moderate-to-severe COPD near RIN3 and with severe COPD near
MMP12 and TGFB2. Genetic variants,
apart from alpha-1 antitrypsin deficiency, increase the risk of COPD. Our
analysis of severe COPD suggests additional genetic variants may be
identified by focusing on this subgroup.
National Heart, Lung, and Blood Institute; the COPD Foundation
through contributions from AstraZeneca, Boehringer Ingelheim, Novartis, and
Sepracor; GlaxoSmithKline; Centers for Medicare and Medicaid Services;
Agency for Healthcare Research and Quality; US Department of Veterans
COPD patients have a great burden of comorbidity. However, it is not well established whether this is due to shared risk factors such as smoking, if they impact patients exercise capacity and quality of life, or whether there are racial disparities in their impact on COPD.
We analyzed data from 10,192 current and ex-smokers with (cases) and without COPD (controls) from the COPDGene® cohort to establish risk for COPD comorbidities adjusted for pertinent covariates. In adjusted models, we examined comorbidities prevalence and impact in African-Americans (AA) and Non-Hispanic Whites (NHW).
Comorbidities are more common in COPD compared to those with normal spirometry (controls), and the risk persists after adjustments for covariates including pack-years smoked. After adjustment for confounders, eight conditions were independently associated with worse exercise capacity, quality of life and dyspnea. There were racial disparities in the impact of comorbidities on exercise capacity, dyspnea and quality of life, presence of osteoarthritis and gastroesophageal reflux disease having a greater negative impact on all three outcomes in AAs than NHWs (p<0.05 for all interaction terms).
Individuals with COPD have a higher risk for comorbidities than controls, an important finding shown for the first time comprehensively after accounting for confounders. Individual comorbidities are associated with worse exercise capacity, quality of life, and dyspnea, in African-Americans compared to non-Hispanic Whites.
COPD; Comorbidities; Race
Assessment of patients with chronic obstructive pulmonary disease (COPD) is important to establish an accurate diagnosis, assist in making therapeutic decisions, measuring outcomes for clinical and research purposes, and determining prognosis. Chest computed tomography (CT) scans are useful in patients who present with airflow limitation and clinical features suggestive of COPD but in whom other diagnoses are being considered. In such cases, a chest CT may indicate another diagnosis. The amount and distribution of emphysema can identify outcomes from lung volume reduction surgery, and chest CT scans are mandatory in assessment of patients for this surgery. Quantitative parameters from chest CT scans have been used to define longitudinal progression of disease. Assessment of patients with COPD for both clinical and research purposes should incorporate a variety of different outcomes. There are outcome measures that have been successfully incorporated in large clinical trials, and the design and outcomes of these trials can be used to plan future clinical investigations in COPD.
chest computed tomography scan; chronic obstructive pulmonary disease; outcomes; health status; exercise capacity
Chronic obstructive pulmonary disease (COPD) has been classically divided into blue bloaters and pink puffers. The utility of these clinical subtypes is unclear. However, the broader distinction between airway-predominant and emphysema-predominant COPD may be clinically relevant. The objective was to define clinical features of emphysema-predominant and non-emphysematous COPD patients.
Current and former smokers from the Genetic Epidemiology of COPD Study (COPDGene) had chest computed tomography (CT) scans with quantitative image analysis. Emphysema-predominant COPD was defined by low attenuation area at -950 Hounsfield Units (LAA-950) ≥10%. Non-emphysematous COPD was defined by airflow obstruction with minimal to no emphysema (LAA-950 < 5%).
Out of 4197 COPD subjects, 1687 were classified as emphysema-predominant and 1817 as non-emphysematous; 693 had LAA-950 between 5–10% and were not categorized. Subjects with emphysema-predominant COPD were older (65.6 vs 60.6 years, p < 0.0001) with more severe COPD based on airflow obstruction (FEV1 44.5 vs 68.4%, p < 0.0001), greater exercise limitation (6-minute walk distance 1138 vs 1331 ft, p < 0.0001) and reduced quality of life (St. George’s Respiratory Questionnaire score 43 vs 31, p < 0.0001). Self-reported diabetes was more frequent in non-emphysematous COPD (OR 2.13, p < 0.001), which was also confirmed using a strict definition of diabetes based on medication use. The association between diabetes and non-emphysematous COPD was replicated in the ECLIPSE study.
