Individuals with chronic obstructive pulmonary disease (COPD) and asthma are an important but poorly characterised group. The genetic determinants of COPD and asthma overlap have not been studied. ...The aim of this study was to identify clinical features and genetic risk factors for COPD and asthma overlap. Subjects were current or former smoking non-Hispanic whites or African-Americans with COPD. Overlap subjects reported a history of physician-diagnosed asthma before the age of 40 years. We compared clinical and radiographic features between COPD and overlap subjects. We performed genome-wide association studies (GWAS) in the non-Hispanic whites and African-American populations, and combined these results in a meta-analysis. More females 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 non-Hispanic white GWAS identified single nucleotide polymorphisms in the genes CSMD1 (rs11779254, p=1.57 × 10(-6)) and SOX5 (rs59569785, p=1.61 × 10(-6)) and the meta-analysis identified single nucleotide polymorphisms in the gene GPR65 (rs6574978, p=1.18 × 10(-7)) associated with COPD and 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 and asthma overlap is an important syndrome and may require distinct clinical management.
Emerging data from longitudinal studies suggest that preserved ratio impaired spirometry (PRISm), defined by proportionate reductions in FEV1 and FVC, is a heterogeneous population with frequent ...transitions to other lung function categories relative to individuals with normal and obstructive spirometry. Controversy regarding the clinical significance of these transitions exists (eg, whether transitions merely reflect measurement variability or noise).
Are individuals with PRISm enriched for transitions associated with substantial changes in lung function?
Current and former smokers enrolled in the Genetic Epidemiology of COPD (COPDGene) study with spirometry available in phases 1 through 3 (enrollment, 5-year follow-up, and 10-year follow-up) were analyzed. Postbronchodilator lung function categories were as follows: PRISm (FEV1 < 80% predicted with FEV1/FVC ratio ≥ 0.7), Global Initiative for Chronic Obstructive Lung Disease grade 0 (FEV1 ≥ 80% predicted and FEV1/FVC ≥ 0.7), and obstruction (FEV1/FVC < 0.7). Significant transition status was affirmative if a subject belonged to two or more spirometric categories and had > 10% change in FEV1 % predicted and/or FVC % predicted between consecutive visits. Ever-PRISm was present if a subject had PRISm at any visit. Logistic regression examined the association between significant transitions and ever-PRISm status, adjusted for age, sex, race, FEV1 % predicted, current smoking, pack-years, BMI, and ever-positive bronchodilator response.
Among subjects with complete data (N = 1,775) over 10.1 ± 0.4 years of follow-up, the prevalence of PRISm remained consistent (10.4%-11.3%) between phases 1 through 3, but nearly one-half of subjects with PRISm transitioned into or out of PRISm at each visit. Among all subjects, 19.7% had a significant transition; ever-PRISm was a significant predictor of significant transitions (unadjusted OR, 10.3; 95% CI, 7.9-13.5; adjusted OR, 14.9; 95% CI, 10.9-20.7). Results were similar with additional adjustment for radiographic emphysema and gas trapping, when lower limit of normal criteria were used to define lung function categories, and when FEV1 alone (regardless of change in FVC % predicted) was used to define significant transitions.
PRISm is an unstable group, with frequent significant transitions to both obstruction and normal spirometry over time.
ClinicalTrials.gov; No.: NCT000608764; URL: www.clinicaltrials.gov
Diffusing capacity of the lung for carbon monoxide (Dlco) is inconsistently obtained in patients with COPD, and the added benefit of Dlco testing beyond that of more common tools is unknown.
The goal ...of this study was to determine whether lower Dlco is associated with increased COPD morbidity independent of emphysema assessed via spirometry and CT imaging.
