The Effects of Rare SERPINA1 Variants on Lung Function and Emphysema in SPIROMICS.

Rationale: The role of PI (protease inhibitor) type Z heterozygotes and additional rare variant genotypes in the gene encoding alpha-1 antitrypsin, SERPINA1 (serpin peptidase inhibitor, clade A, member 1), in determining chronic obstructive pulmonary disease risk and severity is controversial.Objectives: To comprehensively evaluate the effects of rare SERPINA1 variants on lung function and emphysema phenotypes in subjects with significant tobacco smoke exposure using deep gene resequencing and alpha-1 antitrypsin concentrations.Methods: DNA samples from 1,693 non-Hispanic white individuals, 385 African Americans, and 90 Hispanics with ≥20 pack-years smoking were resequenced for the identification of rare variants (allele frequency < 0.05) in 16.9 kB of SERPINA1.Measurements and Main Results: White PI Z heterozygotes confirmed by sequencing (MZ; n = 74) had lower post-bronchodilator FEV1 (P = 0.007), FEV1/FVC (P = 0.003), and greater computed tomography-based emphysema (P = 0.02) compared with 1,411 white individuals without PI Z, S, or additional rare variants denoted as VR. PI Z-containing compound heterozygotes (ZS/ZVR; n = 7) had lower FEV1/FVC (P = 0.02) and forced expiratory flow, midexpiratory phase (P = 0.009). Nineteen white heterozygotes for five non-S/Z coding variants associated with lower alpha-1 antitrypsin had greater computed tomography-based emphysema compared with those without rare variants. In African Americans, a 5' untranslated region insertion (rs568223361) was associated with lower alpha-1 antitrypsin and functional small airway disease (P = 0.007).Conclusions: In this integrative deep sequencing study of SERPINA1 with alpha-1 antitrypsin concentrations in a heavy smoker and chronic obstructive pulmonary disease cohort, we confirmed the effects of PI Z heterozygote and compound heterozygote genotypes. We demonstrate the cumulative effects of multiple SERPINA1 variants on alpha-1 antitrypsin deficiency, lung function, and emphysema, thus significantly increasing the frequency of SERPINA1 variation associated with respiratory disease in at-risk smokers.

Human airway branch variation and chronic obstructive pulmonary disease.

Susceptibility to chronic obstructive pulmonary disease (COPD) beyond cigarette smoking is incompletely understood, although several genetic variants associated with COPD are known to regulate airway branch development. We demonstrate that in vivo central airway branch variants are present in 26.5% of the general population, are unchanged over 10 y, and exhibit strong familial aggregation. The most common airway branch variant is associated with COPD in two cohorts (n = 5,054), with greater central airway bifurcation density, and with emphysema throughout the lung. The second most common airway branch variant is associated with COPD among smokers, with narrower airway lumens in all lobes, and with genetic polymorphisms within the FGF10 gene. We conclude that central airway branch variation, readily detected by computed tomography, is a biomarker of widely altered lung structure with a genetic basis and represents a COPD susceptibility factor.

Clinical Significance of Symptoms in Smokers with Preserved Pulmonary Function.