Non-emphysematous COPD, defined by airflow obstruction with a paucity of emphysema on chest CT scan, is associated with an increased risk of diabetes. COPD patients without emphysema may warrant closer monitoring for diabetes, hypertension, and hyperlipidemia and vice versa.
Clinicaltrials.gov identifiers: COPDGene NCT00608764, ECLIPSE NCT00292552.
Electronic supplementary material
The online version of this article (doi:10.1186/1471-2466-14-164) contains supplementary material, which is available to authorized users.
Airway disease; CT scan; Diabetes mellitus; Emphysema; Spirometry
Bronchodilator responsiveness (BDR) is a common but variable phenomenon in COPD. The CT characteristics of airway dimensions that differentiate COPD subjects with BDR from those without BDR have not been well described. We aimed to assess airway dimensions in COPD subjects with and without BDR.
We analyzed subjects with GOLD 1–4 disease in the COPDGene® study who had CT airway analysis. We divided patients into two groups: BDR + (post bronchodilator ΔFEV1 ≥ 10%) and BDR-(post bronchodilator ΔFEV1 < 10%). The mean wall area percent (WA%) of six segmental bronchi in each subject was quantified using VIDA. Using 3D SLICER, airway wall thickness was also expressed as the square root wall area of an airway of 10 mm (Pi10) and 15 mm (Pi15) diameter. %Emphysema and %gas trapping were also calculated.
2355 subjects in the BDR-group and 1306 in the BDR + group formed our analysis. The BDR + group had a greater Pi10, Pi15, and mean segmental WA% compared to the BDR-group. In multivariate logistic regression using gender, race, current smoking, history of asthma, %emphysema, %gas trapping, %predicted FEV1, and %predicted FVC, airway wall measures remained independent predictors of BDR. Using a threshold change in FEV1 ≥ 15% and FEV1 ≥ 12% and 200 mL to divide patients into groups, the results were similar.
BDR in COPD is independently associated with CT evidence of airway pathology. This study provides us with greater evidence of changes in lung structure that correlate with physiologic manifestations of airflow obstruction in COPD.
Bronchodilator responsiveness; Airway wall thickness; Chronic obstructive pulmonary disease; Airflow obstruction
Preserved Ratio Impaired Spirometry (PRISm), defined as a reduced FEV1 in the setting of a preserved FEV1/FVC ratio, is highly prevalent and is associated with increased respiratory symptoms, systemic inflammation, and mortality. Studies investigating quantitative chest tomographic features, genetic associations, and subtypes in PRISm subjects have not been reported.
Data from current and former smokers enrolled in COPDGene (n = 10,192), an observational, cross-sectional study which recruited subjects aged 45–80 with ≥10 pack years of smoking, were analyzed. To identify epidemiological and radiographic predictors of PRISm, we performed univariate and multivariate analyses comparing PRISm subjects both to control subjects with normal spirometry and to subjects with COPD. To investigate common genetic predictors of PRISm, we performed a genome-wide association study (GWAS). To explore potential subgroups within PRISm, we performed unsupervised k-means clustering.
The prevalence of PRISm in COPDGene is 12.3%. Increased dyspnea, reduced 6-minute walk distance, increased percent emphysema and decreased total lung capacity, as well as increased segmental bronchial wall area percentage were significant predictors (p-value <0.05) of PRISm status when compared to control subjects in multivariate models. Although no common genetic variants were identified on GWAS testing, a significant association with Klinefelter’s syndrome (47XXY) was observed (p-value < 0.001). Subgroups identified through k-means clustering include a putative “COPD-subtype”, “Restrictive-subtype”, and a highly symptomatic “Metabolic-subtype”.
PRISm subjects are clinically and genetically heterogeneous. Future investigations into the pathophysiological mechanisms behind and potential treatment options for subgroups within PRISm are warranted.
Clinicaltrials.gov Identifier: NCT000608764.
Electronic supplementary material
The online version of this article (doi:10.1186/s12931-014-0089-y) contains supplementary material, which is available to authorized users.
