Systemic Markers of Lung Function and Forced Expiratory Volume in 1 Second Decline across Diverse Cohorts.

Rationale: Chronic obstructive pulmonary disease (COPD) is a complex disease characterized by airway obstruction and accelerated lung function decline. Our understanding of systemic protein biomarkers associated with COPD remains incomplete. Objectives: To determine what proteins and pathways are associated with impaired pulmonary function in a diverse population. Methods: We studied 6,722 participants across six cohort studies with both aptamer-based proteomic and spirometry data (4,566 predominantly White participants in a discovery analysis and 2,156 African American cohort participants in a validation). In linear regression models, we examined protein associations with baseline forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity (FVC). In linear mixed effects models, we investigated the associations of baseline protein levels with rate of FEV1 decline (ml/yr) in 2,777 participants with up to 7 years of follow-up spirometry. Results: We identified 254 proteins associated with FEV1 in our discovery analyses, with 80 proteins validated in the Jackson Heart Study. Novel validated protein associations include kallistatin serine protease inhibitor, growth differentiation factor 2, and tumor necrosis factor-like weak inducer of apoptosis (discovery ß = 0.0561, Q = 4.05 × 10-10; ß = 0.0421, Q = 1.12 × 10-3; and ß = 0.0358, Q = 1.67 × 10-3, respectively). In longitudinal analyses within cohorts with follow-up spirometry, we identified 15 proteins associated with FEV1 decline (Q < 0.05), including elafin leukocyte elastase inhibitor and mucin-associated TFF2 (trefoil factor 2; ß = -4.3 ml/yr, Q = 0.049; ß = -6.1 ml/yr, Q = 0.032, respectively). Pathways and processes highlighted by our study include aberrant extracellular matrix remodeling, enhanced innate immune response, dysregulation of angiogenesis, and coagulation. Conclusions: In this study, we identify and validate novel biomarkers and pathways associated with lung function traits in a racially diverse population. In addition, we identify novel protein markers associated with FEV1 decline. Several protein findings are supported by previously reported genetic signals, highlighting the plausibility of certain biologic pathways. These novel proteins might represent markers for risk stratification, as well as novel molecular targets for treatment of COPD.

Long-term Course of Depression Trajectories in Patients With COPD: A 3-Year Follow-up Analysis of the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints Cohort.

BACKGROUND: There is insufficient evidence about the long-term course of depressive symptom trajectories and their impact among patients with COPD. METHODS: We analysed 3-year data obtained from patients with COPD participating in the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints study. Patients were split into four groups on the basis of Center for Epidemiologic Studies Depression Scale score (< 16 vs ≥ 16) and antidepressant use (yes vs no) at baseline and at 3 years: never depressed, new onset, remittent, and persistent depression. Baseline characteristics were used to assess factors associated with the group by using logistic regression. RESULTS: A total of 1,589 patients with COPD completed the 3-year follow-up. Of these, 55% (n = 869) were classified as never depressed, 24% (n = 377) were classified as persistently depressed, 14% (n = 226) developed new onset of depression, and 7% (n = 117) had depression that remitted. Female sex and history of stroke were associated with substantial increases in the odds of persistent depression (OR, 2.95; 95% CI, 2.05-4.24 and OR, 3.09; 95% CI, 1.43-6.67, respectively). Odds of new onset depression increased with worse health status (OR, 1.10; 95% CI, 1.04-1.17 per 4-point increase in St. George's Respiratory Questionnaire score) and moderate to severe dyspnea (OR, 1.57; 95% CI, 1.07-2.31 for modified Medical Research Council score ≥ 2 vs 0 or 1). During follow-up, patients with persistent or new-onset depression experienced more exacerbations and more pronounced loss in performance as assessed by reduction in the 6-min walk distance (6MWD) test score. CONCLUSIONS: About one in four patients with COPD had persistent depressive symptoms over 3 years. Clinicians should be aware of the characteristics of persistent and new onset depressive symptoms, which are associated with risk of exacerbations and loss of performance on the 6MWD test. Interventions that ameliorate the course of depression are needed. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT00292552; URL: www.clinicaltrials.gov.

Cluster analysis in the COPDGene study identifies subtypes of smokers with distinct patterns of airway disease and emphysema.

BACKGROUND: There is notable heterogeneity in the clinical presentation of patients with COPD. To characterise this heterogeneity, we sought to identify subgroups of smokers by applying cluster analysis to data from the COPDGene study. METHODS: 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. FINDINGS: We identified four clusters that can be characterised as (1) relatively resistant smokers (ie, 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 dyspnoea (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). INTERPRETATION: Cluster analysis identifies four subgroups of smokers that show robust associations with clinical characteristics of COPD and known COPD-associated genetic variants.