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1.  Implications of the GOLD 2011 Disease Severity Classification in the COPDGene Cohort 
Background
The 2011 Global Strategy for the Diagnosis, Management, and Prevention of COPD (GOLD) consensus report uses symptoms, exacerbation history and FEV1% to define four categories: A, low symptoms/low risk; B, high symptoms/low risk; C, low symptoms/high risk; and D, high symptoms/high risk where risk refers to exacerbations, hospitalization and death. Our objective was to determine (1) the influence of symptom instrument on category membership and (2) prospective exacerbation risk by category.
Methods
4,484 COPD subjects from COPDGene were analyzed. All subjects had smoking history ≥ 10 pack-years and FEV1/FVC<0·7. Categories were defined using the modified Medical Research Council Dyspnea [mMRC] (0–1 versus ≥ 2) and the Saint George’s Respiratory Questionnaire [SGRQ] (≥25 versus <25 as a surrogate for the COPD Assessment Test ≥ 10 versus <10) in addition to COPD exacerbations in the prior year (<2 versus ≥ 2), and FEV1% predicted (≥50 versus <50).
Findings
Category assignment using mMRC versus SGRQ were similar but not identical. Using the mMRC, category assignments were 34% A, 21% B, 8% C and 38% D and for SGRQ were 29% A, 25% B, 5% C and 41% D (kappa=0·77). Significant heterogeneity in exacerbation rates (exacerbations/person-year) were seen particularly within the D group, depending on the risk factor that determined category assignment (lung function (0·89), prior exacerbation history (1·34) or both (1·86), p<0·001.
Interpretations
The GOLD classification emphasizes the importance of symptoms and exacerbation risk in assessing COPD severity. The choice of symptom measure influences category assignment. The relative number of subjects with low symptoms and high risk for exacerbations (category C) is low. Differences in exacerbation rates for subjects in the highest risk category D were seen depending on whether risk was based on lung function, exacerbation history or both.
doi:10.1016/S2213-2600(12)70044-9
PMCID: PMC4105297  PMID: 24321803
2.  Prospective Association Between Inflammatory Markers and Progression of Coronary Artery Calcification in Adults With and Without Type 1 Diabetes 
Diabetes Care  2013;36(7):1967-1973.
OBJECTIVE
The role of inflammation in the increased risk of cardiovascular disease in type 1 diabetes is unclear. We examined the association of inflammation and progression of coronary artery calcification (CAC)—a marker of subclinical atherosclerosis—in adults with and without type 1 diabetes.
RESEARCH DESIGN AND METHODS
A nested case-control study was performed within the prospective cohort of the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study. Participants underwent two CAC measurements ∼2.5 years apart. Case subjects (n = 204) were those with significant progression of CAC. Control subjects (n = 258) were frequency-matched to case subjects on diabetes status, sex, age, and baseline CAC status. Inflammatory marker assessments were performed on stored blood samples from baseline. A principal components analysis (PCA) was performed and a composite score derived from that analysis. The composite score was constructed by assigning a value of 1 for each PCA component where at least one of the markers exceeded the 75th percentile (range 0–4). Conditional logistic regression was used for the matching strategy.
RESULTS
The first two components of the PCA were modestly (odds ratio 1.38 [95% CI 1.08–1.77] and 1.27 [1.02–1.59], respectively) associated with CAC progression after adjustment for other risk factors. The composite score was more strongly associated with CAC progression for those with elevated markers in three or four of the principal components compared with those with none.
CONCLUSIONS
Measures of inflammation were associated with progression of CAC in a population of adults with and without type 1 diabetes.
doi:10.2337/dc12-1874
PMCID: PMC3687315  PMID: 23340891
3.  Dissecting direct and indirect genetic effects on chronic obstructive pulmonary disease (COPD) susceptibility 
Human genetics  2013;132(4):431-441.
Cigarette smoking is the major environmental risk factor for chronic obstructive pulmonary disease (COPD). Genome-wide association studies have provided compelling associations for three loci with COPD. In this study, we aimed to estimate direct, i.e., independent from smoking, and indirect effects of those loci on COPD development using mediation analysis. We included a total of 3,424 COPD cases and 1,872 unaffected controls with data on two smoking-related phenotypes: lifetime average smoking intensity and cumulative exposure to tobacco smoke (pack years). Our analysis revealed that effects of two linked variants (rs1051730 and rs8034191) in the AGPHD1/CHRNA3 cluster on COPD development are significantly, yet not entirely, mediated by the smoking-related phenotypes. Approximately 30 % of the total effect of variants in the AGPHD1/CHRNA3 cluster on COPD development was mediated by pack years. Simultaneous analysis of modestly (r2 = 0.21) linked markers in CHRNA3 and IREB2 revealed that an even larger (~42 %) proportion of the total effect of the CHRNA3 locus on COPD was mediated by pack years after adjustment for an IREB2 single nucleotide polymorphism. This study confirms the existence of direct effects of the AGPHD1/CHRNA3, IREB2, FAM13A and HHIP loci on COPD development. While the association of the AGPHD1/CHRNA3 locus with COPD is significantly mediated by smoking-related phenotypes, IREB2 appears to affect COPD independently of smoking.
doi:10.1007/s00439-012-1262-3
PMCID: PMC3600068  PMID: 23299987
4.  Effects of Mineralocorticoid Receptor Antagonists on the Risk of Sudden Cardiac Death in Patients With Left Ventricular Systolic Dysfunction 
Circulation. Heart failure  2013;6(2):166-173.