Spirometry; Restriction; Lung diseases; Smoking
Chronic bronchitis (CB) has been related to poor outcomes in Chronic Obstructive Pulmonary Disease (COPD). From a clinical standpoint, we have shown that subjects with CB in a group with moderate to severe airflow obstruction were younger, more likely to be current smokers, male, Caucasian, had worse health related quality of life, more dyspnea, and increased exacerbation history compared to those without CB. We sought to further refine our clinical characterization of chronic bronchitics in a larger cohort and analyze the CT correlates of CB in COPD subjects. We hypothesized that COPD patients with CB would have thicker airways and a greater history of smoking, acute bronchitis, allergic rhinitis, and occupational exposures compared to those without CB.
We divided 2703 GOLD 1–4 subjects in the Genetic Epidemiology of COPD (COPDGene®) Study into two groups based on symptoms: chronic bronchitis (CB+, n = 663, 24.5%) and no chronic bronchitis (CB-, n = 2040, 75.5%). Subjects underwent extensive clinical characterization, and quantitative CT analysis to calculate mean wall area percent (WA%) of 6 segmental airways was performed using VIDA PW2 (http://www.vidadiagnostics.com). Square roots of the wall areas of bronchi with internal perimeters 10 mm and 15 mm (Pi10 and Pi15, respectively), % emphysema, %gas trapping, were calculated using 3D Slicer (http://www.slicer.org).
There were no differences in % emphysema (11.4 ± 12.0 vs. 12.0 ± 12.6%, p = 0.347) or % gas trapping (35.3 ± 21.2 vs. 36.3 ± 20.6%, p = 0.272) between groups. Mean segmental WA% (63.0 ± 3.2 vs. 62.0 ± 3.1%, p < 0.0001), Pi10 (3.72 ± 0.15 vs. 3.69 ± 0.14 mm, p < 0.0001), and Pi15 (5.24 ± 0.22 vs. 5.17 ± 0.20, p < 0.0001) were greater in the CB + group. Greater percentages of gastroesophageal reflux, allergic rhinitis, histories of asthma and acute bronchitis, exposures to dusts and occupational exposures, and current smokers were seen in the CB + group. In multivariate binomial logistic regression, male gender, Caucasian race, a lower FEV1%, allergic rhinitis, history of acute bronchitis, current smoking, and increased airway wall thickness increased odds for having CB.
Histories of asthma, allergic rhinitis, acute bronchitis, current smoking, a lower FEV1%, Caucasian race, male gender, and increased airway wall thickness are associated with CB. These data provide clinical and radiologic correlations to the clinical phenotype of CB.
Chronic bronchitis; Chronic obstructive pulmonary disease; Airway thickening; Asthma
Smokers who have severe alpha-1 antitrypsin deficiency (AATD) are at risk for developing COPD earlier in life than smokers without AATD, and are likely to experience challenges adjusting to their illness because they are in a highly productive life stage when they are diagnosed with COPD. This study examined whether individuals with AATD-associated COPD differ from individuals with non-AATD COPD with regard to depression, anxiety, dyspnea, and health-related quality of life (HRQL). Cross-sectional data were collected via self-report questionnaires completed by 480 individuals with non-AATD COPD and 578 individuals with AATD-associated COPD under protocols with IRB approval. Multiple linear regression models were used to test whether individuals with non-AATD COPD differed from individuals with AATD-associated COPD with regard to depression, anxiety, dyspnea, and HRQL. All models adjusted for demographic and health characteristics. Individuals with AATD-associated COPD did not report more symptoms of depression or anxiety; however, they did report more dyspnea (B = 0.31, 95% CI = 0.16 to 0.47, p < 0.001) and impairment in HRQL (B = 4.75, 95% CI = 2.10 to 7.41, p < 0.001) than other individuals with COPD. Individuals with AATD-associated COPD were more likely to be a member of a couple (rather than single) and had a higher level of education when compared to individuals with non-AATD COPD. Resources available to persons with AATD-associated COPD, such as being in a serious relationship and having higher education, may offset the effect of age when considering symptoms of depression and anxiety in patients with COPD.