BACKGROUND: Currently, the diagnosis of chronic obstructive pulmonary disease (COPD) requires a ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) of less than 0.70 as assessed by spirometry after bronchodilator use. However, many smokers who do not meet this definition have respiratory symptoms. METHODS: We conducted an observational study involving 2736 current or former smokers and controls who had never smoked and measured their respiratory symptoms using the COPD Assessment Test (CAT; scores range from 0 to 40, with higher scores indicating greater severity of symptoms). We examined whether current or former smokers who had preserved pulmonary function as assessed by spirometry (FEV1:FVC ≥0.70 and an FVC above the lower limit of the normal range after bronchodilator use) and had symptoms (CAT score, ≥10) had a higher risk of respiratory exacerbations than current or former smokers with preserved pulmonary function who were asymptomatic (CAT score, <10) and whether those with symptoms had different findings from the asymptomatic group with respect to the 6-minute walk distance, lung function, or high-resolution computed tomographic (HRCT) scan of the chest. RESULTS: Respiratory symptoms were present in 50% of current or former smokers with preserved pulmonary function. The mean (±SD) rate of respiratory exacerbations among symptomatic current or former smokers was significantly higher than the rates among asymptomatic current or former smokers and among controls who never smoked (0.27±0.67 vs. 0.08±0.31 and 0.03±0.21 events, respectively, per year; P<0.001 for both comparisons). Symptomatic current or former smokers, regardless of history of asthma, also had greater limitation of activity, slightly lower FEV1, FVC, and inspiratory capacity, and greater airway-wall thickening without emphysema according to HRCT than did asymptomatic current or former smokers. Among symptomatic current or former smokers, 42% used bronchodilators and 23% used inhaled glucocorticoids. CONCLUSIONS: Although they do not meet the current criteria for COPD, symptomatic current or former smokers with preserved pulmonary function have exacerbations, activity limitation, and evidence of airway disease. They currently use a range of respiratory medications without any evidence base. (Funded by the National Heart, Lung, and Blood Institute and the Foundation for the National Institutes of Health; SPIROMICS ClinicalTrials.gov number, NCT01969344.).

Imaging-based clusters in former smokers of the COPD cohort associate with clinical characteristics: the SubPopulations and intermediate outcome measures in COPD study (SPIROMICS).

BACKGROUND: Quantitative computed tomographic (QCT) imaging-based metrics enable to quantify smoking induced disease alterations and to identify imaging-based clusters for current smokers. We aimed to derive clinically meaningful sub-groups of former smokers using dimensional reduction and clustering methods to develop a new way of COPD phenotyping. METHODS: An imaging-based cluster analysis was performed for 406 former smokers with a comprehensive set of imaging metrics including 75 imaging-based metrics. They consisted of structural and functional variables at 10 segmental and 5 lobar locations. The structural variables included lung shape, branching angle, airway-circularity, airway-wall-thickness, airway diameter; the functional variables included regional ventilation, emphysema percentage, functional small airway disease percentage, Jacobian (volume change), anisotropic deformation index (directional preference in volume change), and tissue fractions at inspiration and expiration. RESULTS: We derived four distinct imaging-based clusters as possible phenotypes with the sizes of 100, 80, 141, and 85, respectively. Cluster 1 subjects were asymptomatic and showed relatively normal airway structure and lung function except airway wall thickening and moderate emphysema. Cluster 2 subjects populated with obese females showed an increase of tissue fraction at inspiration, minimal emphysema, and the lowest progression rate of emphysema. Cluster 3 subjects populated with older males showed small airway narrowing and a decreased tissue fraction at expiration, both indicating air-trapping. Cluster 4 subjects populated with lean males were likely to be severe COPD subjects showing the highest progression rate of emphysema. CONCLUSIONS: QCT imaging-based metrics for former smokers allow for the derivation of statistically stable clusters associated with unique clinical characteristics. This approach helps better categorization of COPD sub-populations; suggesting possible quantitative structural and functional phenotypes.

Common Genetic Polymorphisms Influence Blood Biomarker Measurements in COPD.