Data for 1,806 participants with COPD from the Genetic Epidemiology of COPD (COPDGene) study 5-year visit were analyzed, including pulmonary function testing, quality of life, symptoms, exercise performance, and exacerbation rates. Dlco percent predicted was primarily analyzed as a continuous variable and additionally categorized into four groups: (1) Dlco and FEV1 > 50% (reference); (2) only Dlco ≤ 50%; (3) only FEV1 ≤ 50%; and (4) both ≤ 50% predicted. Outcomes were modeled by using multivariable linear and negative binomial regression, including emphysema and FEV1 percent predicted among other confounders.
In multivariable analyses, every 10% predicted decrease in Dlco was associated with symptoms and quality of life (COPD Assessment Test, 0.53 P < .001; St. George’s Respiratory Questionnaire, 1.67 P < .001; Medical Outcomes Study Short Form 36 Physical Function, –0.89 P < .001), exercise performance (6-min walk distance, –45.35 feet; P < .001), and severe exacerbation rate (rate ratio, 1.14; P < .001). When categorized, severe impairment in Dlco alone, FEV1 alone, or both Dlco and FEV1 were associated with significantly worse morbidity compared with the reference group (P < .05 for all outcomes).
Impairment in Dlco was associated with increased COPD symptoms, reduced exercise performance, and severe exacerbation risk even after accounting for spirometry and CT evidence of emphysema. These findings suggest that Dlco should be considered for inclusion in future multidimensional tools assessing COPD.
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.
We analysed cross-sectional data from a large multicentre cohort (COPDGene) of current and former smokers. Primary outcome was airflow obstruction (FEV
/FVC); secondary outcomes included five additional measures of disease: FEV
, 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.
10 187 subjects were included. For FEV
/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 FEV
/FVC with increase in pack-years (regression coefficient β=-0.023±SE0.003; P=0.003) and duration over all ranges of smoking cigarettes/day (β=-0.041±0.004; P<0.001) but a relatively flat slope for cigarettes/day across all ranges of smoking duration (β=-0.009±0.0.009; P=0.34). Strength of association of duration was similarly greater than pack-years for emphysema, gas trapping, FEV
, 6MWD and SGRQ.
Smoking duration alone provides stronger risk estimates of COPD than the composite index of pack-years.
Post-results; NCT00608764.
In this study, the investigators found a strong association, in two cohorts, between future exacerbations of COPD and the ratio of the diameter of the pulmonary artery to the diameter of the aorta ...(with both diameters measured from a baseline CT scan) that is greater than 1.
Acute exacerbations of chronic obstructive pulmonary disease (COPD) are critical events in the natural history of the disease and are associated with accelerated loss of lung function and poor quality of life.
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Hospitalizations for exacerbations account for $18 billion in direct costs annually in the United States and are associated with 1-year mortality of 21% and 5-year mortality of 55%.
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Identification of patients at risk for these events is therefore of major importance.
Acute exacerbations of COPD are defined as an increase in dyspnea, cough, or sputum production warranting a change in therapy. These acute exacerbations often result from . . .
To test the hypothesis-given the increasing emphasis on quantitative computed tomographic (CT) phenotypes of chronic obstructive pulmonary disease (COPD)-that a relationship exists between COPD ...exacerbation frequency and quantitative CT measures of emphysema and airway disease.
This research protocol was approved by the institutional review board of each participating institution, and all participants provided written informed consent. One thousand two subjects who were enrolled in the COPDGene Study and met the GOLD (Global Initiative for Chronic Obstructive Lung Disease) criteria for COPD with quantitative CT analysis were included. Total lung emphysema percentage was measured by using the attenuation mask technique with a -950-HU threshold. An automated program measured the mean wall thickness and mean wall area percentage in six segmental bronchi. The frequency of COPD exacerbation in the prior year was determined by using a questionnaire. Statistical analysis was performed to examine the relationship of exacerbation frequency with lung function and quantitative CT measurements.
In a multivariate analysis adjusted for lung function, bronchial wall thickness and total lung emphysema percentage were associated with COPD exacerbation frequency. Each 1-mm increase in bronchial wall thickness was associated with a 1.84-fold increase in annual exacerbation rate (P = .004). For patients with 35% or greater total emphysema, each 5% increase in emphysema was associated with a 1.18-fold increase in this rate (P = .047).