Alpha-1 Antitrypsin Deficiency; Anxiety; Depression; Dyspnea; Health Status; Psychological Adjustment
We performed a genome-wide association study in non-Hispanic white subjects with fibrotic idiopathic interstitial pneumonias (N=1616) and controls (N=4683); replication was assessed in 876 cases and 1890 controls. We confirmed association with TERT and MUC5B on chromosomes 5p15 and 11p15, respectively, the chromosome 3q26 region near TERC, and identified 7 novel loci (PMeta = 2.4×10−8 to PMeta = 1.1×10−19). The novel loci include FAM13A (4q22), DSP (6p24), OBFC1 (10q24), ATP11A (13q34), DPP9 (19p13), and chromosomal regions 7q22 and 15q14-15. Our results demonstrate that genes involved in host defense, cell-cell adhesion, and DNA repair contribute to the risk of fibrotic IIP.
The value of quantitative computed tomography (QCT) to identify chronic obstructive pulmonary disease (COPD) phenotypes is increasingly appreciated. We hypothesized that QCT-defined emphysema and airway abnormalities relate to St. George's Respiratory Questionnaire (SGRQ) and BODE.
1,200 COPDGene subjects meeting GOLD criteria for COPD with QCT analysis were included. Total lung emphysema was measured using density mask technique with a -950 HU threshold. An automated program measured mean wall thickness (WT), wall area percent (WA%) and pi10 in six segmental bronchi. Separate multivariate analyses examined the relative influence of airway measures and emphysema on SGRQ and BODE.
In separate models predicting SGRQ score, a one unit standard deviation (SD) increase in each airway measure predicted higher SGRQ scores (for WT, 1.90 points higher, p=0.002; for WA%, 1.52 points higher, p=0.02; for pi10, 2.83 points higher p<0.001). The comparable increase in SGRQ for a one unit SD increase in percent emphysema in these models was relatively weaker, significant only in the pi10 model (for percent emphysema, 1.45 points higher, p=0.01). In separate models predicting BODE, a one unit SD increase in each airway measure predicted higher BODE scores (for WT, 1.07 fold increase, p<0.001; for WA%, 1.20 fold increase, p<0.001; for pi10, 1.16 fold increase, p<0.001). In these models, emphysema more strongly influenced BODE (range 1.24-1.26 fold increase, p<0.001).
Emphysema and airway disease both relate to clinically important parameters. The relative influence of airway disease is greater for SGRQ; the relative influence of emphysema is greater for BODE.
Imaging; COPD; emphysema
It can be challenging to maintain longitudinal follow-up of subjects in clinical studies. COPDGene is a multicenter, observational study designed to identify genetic factors associated with COPD and to characterize COPD-related phenotypes. To obtain follow-up data on patient's vital status and outcomes, the COPDGene Longitudinal Follow-up (LFU) Program was developed to supplement its parent study.
We used a telecommunication system that employed automated telephone contact or web-based questions to obtain longitudinal follow-up data in our subjects. A branching questionnaire asked about exacerbations, new therapies, smoking status, development of co-morbid conditions, and general health status. Study coordinators contacted subjects who did not respond to one of the automated methods. We enrolled 10,383 subjects in the COPDGene study. As of August 29, 2011, 7,959 subjects completed 19,955 surveys. On the first survey, 68.8% of subjects who completed their survey did so by electronic means, while 31.3% required coordinator phone follow-up. On each subsequent survey the number of subjects who completed their survey by electronic means increased, while the number of subjects who required coordinator follow-up decreased. Despite many of the patients in the cohort being chronically ill and elderly, there was broad acceptance of the system with over half the cohort using electronic response methods.
The COPDGene LFU Study demonstrated that telecommunications was an effective way to obtain longitudinal follow-up of subjects in a large multicenter study. Web-based and automated phone contacts are accepted by research subjects and could serve as a model for LFU in future studies.