Implementing precision medicine for complex diseases such as chronic obstructive lung disease (COPD) will require extensive use of biomarkers and an in-depth understanding of how genetic, epigenetic, and environmental variations contribute to phenotypic diversity and disease progression. A meta-analysis from two large cohorts of current and former smokers with and without COPD [SPIROMICS (N = 750); COPDGene (N = 590)] was used to identify single nucleotide polymorphisms (SNPs) associated with measurement of 88 blood proteins (protein quantitative trait loci; pQTLs). PQTLs consistently replicated between the two cohorts. Features of pQTLs were compared to previously reported expression QTLs (eQTLs). Inference of causal relations of pQTL genotypes, biomarker measurements, and four clinical COPD phenotypes (airflow obstruction, emphysema, exacerbation history, and chronic bronchitis) were explored using conditional independence tests. We identified 527 highly significant (p < 8 X 10-10) pQTLs in 38 (43%) of blood proteins tested. Most pQTL SNPs were novel with low overlap to eQTL SNPs. The pQTL SNPs explained >10% of measured variation in 13 protein biomarkers, with a single SNP (rs7041; p = 10-392) explaining 71%-75% of the measured variation in vitamin D binding protein (gene = GC). Some of these pQTLs [e.g., pQTLs for VDBP, sRAGE (gene = AGER), surfactant protein D (gene = SFTPD), and TNFRSF10C] have been previously associated with COPD phenotypes. Most pQTLs were local (cis), but distant (trans) pQTL SNPs in the ABO blood group locus were the top pQTL SNPs for five proteins. The inclusion of pQTL SNPs improved the clinical predictive value for the established association of sRAGE and emphysema, and the explanation of variance (R2) for emphysema improved from 0.3 to 0.4 when the pQTL SNP was included in the model along with clinical covariates. Causal modeling provided insight into specific pQTL-disease relationships for airflow obstruction and emphysema. In conclusion, given the frequency of highly significant local pQTLs, the large amount of variance potentially explained by pQTL, and the differences observed between pQTLs and eQTLs SNPs, we recommend that protein biomarker-disease association studies take into account the potential effect of common local SNPs and that pQTLs be integrated along with eQTLs to uncover disease mechanisms. Large-scale blood biomarker studies would also benefit from close attention to the ABO blood group.

Genome-wide association study of lung function and clinical implication in heavy smokers.

BACKGROUND: The aim of this study is to identify genetic loci associated with post-bronchodilator FEV1/FVC and FEV1, and develop a multi-gene predictive model for lung function in COPD. METHODS: Genome-wide association study (GWAS) of post-bronchodilator FEV1/FVC and FEV1 was performed in 1645 non-Hispanic White European descent smokers. RESULTS: A functional rare variant in SERPINA1 (rs28929474: Glu342Lys) was significantly associated with post-bronchodilator FEV1/FVC (p = 1.2 × 10- 8) and FEV1 (p = 2.1 × 10- 9). In addition, this variant was associated with COPD (OR = 2.3; p = 7.8 × 10- 4) and severity (OR = 4.1; p = 0.0036). Heterozygous subjects (CT genotype) had significantly lower lung function and higher percentage of COPD and more severe COPD than subjects with the CC genotype. 8.6% of the variance of post-bronchodilator FEV1/FVC can be explained by SNPs in 10 genes with age, sex, and pack-years of cigarette smoking (P <  2.2 × 10- 16). CONCLUSIONS: This study is the first to show genome-wide significant association of rs28929474 in SERPINA1 with lung function. Of clinical importance, heterozygotes of rs28929474 (4.7% of subjects) have significantly reduced pulmonary function, demonstrating a major impact in smokers. The multi-gene model is significantly associated with CT-based emphysema and clinical outcome measures of severity. Combining genetic information with demographic and environmental factors will further increase the predictive power for assessing reduced lung function and COPD severity.

Imaging-based clusters in current smokers of the COPD cohort associate with clinical characteristics: the SubPopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS).

BACKGROUND: Classification of COPD is usually based on the severity of airflow, which may not sensitively differentiate subpopulations. Using a multiscale imaging-based cluster analysis (MICA), we aim to identify subpopulations for current smokers with COPD. METHODS: Among the SPIROMICS subjects, we analyzed computed tomography images at total lung capacity (TLC) and residual volume (RV) of 284 current smokers. Functional variables were derived from registration of TLC and RV images, e.g. functional small airways disease (fSAD%). Structural variables were assessed at TLC images, e.g. emphysema and airway wall thickness and diameter. We employed an unsupervised method for clustering. RESULTS: Four clusters were identified. Cluster 1 had relatively normal airway structures; Cluster 2 had an increase of fSAD% and wall thickness; Cluster 3 exhibited a further increase of fSAD% but a decrease of wall thickness and airway diameter; Cluster 4 had a significant increase of fSAD% and emphysema. Clinically, Cluster 1 showed normal FEV1/FVC and low exacerbations. Cluster 4 showed relatively low FEV1/FVC and high exacerbations. While Cluster 2 and Cluster 3 showed similar exacerbations, Cluster 2 had the highest BMI among all clusters. CONCLUSIONS: Association of imaging-based clusters with existing clinical metrics suggests the sensitivity of MICA in differentiating subpopulations.