Background
Sudden cardiac death (SCD) is an important cause of death in patients with left ventricular systolic dysfunction. Mineralocorticoid receptor antagonists (MRAs) may attenuate this risk. The objective of this meta-analysis was to assess the impact of MRAs on SCD in patients with left ventricular systolic dysfunction.
Methods and Results
We systematically searched PubMed, EMBASE, Cochrane, and other databases through March 30, 2012, without language restrictions. We included trials that enrolled patients with left ventricular ejection fraction of ≤45%, randomized subjects to MRAs versus control and reported outcomes on SCD, total and cardiovascular mortality. Eight published trials that enrolled 11875 patients met inclusion criteria. Of these, 6 reported data on SCD and cardiovascular mortality, and 7 reported data on total mortality. No heterogeneity was observed among the trials. Patients treated with MRAs had 23% lower odds of experiencing SCD compared with controls (odds ratio, 0.77; 95% confidence interval, 0.66–0.89; P=0.001). Similar reductions were observed in cardiovascular (0.75; 95% confidence interval, 0.68– 0.84; P<0.001) and total mortality (odds ratio, 0.74; 95% confidence interval, 0.63–0.86; P<0.001). Although publication bias was observed, the results did not change after a trim and fill test, suggesting that the impact of this bias was likely insignificant.
Conclusions
MRAs reduce the risk of SCD in patients with left ventricular systolic dysfunction. Comparative effectiveness studies of MRAs on SCD in usual care as well as studies evaluating the efficacy of other therapies to prevent SCD in patients receiving optimal MRA therapy are needed to guide clinical decision-making.
doi:10.1161/CIRCHEARTFAILURE.112.000003
PMCID: PMC3893922  PMID: 23403436
left ventricular systolic dysfunction; meta-analysis; mineralocorticoid receptor antagonists; sudden cardiac death
5.  The effect of excess weight gain with intensive diabetes treatment on cardiovascular disease risk factors and atherosclerosis in type 1 diabetes: Results from the Diabetes Control and Complications Trial / Epidemiology of Diabetes Interventions and Complications Study (DCCT/EDIC) study 
Circulation  2012;127(2):10.1161/CIRCULATIONAHA.111.077487.
Rationale
Intensive diabetes therapy of type 1 diabetes (T1DM) reduces diabetes complications but can be associated with excess weight gain, central obesity, and dyslipidemia.
Objective
The purpose of this study was to determine if excessive weight gain with diabetes therapy of T1DM is prospectively associated with atherosclerotic disease.
Methods and Results
Subjects with T1DM (97% Caucasian, 45% female, mean age 35 years) randomly assigned to intensive (INT) or conventional (CONV) diabetes treatment during the Diabetes Control and Complications Trial (DCCT) underwent intima-media thickness (IMT) (n=1015) and coronary artery calcium (CAC) score (n=925) measurements during follow-up in the Epidemiology of Diabetes Interventions and Complications (EDIC) Study. INT subjects were classified by quartile of BMI change during the DCCT. Excess gainers (4th quartile, including CONV subjects meeting this threshold) maintained greater BMI and waist circumference (WC), needed more insulin, had greater IMT (+5%, P<0.001 EDIC year 1, P=0.003 EDIC year 6), and trended towards greater CAC scores (OR 1.55, CI 0.97 – 2.49, P=0.07) than minimal gainers. DCCT subjects meeting metabolic syndrome criteria for WC and blood pressure had greater IMT in both EDIC years (P =0.02 to <0.001); those meeting HDL criteria had greater CAC scores (OR 1.6 and CI 1.1 – 2.4, P=0.01) during follow-up. Increasing frequency of a family history of diabetes, hypertension, and hyperlipidemia was associated with greater IMT thickness with INT but not CONV.
Conclusions
Excess weight gain in DCCT is associated with sustained increases in central obesity, insulin resistance, dyslipidemia and blood pressure, as well as more extensive atherosclerosis during EDIC.
doi:10.1161/CIRCULATIONAHA.111.077487
PMCID: PMC3819101  PMID: 23212717
diabetes mellitus; carotid intima media thickness; coronary artery calcium; imaging; obesity
6.  Gender Differences of Airway Dimensions in Anatomically Matched Sites on CT in Smokers 
COPD  2011;8(4):285-292.
Rationale and Objectives
There are limited data on, and controversies regarding gender differences in the airway dimensions of smokers. Multi-detector CT (MDCT) images were analyzed to examine whether gender could explain differences in airway dimensions of anatomically matched airways in smokers.