COPD; COPDGene; Emphysema; Longitudinal data collection; Exacerbations; Follow-up studies; Elderly
Exacerbations of chronic obstructive pulmonary disease (COPD) are associated with accelerated loss of lung function and death. Identification of patients at risk for these events, particularly those requiring hospitalization, is of major importance. Severe pulmonary hypertension is an important complication of advanced COPD and predicts acute exacerbations, though pulmonary vascular abnormalities also occur early in the course of the disease. We hypothesized that a computed tomographic (CT) metric of pulmonary vascular disease (pulmonary artery enlargement, as determined by a ratio of the diameter of the pulmonary artery to the diameter of the aorta [PA:A ratio] of >1) would be associated with severe COPD exacerbations.
We conducted a multicenter, observational trial that enrolled current and former smokers with COPD. We determined the association between a PA:A ratio of more than 1 and a history at enrollment of severe exacerbations requiring hospitalization and then examined the usefulness of the ratio as a predictor of these events in a longitudinal follow-up of this cohort, as well as in an external validation cohort. We used logistic-regression and zero-inflated negative binomial regression analyses and adjusted for known risk factors for exacerbation.
Multivariate logistic-regression analysis showed a significant association between a PA:A ratio of more than 1 and a history of severe exacerbations at the time of enrollment in the trial (odds ratio, 4.78; 95% confidence interval [CI], 3.43 to 6.65; P<0.001). A PA:A ratio of more than 1 was also independently associated with an increased risk of future severe exacerbations in both the trial cohort (odds ratio, 3.44; 95% CI, 2.78 to 4.25; P<0.001) and the external validation cohort (odds ratio, 2.80; 95% CI, 2.11 to 3.71; P<0.001). In both cohorts, among all the variables analyzed, a PA:A ratio of more than 1 had the strongest association with severe exacerbations.
Pulmonary artery enlargement (a PA:A ratio of >1), as detected by CT, was associated with severe exacerbations of COPD. (Funded by the National Heart, Lung, and Blood Institute; ClinicalTrials.gov numbers, NCT00608764 and NCT00292552.)
Idiopathic pulmonary fibrosis (IPF) is a devastating disease that afflicts patients with relentlessly progressive shortness of breath [Joint Statement of the American Thoracic Society and the European Respiratory Society. Idiopathic pulmonary fibrosis: diagnosis and treatment. Am J Respir Crit Care Med 2000;161:646–641]. Despite nearly 30 years of intense investigation, effective therapy for IPF remains elusive; median survival rates have stubbornly remained less than five years from the time of diagnosis [Bjoraker JA, Ryu JH, Edwin MK, Meyers J, Tazelaar H, Schroeder D, et al. Prognostic significance of histopathologic subsets in idiopathic pulmonary fibrosis. Am J Respir Crit Care Med 1998;157:199–2032, Flaherty KR, Thwaite E, Kazerooni EA, Gross B, Toews GB, Colby TV, et al. Radiological versus histological diagnosis in UIP and NSIP: survival implications. Thorax 2003;58:143–483], and no medical therapy has been proved to be in any way effective for the treatment of this disease. Without medications that help IPF patients live longer, an important question to ask is whether there are interventions that might allow these people to live better—to be more active; to experience less dyspnea, less depression, less anxiety; to possess a greater sense of control over their disease; and to have better quality of life. Pulmonary rehabilitation helps to accomplish many of these goals in patients with chronic obstructive pulmonary disease, and emerging data suggest that it may do the same for patients with IPF.
Pulmonary fibrosis; Pulmonary rehabilitation; Dyspnea
Although prior research indicates that religious and spiritual coping is associated with positive health outcomes, few studies have examined religious and spiritual coping among patients with emphysema.
To describe the utilization of religious and spiritual coping and its relationship to quality of life among patients with emphysema, in a 2-year longitudinal follow-up study.
Forty patients with emphysema (mean age 63.5 ± 6.0 y, 8 women) who participated in the National Emphysema Treatment Trial were matched on age, sex, race, and education with 40 healthy individuals recruited from the community. We conducted baseline assessment of overall coping strategies, psychological functioning, quality of life, pulmonary function, and exercise capacity, and we assessed overall coping strategies and religious and spiritual coping at 2-year follow-up.
Ninety percent of the patients with emphysema considered themselves at least slightly religious and spiritual. The patients reported using both negative religious coping (eg, questioning God) and positive religious coping (eg, prayer) more than the healthy control subjects at follow-up. However, greater use of religious and spiritual coping was associated with poorer illness-related quality of life.