Greater lung emphysema and airway wall thickness were associated with COPD exacerbations, independent of the severity of airflow obstruction. Quantitative CT can help identify subgroups of patients with COPD who experience exacerbations for targeted research and therapy development for individual phenotypes.
The 2011 GOLD (Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease COPD) consensus report uses symptoms, exacerbation history, and forced expiratory ...volume (FEV1)% to categorise patients according to disease severity and guide treatment. We aimed to assess both the influence of symptom instrument choice on patient category assignment and prospective exacerbation risk by category.
Patients were recruited from 21 centres in the USA, as part of the COPDGene study. Eligible patients were aged 45-80 years, had smoked for 10 pack-years or more, and had an FEV1/forced vital capacity (FVC) <0·7. Categories were defined with the modified Medical Research Council (mMRC) dyspnoea scale (score 0-1 vs ≥2) and the St George's Respiratory Questionnaire (SGRQ; ≥25 vs <25 as a surrogate for the COPD Assessment Test CAT ≥10 vs <10) in addition to COPD exacerbations in the previous year (<2 vs ≥ 2), and lung function (FEV1% predicted ≥50 vs <50). Statistical comparisons were done with k-sample permutation tests. This study cohort is registered with ClinicalTrials.gov, number NCT00608764.
4484 patients with COPD were included in this analysis. Category assignment using the mMRC scale versus SGRQ were similar but not identical. On the basis of the mMRC scale, 1507 (33·6%) patients were assigned to category A, 919 (20·5%) to category B, 355 (7·9%) to category C, and 1703 (38·0%) to category D; on the basis of the SGRQ, 1317 (29·4%) patients were assigned to category A, 1109 (24·7%) to category B, 221 (4·9%) to category C, and 1837 (41·0%) to category D (κ coefficient for agreement, 0·77). Significant heterogeneity in prospective exacerbation rates (exacerbations/person-years) were seen, especially in the D subcategories, depending on the risk factor that determined category assignment (lung function only 0·89, 95% CI 0·78-1·00), previous exacerbation history only 1·34, 1·0-1·6, or both 1·86, 1·6-2·1; p<0·0001).
The GOLD classification emphasises the importance of symptoms and exacerbation risk when assessing COPD severity. The choice of symptom measure influences category assignment. The relative number of patients with low symptoms and high risk for exacerbations (category C) is low. Differences in exacerbation rates for patients in the highest risk category D were seen depending on whether risk was based on lung function, exacerbation history, or both.
National Heart, Lung, and Blood Institute, and the COPD Foundation through contributions from AstraZeneca, Boehringer Ingelheim, Novartis, and Sepracor.
Acute exacerbations of chronic obstructive pulmonary disease (COPD) increase the risk of death and drive healthcare costs, but whether they accelerate loss of lung function remains controversial. ...Whether exacerbations in subjects with mild COPD or similar acute respiratory events in smokers without airflow obstruction affect lung function decline is unknown.
To determine the association between acute exacerbations of COPD (and acute respiratory events in smokers without COPD) and the change in lung function over 5 years of follow-up.
We examined data on the first 2,000 subjects who returned for a second COPDGene visit 5 years after enrollment. Baseline data included demographics, smoking history, and computed tomography emphysema. We defined exacerbations (and acute respiratory events in those without established COPD) as acute respiratory symptoms requiring either antibiotics or systemic steroids, and severe events by the need for hospitalization. Throughout the 5-year follow-up period, we collected self-reported acute respiratory event data at 6-month intervals. We used linear mixed models to fit FEV
decline based on reported exacerbations or acute respiratory events.