Materials and Methods
We used VIDA imaging software to analyze MDCT scans from 2047 smokers (M:F, 1021:1026) from the COPDGene® cohort. The airway dimensions were analyzed from segmental to subsubsegmental bronchi. We compared the differences of luminal area, inner diameter, wall thickness, wall area percentage (WA%) for each airway between men and women, and multiple linear regression including covariates (age, gender, body sizes, and other relevant confounding factors) was used to determine the predictors of each airway dimensions.
Results
Lumen area, internal diameter and wall thickness were smaller for women than men in all measured airway (18.4 vs 22.5 mm2 for segmental bronchial lumen area, 10.4 vs 12.5 mm2 for subsegmental bronchi, 6.5 vs 7.7 mm2 for subsubsegmental bronchi, respectively p < 0.001). However, women had greater WA% in subsegmental and subsubsegmental bronchi. In multivariate regression, gender remained one of the most significant predictors of WA%, lumen area, inner diameter and wall thickness.
Conclusion
Women smokers have higher WA%, but lower luminal area, internal diameter and airway thickness in anatomically matched airways as measured by CT scan than do male smokers. This difference may explain, in part, gender differences in the prevalence of COPD and airflow limitation.
doi:10.3109/15412555.2011.586658
PMCID: PMC3703311  PMID: 21756032
Airway dimensions; CT scan; Gender differences; Smoker
7.  Pulmonary Arterial Enlargement and Acute Exacerbations of COPD 
The New England journal of medicine  2012;367(10):913-921.
BACKGROUND
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.
METHODS
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.
RESULTS
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.
CONCLUSIONS
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.)
doi:10.1056/NEJMoa1203830
PMCID: PMC3690810  PMID: 22938715
8.  A Multiethnic Replication Study of Plasma Lipoprotein Levels-Associated SNPs Identified in Recent GWAS 
PLoS ONE  2013;8(5):e63469.
Genome-wide association studies (GWAS) have identified a number of loci/SNPs associated with plasma total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG) levels. The purpose of this study was to replicate 40 recent GWAS-identified HDL-C-related new loci in 3 epidemiological samples comprising U.S. non-Hispanic Whites (NHWs), U.S. Hispanics, and African Blacks. In each sample, the association analyses were performed with all 4 major lipid traits regardless of previously reported specific associations with selected SNPs. A total of 22 SNPs showed nominally significant association (p<0.05) with at least one lipid trait in at least one ethnic group, although not always with the same lipid traits reported as genome-wide significant in the original GWAS. The total number of significant loci was 10 for TC, 12 for LDL-C, 10 for HDL-C, and 6 for TG levels. Ten SNPs were significantly associated with more than one lipid trait in at least one ethnic group. Six SNPs were significantly associated with at least one lipid trait in more than one ethnic group, although not always with the same trait across various ethnic groups. For 25 SNPs, the associations were replicated with the same genome-wide significant lipid traits in the same direction in at least one ethnic group; at nominal significance for 13 SNPs and with a trend for association for 12 SNPs. However, the associations were not consistently present in all ethnic groups. This observation was consistent with mixed results obtained in other studies that also examined various ethnic groups.
doi:10.1371/journal.pone.0063469
PMCID: PMC3661596  PMID: 23717430
9.  Paired inspiratory-expiratory chest CT scans to assess for small airways disease in COPD 
Respiratory Research  2013;14(1):42.
Background
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.
Methods
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.
Results
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.
Conclusions
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.
doi:10.1186/1465-9921-14-42
PMCID: PMC3627637  PMID: 23566024
Emphysema; Chest CT scan; Small airways; Lung function tests; Smoking
10.  A genome-wide association study of COPD identifies a susceptibility locus on chromosome 19q13 
Human Molecular Genetics  2011;21(4):947-957.
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.
doi:10.1093/hmg/ddr524
PMCID: PMC3298111  PMID: 22080838
11.  Lipoprotein-Associated Phospholipase A2 Activity Predicts Progression of Subclinical Coronary Atherosclerosis 
Abstract
Background
Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a lipoprotein-associated enzyme that cleaves oxidized phosphatidylcholines, generating pro-atherosclerotic lysophosphatidylcholine and oxidized free fatty acids. Lp-PLA2 is independently associated with cardiovascular disease (CVD) in a variety of populations. Coronary calcium is a measure of subclinical CVD, and progression of coronary calcification predicts future CVD events. In type 1 diabetes there is an increase in coronary calcium and CVD despite a favorable lipid profile. Levels of Lp-PLA2 in type 1 diabetes are not known, nor is the relationship between Lp-PLA2 and progression of coronary calcification.
Methods
The Coronary Artery Calcification in Type 1 Diabetes study measured coronary calcium by electron-beam computed tomography twice over a 2.6 ± 0.3-year interval. Lp-PLA2 mass and activity were measured at baseline (n = 1,097 subjects, 506 with and 591 without type 1 diabetes).