Patients with emphysema appear to use various coping strategies in responding to their illness. Future research should investigate if patients using religious and spiritual coping would benefit from interventions to address emotional distress and reduced quality of life.
emphysema; pulmonary rehabilitations; coping; depression; anxiety; quality of life; religiosity; spirituality; National Emphysema Treatment Trial
Gas trapping quantified on chest CT scans has been proposed as a surrogate for small airway disease in COPD. We sought to determine if measurements using paired inspiratory and expiratory CT scans may be better able to separate gas trapping due to emphysema from gas trapping due to small airway disease.
Smokers with and without COPD from the COPDGene Study underwent inspiratory and expiratory chest CT scans. Emphysema was quantified by the percent of lung with attenuation < −950HU on inspiratory CT. Four gas trapping measures were defined: (1) Exp−856, the percent of lung < −856HU on expiratory imaging; (2) E/I MLA, the ratio of expiratory to inspiratory mean lung attenuation; (3) RVC856-950, the difference between expiratory and inspiratory lung volumes with attenuation between −856 and −950 HU; and (4) Residuals from the regression of Exp−856 on percent emphysema.
In 8517 subjects with complete data, Exp−856 was highly correlated with emphysema. The measures based on paired inspiratory and expiratory CT scans were less strongly correlated with emphysema. Exp−856, E/I MLA and RVC856-950 were predictive of spirometry, exercise capacity and quality of life in all subjects and in subjects without emphysema. In subjects with severe emphysema, E/I MLA and RVC856-950 showed the highest correlations with clinical variables.
Quantitative measures based on paired inspiratory and expiratory chest CT scans can be used as markers of small airway disease in smokers with and without COPD, but this will require that future studies acquire both inspiratory and expiratory CT scans.
Emphysema; Chest CT scan; Small airways; Lung function tests; Smoking
The genetic risk factors for chronic obstructive pulmonary disease (COPD) are still largely unknown. To date, genome-wide association studies (GWASs) of limited size have identified several novel risk loci for COPD at CHRNA3/CHRNA5/IREB2, HHIP and FAM13A; additional loci may be identified through larger studies. We performed a GWAS using a total of 3499 cases and 1922 control subjects from four cohorts: the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE); the Normative Aging Study (NAS) and National Emphysema Treatment Trial (NETT); Bergen, Norway (GenKOLS); and the COPDGene study. Genotyping was performed on Illumina platforms with additional markers imputed using 1000 Genomes data; results were summarized using fixed-effect meta-analysis. We identified a new genome-wide significant locus on chromosome 19q13 (rs7937, OR = 0.74, P = 2.9 × 10−9). Genotyping this single nucleotide polymorphism (SNP) and another nearby SNP in linkage disequilibrium (rs2604894) in 2859 subjects from the family-based International COPD Genetics Network study (ICGN) demonstrated supportive evidence for association for COPD (P = 0.28 and 0.11 for rs7937 and rs2604894), pre-bronchodilator FEV1 (P = 0.08 and 0.04) and severe (GOLD 3&4) COPD (P = 0.09 and 0.017). This region includes RAB4B, EGLN2, MIA and CYP2A6, and has previously been identified in association with cigarette smoking behavior.
In COPD patients, hyperinflation impairs cardiac function. We examined whether lung deflation improves oxygen pulse, a surrogate marker of stroke volume.
In 129 NETT patients with cardiopulmonary exercise testing (CPET) and arterial blood gases (ABG substudy), hyperinflation was assessed with residual volume to total lung capacity ratio (RV/TLC), and cardiac function with oxygen pulse (O2 pulse=VO2/HR) at baseline and 6 months. Medical and surgical patients were divided into “deflators” and “non-deflators” based on change in RV/TLC from baseline (ΔRV/TLC). We defined deflation as the ΔRV/TLC experienced by 75% of surgical patients. We examined changes in O2 pulse at peak and similar (iso-work) exercise. Findings were validated in 718 patients who underwent CPET without ABGs.