In subjects with COPD, exacerbations were associated with excess FEV
decline, with the greatest effect in Global Initiative for Chronic Obstructive Lung Disease stage 1, where each exacerbation was associated with an additional 23 ml/yr decline (95% confidence interval, 2-44; P = 0.03), and each severe exacerbation with an additional 87 ml/yr decline (95% confidence interval, 23-151; P = 0.008); statistically significant but smaller effects were observed in Global Initiative for Chronic Obstructive Lung Disease stage 2 and 3 subjects. In subjects without airflow obstruction, acute respiratory events were not associated with additional FEV
decline.
Exacerbations are associated with accelerated lung function loss in subjects with established COPD, particularly those with mild disease. Trials are needed to test existing and novel therapies in subjects with early/mild COPD to potentially reduce the risk of progressing to more advanced lung disease. Clinical trial registered with www.clinicaltrials.gov (NCT 00608764).
Purpose To determine whether visually assessed patterns of emphysema at CT might provide a simple assessment of mortality risk among cigarette smokers. Materials and Methods Of the first 4000 ...cigarette smokers consecutively enrolled between 2007 and 2011 in this COPDGene study, 3171 had data available for both visual emphysema CT scores and survival. Each CT scan was retrospectively visually scored by two analysts using the Fleischner Society classification system. Severity of emphysema was also evaluated quantitatively by using percentage lung volume occupied by low-attenuation areas (voxels with attenuation of -950 HU or less) (LAA-950). Median duration of follow-up was 7.4 years. Regression analysis for the relationship between imaging patterns and survival was based on the Cox proportional hazards model, with adjustment for age, race, sex, height, weight, pack-years of cigarette smoking, current smoking status, educational level, LAA-950, and (in a second model) forced expiratory volume in 1 second (FEV
). Results Observer agreement in visual scoring was good (weighted κ values, 0.71-0.80). There were 519 deaths in the study cohort. Compared with subjects who did not have visible emphysema, mortality was greater in those with any grade of emphysema beyond trace (adjusted hazard ratios, 1.7, 2.5, 5.0, and 4.1, respectively, for mild centrilobular emphysema, moderate centrilobular emphysema, confluent emphysema, and advanced destructive emphysema, P < .001). This increased mortality generally persisted after adjusting for LAA-950. Conclusion The visual presence and severity of emphysema is associated with significantly increased mortality risk, independent of the quantitative severity of emphysema. Online supplemental material is available for this article.
Multiple studies have identified COPD subtypes by using visual or quantitative evaluation of CT images. However, there has been no systematic assessment of a combined visual and quantitative CT ...imaging classification. We integrated visually defined patterns of emphysema with quantitative imaging features and spirometry data to produce a set of 10 nonoverlapping CT imaging subtypes, and we assessed differences between subtypes in demographic features, physiological characteristics, longitudinal disease progression, and mortality.
We evaluated 9,080 current and former smokers in the COPDGene study who had available volumetric inspiratory and expiratory CT images obtained using a standardized imaging protocol. We defined 10 discrete, nonoverlapping CT imaging subtypes: no CT imaging abnormality, paraseptal emphysema (PSE), bronchial disease, small airway disease, mild emphysema, upper lobe predominant centrilobular emphysema (CLE), lower lobe predominant CLE, diffuse CLE, visual without quantitative emphysema, and quantitative without visual emphysema. Baseline and 5-year longitudinal characteristics and mortality were compared across these CT imaging subtypes.
The overall mortality differed significantly between groups (P < .01) and was highest in the 3 moderate to severe CLE groups. Subjects having quantitative but not visual emphysema and subjects with visual but not quantitative emphysema were unique groups with mild COPD, at risk for progression, and with likely different underlying mechanisms. Subjects with PSE and/or moderate to severe CLE had substantial progression of emphysema over 5 years compared with findings in subjects with no CT imaging abnormality (P < .01).
The combination of visual and quantitative CT imaging features reflects different underlying pathological processes in the heterogeneous COPD syndrome and provides a useful approach to reclassify types of COPD.
ClinicalTrials.gov; No.: NCT00608764; URL: www.clinicaltrials.gov;
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