Results
In type 1 diabetes Lp-PLA2 mass was marginally higher (285 ± 79 vs. 278 ± 78 ng/mL, P = 0.1), and Lp-PLA2 activity was significantly lower (137 ± 30 vs. 146 ± 36 nmol/min/mL, P < 0.0001) than in those without diabetes. There was a greater proportion of those with progression of coronary calcification in type 1 diabetes compared with those without diabetes (24% vs. 10%, P < 0.0001). Lp-PLA2 activity was independently associated with progression of coronary calcification in multivariate analysis (4th quartile verses bottom three quartiles, odds ratio = 1.77 [1.08–2.91], P = 0.02). LpPLA2 mass was not significantly associated with progression of coronary calcification in this cohort (P = 0.09).
Conclusions
Lp-PLA2 activity predicts progression of subclinical atherosclerosis in individuals with and without type 1 diabetes.
doi:10.1089/dia.2010.0175
PMCID: PMC3101921  PMID: 21291330
12.  The Association of Genome-Wide Significant Spirometric Loci with Chronic Obstructive Pulmonary Disease Susceptibility 
Two recent metaanalyses of genome-wide association studies conducted by the CHARGE and SpiroMeta consortia identified novel loci yielding evidence of association at or near genome-wide significance (GWS) with FEV1 and FEV1/FVC. We hypothesized that a subset of these markers would also be associated with chronic obstructive pulmonary disease (COPD) susceptibility. Thirty-two single-nucleotide polymorphisms (SNPs) in or near 17 genes in 11 previously identified GWS spirometric genomic regions were tested for association with COPD status in four COPD case-control study samples (NETT/NAS, the Norway case-control study, ECLIPSE, and the first 1,000 subjects in COPDGene; total sample size, 3,456 cases and 1,906 controls). In addition to testing the 32 spirometric GWS SNPs, we tested a dense panel of imputed HapMap2 SNP markers from the 17 genes located near the 32 GWS SNPs and in a set of 21 well studied COPD candidate genes. Of the previously identified GWS spirometric genomic regions, three loci harbored SNPs associated with COPD susceptibility at a 5% false discovery rate: the 4q24 locus including FLJ20184/INTS12/GSTCD/NPNT, the 6p21 locus including AGER and PPT2, and the 5q33 locus including ADAM19. In conclusion, markers previously associated at or near GWS with spirometric measures were tested for association with COPD status in data from four COPD case-control studies, and three loci showed evidence of association with COPD susceptibility at a 5% false discovery rate.
doi:10.1165/rcmb.2011-0055OC
PMCID: PMC3262664  PMID: 21659657
13.  Genome-wide association study of smoking behaviors in COPD patients 
Thorax  2011;66(10):894-902.
Background
Cigarette smoking is a major risk factor for COPD and COPD severity. Previous genome-wide association studies (GWAS) have identified numerous single nucleotide polymorphisms (SNPs) associated with the number of cigarettes smoked per day (CPD) and a Dopamine Beta-Hydroxylase (DBH) locus associated with smoking cessation in multiple populations.
Objective
To identify SNPs associated with lifetime average and current CPD, age at smoking initiation, and smoking cessation in COPD subjects.
Methods
GWAS were conducted in 4 independent cohorts encompassing 3,441 ever-smoking COPD subjects (GOLD stage II or higher). Untyped SNPs were imputed using HapMap (phase II) panel. Results from all cohorts were meta-analyzed.
Results
Several SNPs near the HLA region on chromosome 6p21 and in an intergenic region on chromosome 2q21 showed associations with age at smoking initiation, both with the lowest p=2×10−7. No SNPs were associated with lifetime average CPD, current CPD or smoking cessation with p<10−6. Nominally significant associations with candidate SNPs within alpha-nicotinic acetylcholine receptors 3/5 (CHRNA3/CHRNA5; e.g. p=0.00011 for SNP rs1051730) and Cytochrome P450 2A6 (CYP2A6; e.g. p=2.78×10−5 for a nonsynonymous SNP rs1801272) regions were observed for lifetime average CPD, however only CYP2A6 showed evidence of significant association with current CPD. A candidate SNP (rs3025343) in the DBH was significantly (p=0.015) associated with smoking cessation.
Conclusion
We identified two candidate regions associated with age at smoking initiation in COPD subjects. Associations of CHRNA3/CHRNA5 and CYP2A6 loci with CPD and DBH with smoking cessation are also likely of importance in the smoking behaviors of COPD patients.
doi:10.1136/thoraxjnl-2011-200154
PMCID: PMC3302576  PMID: 21685187
Chronic Obstructive Pulmonary Disease (COPD); Genome Wide Association study (GWAS); smoking behaviors; Single Nucleotide Polymorphism (SNP)
14.  Early-Onset Chronic Obstructive Pulmonary Disease Is Associated with Female Sex, Maternal Factors, and African American Race in the COPDGene Study 
Rationale: The characterization of young adults who develop late-onset diseases may augment the detection of novel genes and promote new pathogenic insights.