In the ABG substudy, surgical and medical deflators improved their RV/TLC and peak O2 pulse (median ΔRV/TLC −18.0% vs. −9.3%, p=0.0003; median ΔO2 pulse 13.6% vs. 1.8%, p=0.12). Surgical deflators also improved iso-work O2 pulse (0.53 mL/beat, p=0.04 at 20 watts). In the validation cohort, surgical deflators experienced a greater improvement in peak O2 pulse than medical deflators (mean 18.9% vs. 1.1%). In surgical deflators improvements in O2 pulse at rest and during unloaded pedaling (0.32 mL/beat, p<0.0001 and 0.47 mL/beat, p<0.0001, respectively) corresponded with significant reductions in HR and improvements in VO2. On multivariate analysis, deflators were 88% more likely than non-deflators to have an improvement in O2 pulse (OR 1.88, 95% CI 1.30–2.72, p=0.0008).
In COPD, decreased hyperinflation through lung volume reduction is associated with improved O2 pulse.
cardiac function; hyperinflation; lung volume reduction surgery; oxygen pulse
Severe hypoxemia is a major complication of chronic obstructive pulmonary disease (COPD). Long term oxygen therapy is beneficial in hypoxemic COPD patients. However, the clinical and radiographic predictors of hypoxemia and the use of oxygen therapy are not well described. This study aimed to find the correlates of resting hypoxemia and the pattern of oxygen use in moderate to severe COPD patients.
Subjects with GOLD stage II or higher COPD from the first 2500 COPDGene subjects were included in this analysis. All subjects were current or ex-smokers between ages 45 and 80. Severe resting hypoxemia was defined as room air oxygen saturation (SpO2) ≤ 88%. Use of supplemental oxygen therapy was determined by questionnaire.
Eighty-two of 1060 COPD subjects (7.7%) had severe resting hypoxemia. Twenty-one of the 82 (25.6%) were not using continuous supplemental oxygen. Female sex, higher BMI, lower FEV1, and enrollment in Denver were independent risk factors for hypoxemia; emphysema severity on quantitative chest CT scan did not predict hypoxemia. 132 of 971(13.6%) subjects without severe resting hypoxemia were using continuous supplemental oxygen. In non-hypoxemic oxygen users, Denver recruitment, higher BMI, lower FEV1, and more severe dyspnea were associated with the use of continuous oxygen.
A large number of COPD patients without severe hypoxemia were using supplemental oxygen therapy and the pattern of oxygen use was affected by factors other than resting SpO2 and emphysema severity. Longitudinal data will be required to reveal the effects of oxygen therapy in this subgroup.
Hypoxemia; long-term oxygen therapy; COPD; emphysema
Cachexia, whether assessed by body mass index (BMI) or fat-free mass index (FFMI), affects a significant proportion of patients with chronic obstructive pulmonary disease (COPD), and is an independent risk factor for increased mortality, increased emphysema, and more severe airflow obstruction. The variable development of cachexia among patients with COPD suggests a role for genetic susceptibility. The objective of the present study was to determine genetic susceptibility loci involved in the development of low BMI and FFMI in subjects with COPD. A genome-wide association study (GWAS) of BMI was conducted in three independent cohorts of European descent with Global Initiative for Chronic Obstructive Lung Disease stage II or higher COPD: Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-Points (ECLIPSE; n = 1,734); Norway-Bergen cohort (n = 851); and a subset of subjects from the National Emphysema Treatment Trial (NETT; n = 365). A genome-wide association of FFMI was conducted in two of the cohorts (ECLIPSE and Norway). In the combined analyses, a significant association was found between rs8050136, located in the first intron of the fat mass and obesity–associated (FTO) gene, and BMI (P = 4.97 × 10−7) and FFMI (P = 1.19 × 10−7). We replicated the association in a fourth, independent cohort consisting of 502 subjects with COPD from COPDGene (P = 6 × 10−3). Within the largest contributing cohort of our analysis, lung function, as assessed by forced expiratory volume at 1 second, varied significantly by FTO genotype. Our analysis suggests a potential role for the FTO locus in the determination of anthropomorphic measures associated with COPD.
chronic obstructive pulmonary disease genetics; chronic obstructive pulmonary disease epidemiology; chronic obstructive pulmonary disease metabolism; genome-wide association study