Methods: We analyzed data from 2,500 individuals of African and European ancestry in the COPDGene Study. Subjects with severe, early-onset chronic obstructive pulmonary disease (COPD) (n = 70, age < 55 yr, FEV1 < 50% predicted) were compared with older subjects with COPD (n = 306, age > 64 yr, FEV1 < 50% predicted).
Measurements and Main Results: Subjects with severe, early-onset COPD were predominantly females (66%), P = 0.0004. Proportionally, early-onset COPD was seen in 42% (25 of 59) of African Americans versus 14% (45 of 317) of non-Hispanic whites, P < 0.0001. Other risk factors included current smoking (56 vs. 17%, P < 0.0001) and self-report of asthma (39 vs. 25%, P = 0.008). Maternal smoking (70 vs. 44%, P = 0.0001) and maternal COPD (23 vs. 12%, P = 0.03) were reported more commonly in subjects with early-onset COPD. Multivariable regression analysis found association with African American race, odds ratio (OR), 7.5 (95% confidence interval [CI], 2.3–24; P = 0.0007); maternal COPD, OR, 4.7 (95% CI, 1.3–17; P = 0.02); female sex, OR, 3.1 (95% CI, 1.1–8.7; P = 0.03); and each pack-year of smoking, OR, 0.98 (95% CI, 0.96–1.0; P = 0.03).
Conclusions: These observations support the hypothesis that severe, early-onset COPD is prevalent in females and is influenced by maternal factors. Future genetic studies should evaluate (1) gene-by-sex interactions to address sex-specific genetic contributions and (2) gene-by-race interactions.
doi:10.1164/rccm.201011-1928OC
PMCID: PMC3175544  PMID: 21562134
chronic obstructive pulmonary disease; female; African Americans
15.  Clinical and Radiographic Predictors of GOLD–Unclassified Smokers in the COPDGene Study 
Rationale: A significant proportion of smokers have lung function impairment characterized by a reduced FEV1 with a preserved FEV1/FVC ratio. These smokers are a poorly characterized group due to their systematic exclusion from chronic obstructive pulmonary disease (COPD) studies.
Objectives: To characterize the clinical, functional, and radiographic features of Global Initiative for Chronic Obstructive Lung Disease (GOLD)-Unclassified (FEV1/FVC ≥ 0.7 and FEV1 < 80% predicted) and lower limits of normal (LLN)-unclassified (FEV1/FVC ≥ LLN and FEV1 < LLN) subjects compared to smokers with normal lung function and subjects with COPD.
Methods: Data from the first 2,500 subjects enrolled in the COPDGene study were analyzed. All subjects had 10 or more pack-years of smoking and were between the ages of 45 and 80 years. Multivariate regression models were constructed to determine the clinical and radiological variables associated with GOLD-Unclassified (GOLD-U) and LLN-Unclassified status. Separate multivariate regressions were performed in the subgroups of subjects with complete radiologic measurement variables available.
Measurements and Main Results: GOLD-U smokers account for 9% of smokers in COPDGene and have increased body mass index (BMI), a disproportionately reduced total lung capacity, and a higher proportion of nonwhite subjects and subjects with diabetes. GOLD-U subjects exhibit increased airway wall thickness compared to smoking control subjects and decreased gas trapping and bronchodilator responsiveness compared to subjects with COPD. When LLN criteria were used to define the “unclassified” group, African American subjects were no longer overrepresented. Both GOLD-U and LLN-Unclassified subjects demonstrated a wide range of lung function impairment, BMI, and percentage of total lung emphysema.
Conclusions: Subjects with reduced FEV1 and a preserved FEV1/FVC ratio are a heterogeneous group with significant symptoms and functional limitation who likely have a variety of underlying etiologies beyond increased BMI.
Clinical trial registered with www.clinicaltrials.gov (NCT000608764).
doi:10.1164/rccm.201101-0021OC
PMCID: PMC3172890  PMID: 21493737
lung diseases, classification; lung diseases, diagnosis; lung diseases, epidemiology
16.  Gender Differences in the Prognostic Value of Exercise Treadmill Test Characteristics 
American heart journal  2011;161(5):908-914.
Background
Although exercise treadmill testing (ETT) is known to be less sensitive and specific for diagnosis of coronary disease in women, little is known about gender differences in the prognostic importance of ETT variables.
Methods
We studied9569 consecutive patients (46.8% women) referred for ETT between July 2001- June 2004 in a community-based system. We assessed the association between ETT variables (exercise capacity, symptoms, ST-segment deviations, heart rate recovery, and chronotropic response) and time to all-cause death and myocardial infarction adjusting for patient and stress test characteristics. Models were stratified by gender to determine the relationship between ETT variables and outcomes.
Results
In the entire population, exercise capacity and heart rate recovery were significantly associated with all-cause death, whereas, exercise capacity, chest pain and ST-segment deviations were significantly associated with subsequent MI. The relationship between ETT variables and outcomes were similar between men and women except for abnormal exercise capacity, which was had a significantly stronger association with death in men (men: HR = 2.89, 95% CI 1.89–4.44; women: HR = 0.99, 95% CI 0.52–1.93; interaction
Conclusions
While many traditional ETT variables had similar prognostic value in both men and women, exercise capacity was more prognostically important in men and chronotropic incompetence was more important in women. Future studies should confirm these findings in additional populations.
doi:10.1016/j.ahj.2011.01.021
PMCID: PMC3096065  PMID: 21570521
gender differences; stress testing; prognosis
OBJECTIVE
Coronary artery calcification (CAC) and thoracic aortic calcificatio (TAC) are frequently detected on ungated multi-detector computed tomography (MDCT) performed for lung evaluations. We sought to evaluate concordance of CAC and TAC scores on ungated (thoracic) and ECG-gated (cardiac) MDCT scans.
METHODS
Fifty patients, enrolled in the Genetic Epidemiology of COPD study (COPDGene), were recruited to undergo gated CAC scans using 64-detector row CT, in addition to the ungated thoracic studies already being obtained as part of their study evaluation. Coronary and thoracic calcium was measured similarly (Agatston score, requiring 3 contiguous voxels of >130 Hounsfield units) using low-dose ungated studies and ECG-gated MDCT performed at the same scanning session. Intertechnique scoring variability and concordance were calculated.
RESULTS
Correlations between gated and ungated CAC and TAC were excellent (r = 0.96). The relative differences (median variability) measured by ECG-gated vs. ungated MDCT were relatively high for CAC (44%) but not for TAC (8%). Prevalence of depicted CAC (n=33, 66%) and TAC (n=21, 42%) were coincident between ECG-gated and ungated MDCT, respectively (inter-technique concordance 100%). Bland-Altman plots for CAC demonstrated mean differences of 354 (CI 169–538) and 16.1(CI −89–121).
CONCLUSION
Low-dose ungated MDCT is reliable for prediction of the presence of CAC and assessment of Agatston score. Concordance between methods and between TAC and CAC is high. This technique should allow for atherosclerotic disease risk stratification among patients undergoing ungated lung CT evaluation without requiring additional scanning. Measurement of TAC is almost as accurate from gated CT, and CAC scores are highly concordant.
doi:10.1016/j.jcct.2010.11.002
PMCID: PMC3075464  PMID: 21167806
Diabetes Care  2011;34(2):454-458.
OBJECTIVE
The objective of this study is to examine the relationship among serum levels of 25-hydroxyvitamin D (25[OH]D), polymorphisms in vitamin D-associated genes, and the presence and progression of coronary artery calcification (CAC) in adults with type 1 diabetes.
RESEARCH DESIGN AND METHODS
This prospective study included 374 non-Hispanic white individuals with type 1 diabetes (mean age 40 ± 9 years; 46% were male). CAC was measured at the baseline and 3- and 6-year follow-up visits were determined by electron beam computed tomography. Serum 25[OH]D levels were measured by liquid chromatography tandem mass spectrometry at the 3-year visit.
RESULTS
Normal (>30 ng/mL), insufficient (20–30 ng/mL), and deficient (<20 ng/mL) 25-[OH]D levels were present in 65%, 25%, and 10% of the individuals with type 1 diabetes, respectively. 25[OH]D deficiency was associated with the presence of CAC at the 3-year visit, odds ratio (OR) = 3.3 (95% CI 1.6–7.0), adjusting for age, sex, and hours of daylight. In subjects free of CAC at the 3-year visit, 25[OH]D deficiency predicted the development of CAC over the next 3 years in those with the vitamin D receptor M1T CC genotype (OR = 6.5 [1.1–40.2], P = 0.04) than in those with the CT or TT genotype (OR = 1.6 [0.3–8.6], P = 0.57).
CONCLUSIONS
Vitamin D deficiency independently predicts prevalence and development of CAC, a marker of coronary artery plaque burden, in individuals with type 1 diabetes.
doi:10.2337/dc10-0757
PMCID: PMC3024366  PMID: 20978098
Aims:
The aim was to review epidemiologic studies to reassess whether serum levels of triglycerides should be considered independently of high-density lipoprotein-cholesterol (HDL-C) as a predictor of coronary heart disease (CHD).
Methods and results:
We systematically reviewed population-based cohort studies in which baseline serum levels of triglycerides and HDL-C were included as explanatory variables in multivariate analyses with the development of CHD (coronary events or coronary death) as dependent variable. A total of 32 unique reports describing 38 cohorts were included. The independent association between elevated triglycerides and risk of CHD was statistically significant in 16 of 30 populations without pre-existing CHD. Among populations with diabetes mellitus or pre-existing CHD, or the elderly, triglycerides were not significantly independently associated with CHD in any of 8 cohorts. Triglycerides and HDL-C were mutually exclusive predictors of coronary events in 12 of 20 analyses of patients without pre-existing CHD.
Conclusions:
Epidemiologic studies provide evidence of an association between triglycerides and the development of primary CHD independently of HDL-C. Evidence of an inverse relationship between triglycerides and HDL-C suggests that both should be considered in CHD risk estimation and as targets for intervention.
PMCID: PMC2672447  PMID: 19436658
coronary heart disease; triglycerides; high-density lipoprotein-cholesterol; low-density lipoprotein-cholesterol; hypercholesterolemia
Diabetes  2010;59(7):1771-1779.
OBJECTIVE
Individuals with type 1 diabetes have a less atherogenic fasting lipid profile than those without diabetes but paradoxically have increased rates of cardiovascular disease (CVD). We investigated differences in lipoprotein subfraction cholesterol distribution and insulin resistance between subjects with and without type 1 diabetes to better understand the etiology of increased CVD risk.
RESEARCH DESIGN AND METHODS
Fast protein liquid chromatography was used to fractionate lipoprotein cholesterol distribution in a substudy of the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study (n = 82, age 46 ± 8 years, 52% female, 49% with type 1 diabetes for 23 ± 8 years). Insulin resistance was assessed by a hyperinsulinemic-euglycemic clamp.
RESULTS
Among men, those with type 1 diabetes had less VLDL and more HDL cholesterol than control subjects (P < 0.05), but among women, those with diabetes had a shift in cholesterol to denser LDL, despite more statin use. Among control subjects, men had more cholesterol distributed as VLDL and LDL but less as HDL than women; however, among those with type 1 diabetes, there was no sex difference. Within sex and diabetes strata, a more atherogenic cholesterol distribution by insulin resistance was seen in men with and without diabetes, but only in women with type 1 diabetes.
CONCLUSIONS
The expected sex-based less atherogenic lipoprotein cholesterol distribution was not seen in women with type 1 diabetes. Moreover, insulin resistance was associated with a more atherogenic lipoprotein cholesterol distribution in all men and in women with type 1 diabetes. This lipoprotein cholesterol distribution may contribute to sex-based differences in CVD in type 1 diabetes.
doi:10.2337/db09-1626
PMCID: PMC2889778  PMID: 20393149
Objective
To assess the relationship between mortality and impairment and decline in a specific executive cognitive function, the capacity for behavioral self-regulation.
Study Design & Setting
This study examined the association between mortality and baseline and 22-month decline in the capacity for behavioral self-regulation, as measured by the Behavioral Dyscontrol Scale, among 1,293 participants of the San Luis Valley Health and Aging Study (SLVHAS), a population-based longitudinal study. The Behavioral Dyscontrol Scale and a measure of overall mental status, the Mini-Mental State Examination, were administered at baseline and follow-up interviews. Cox regression was used to examine baseline and decline in capacity for behavioral self-regulation as possible predictors of morality.
Results
Baseline Behavioral Dyscontrol Scale score was predictive of mortality, independent of demographics and comorbidity count (HR=1.07; 95% CI:1.04–1.09). It remained a significant predictor with further adjustment for Mini-Mental State Examination score. Decline in this specific executive cognitive function was associated with mortality after adjustment for covariates and baseline cognitive scores (HR=1.09; 95% CI:1.04–1.13).
Conclusion
Thus, both baseline capacity for behavioral self-regulation and its decline over time predicted mortality in the SLVHAS cohort. These associations may partly be due to maintaining the ability for self-care. Understanding how specific forms of impairment contribute to mortality may help identify patients who could benefit from early intervention.
doi:10.1016/j.jclinepi.2009.06.004
PMCID: PMC2822133  PMID: 19716261
executive cognitive function; cognitive impairment; cognitive decline; mortality; Hispanic; San Luis Valley Health and Aging Study
COPD  2010;7(1):32-43.
Background
COPDGeneis a multicenter observational study designed to identify genetic factors associated with COPD. It will also characterize chest CT phenotypes in COPD subjects, including assessment of emphysema, gas trapping, and airway wall thickening. Finally, subtypes of COPD based on these phenotypes will be used in a comprehensive genome-wide study to identify COPD susceptibility genes.
Methods/Results
COPDGene will enroll 10,000 smokers with and without COPD across the GOLD stages. Both Non-Hispanic white and African-American subjects are included in the cohort. Inspiratory and expiratory chest CT scans will be obtained on all participants. In addition to the cross-sectional enrollment process, these subjects will be followed regularly for longitudinal studies. A genome-wide association study (GWAS) will be done on an initial group of 4000 subjects to identify genetic variants associated with case-control status and several quantitative phenotypes related to COPD. The initial findings will be verified in an additional 2000 COPD cases and 2000 smoking control subjects, and further validation association studies will be carried out.
Conclusions
COPDGene will provide important new information about genetic factors in COPD, and will characterize the disease process using high resolution CT scans. Understanding genetic factors and CT phenotypes that define COPD will potentially permit earlier diagnosis of this disease and may lead to the development of treatments to modify progression.
doi:10.3109/15412550903499522
PMCID: PMC2924193  PMID: 20214461
Respiratory Research  2011;12(1):9.
Background
Cigarette smoking is the principal environmental risk factor for developing COPD, and nicotine dependence strongly influences smoking behavior. This study was performed to elucidate the relationship between nicotine dependence, genetic susceptibility to nicotine dependence, and volumetric CT findings in smokers.
Methods
Current smokers with COPD (GOLD stage ≥ 2) or normal spirometry were analyzed from the COPDGene Study, a prospective observational study. Nicotine dependence was determined by the Fagerstrom test for nicotine dependence (FTND). Volumetric CT acquisitions measuring the percent of emphysema on inspiratory CT (% of lung <-950 HU) and gas trapping on expiratory CT (% of lung <-856 HU) were obtained. Genotypes for two SNPs in the CHRNA3/5 region (rs8034191, rs1051730) previously associated with nicotine dependence and COPD were analyzed for association to COPD and nicotine dependence phenotypes.
Results
Among 842 currently smoking subjects (335 COPD cases and 507 controls), 329 subjects (39.1%) showed high nicotine dependence. Subjects with high nicotine dependence had greater cumulative and current amounts of smoking. However, emphysema severity was negatively correlated with the FTND score in controls (ρ = -0.19, p < .0001) as well as in COPD cases (ρ = -0.18, p = 0.0008). Lower FTND score, male gender, lower body mass index, and lower FEV1 were independent risk factors for emphysema severity in COPD cases. Both CHRNA3/5 SNPs were associated with FTND in current smokers. An association of genetic variants in CHRNA3/5 with severity of emphysema was only found in former smokers, but not in current smokers.
Conclusions
Nicotine dependence was a negative predictor for emphysema on CT in COPD and control smokers. Increased inflammation in more highly addicted current smokers could influence the CT lung density distribution, which may influence genetic association studies of emphysema phenotypes.
Trial registration
ClinicalTrials (NCT): NCT00608764
doi:10.1186/1465-9921-12-9
PMCID: PMC3033825  PMID: 21232152
Abstract
Background
Cystatin C has been proposed to better estimate renal function and predict cardiovascular disease (CVD) than serum creatinine. To expand on our previous report, we investigated whether the relationship of cystatin C to progression of coronary artery atherosclerosis (CA) differed between individuals with type 1 diabetes (T1D) and persons without diabetes.
Methods
Coronary artery calcium was measured twice over 2.4 ± 0.4 years (n = 1,123, age = 39 ± 9 years, 47% male, 45% T1D). Significant CA progression was defined as a ≥2.5 increase in square root calcium volume score or development of clinical coronary artery disease. Stepwise multiple logistic regression was performed to investigate whether the association of cystatin C to CA progression differed by T1D status.
Results
The main finding and novelty of this article is that while the univariate association of cystatin C to CA progression was similar in T1D patients and persons without diabetes mellitus and in the expected direction (increased cystatin C as a biomarker of worsening renal function associated with CA progression), the association of cystatin C to progression of CA differed by T1D status (P = 0.01) after adjustment for other CVD risk factors. Unexpectedly, in persons without diabetes mellitus having relatively normal renal function, increased cystatin C was associated with decreased CA progression (odd ratio [OR] = 0.65, 95% confidence interval 0.44–0.96, P = 0.029) after adjustment, primarily due to adjustment for body mass index (BMI). Removal of BMI from this model resulted in a 49% change in the OR.
Conclusions
Our hypothesis-generating data suggest a complex relationship among cystatin C, BMI, and CA progression that requires further study.
doi:10.1089/dia.2009.0086
PMCID: PMC2883530  PMID: 20082582
Biochimica et biophysica acta  2009;1791(11):1057-1065.
Our aim was to identify an insulin response element (IRE) in the lipoprotein lipase (LPL) gene. We identified a 19 bp sequence as a putative IRE in LPL non-coding exon 10 using bioinformatics. Upon sequencing the IRE region, a novel 5 bp deletion was identified in Hispanics (N=406) with a carrier frequency of 4.2% but not in non-Hispanic whites (N=604) or Africans. Electrophoretic mobility shift assay revealed binding sites for regulatory factor(s) in muscle cell nuclear extracts with putative IRE sequence. Antibody supershift assay using human aorta smooth muscle cell nuclear extract revealed that Elk-1 specifically binds to putative IRE. TaqMan real-time RT-PCR of the 5 bp deletion, the mutant and wild type cDNA expressed in COS-1 and human muscle cells revealed that the 5 bp deletion was associated with modest reduction in LPL expression. There was also a slight reduction in LPL translation in the deletion mutant. Our data suggest the presence of an IRE in the 3′UTR of the LPL gene.
doi:10.1016/j.bbalip.2009.06.003
PMCID: PMC2753688  PMID: 19563912
Lipoprotein lipase; Exon 10 mutation; Electrophoretic mobility shift assay

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