Heterogeneous burden of lung disease in smokers with borderline airflow obstruction.

BACKGROUND: The identification of smoking-related lung disease in current and former smokers with normal FEV1 is complex, leading to debate regarding using a ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1/FVC) of less than 0.70 versus the predicted lower limit of normal (LLN) for diagnosis of airflow obstruction. We hypothesized that the discordant group of ever-smokers with FEV1/FVC between the LLN and 0.70 is heterogeneous, and aimed to characterize the burden of smoking-related lung disease in this group. METHODS: We compared spirometry, chest CT characteristics, and symptoms between 161 ever-smokers in the discordant group and 940 ever-smokers and 190 never-smokers with normal FEV1 and FEV1/FVC > 0.70 in the SPIROMICS cohort. We also estimated sensitivity and specificity for diagnosing objective radiographic evidence of chronic obstructive pulmonary disease (COPD) using different FEV1/FVC criteria thresholds. RESULTS: The discordant group had more CT defined emphysema and non-emphysematous gas trapping, lower post-bronchodilator FEV1 and FEF25-75, and higher respiratory medication use compared with the other two groups. Within the discordant group, 44% had radiographic CT evidence of either emphysema or non-emphysematous gas trapping; an FEV1/FVC threshold of 0.70 has greater sensitivity but lower specificity compared with LLN for identifying individuals with CT abnormality. CONCLUSIONS: Ever-smokers with normal FEV1 and FEV1/FVC <  0.70 but > LLN are a heterogeneous group that includes significant numbers of individuals with and without radiographic evidence of smoking-related lung disease. These findings emphasize the limitations of diagnosing COPD based on spirometric criteria alone.

Biomarkers Predictive of Exacerbations in the SPIROMICS and COPDGene Cohorts.

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

Relationship between quantitative radiographic assessments of interstitial lung disease and physiological and clinical features of systemic sclerosis.

OBJECTIVES: Extent of systemic sclerosis (SSc)-related interstitial lung disease (ILD) assessed from thoracic high-resolution CT (HRCT) predicts disease course, mortality and treatment response. While quantitative HRCT analyses of extent of lung fibrosis (QLFib) or total interstitial lung disease (QILD) are more sensitive and reproducible than visual HRCT assessments of SSc-ILD, these analyses are not widely available. This study evaluates the relationship between clinical disease parameters and QLFib and QILD scores to identify potential surrogate measures of radiographic extent of ILD. METHODS: Using baseline data from the Scleroderma Lung Study I (SLS I; N=158), multivariate regression analyses were performed using the best subset selection method to identify one to five variable models that best correlated with QLFib and QILD scores in both whole lung (WL) and the zone of maximal involvement (ZM). These models were subsequently validated using baseline data from SLS II (N=142). Bivariate analyses of the radiographic and clinical variables were also performed using pooled data. SLS I and II did not include patients with clinically significant pulmonary hypertension (PH). RESULTS: Diffusing capacity for carbon monoxide (DLCO) was the single best predictor of both QLF and QILD in the WL and ZM in all of the best subset models. Adding other disease parameters to the models did not substantially improve model performance. Forced vital capacity (FVC) did not predict QLF or QILD scores in any of the models. CONCLUSIONS: In the absence of PH, DLCO provides the best overall estimate of HRCT-measured lung disease in patients from two large SSc cohorts. FVC, although commonly used, may not be the best surrogate measure of extent of SSc-ILD at any point in time. TRIAL REGISTRATION NUMBERS: SLS I: www.clinicaltrials.gov NCT 00000-4563; SLS II: www.clinicaltrials.gov NCT 00883129.

Transitions to different patterns of interstitial lung disease in scleroderma with and without treatment.

OBJECTIVES: The aim is to investigate whether the 12-month quantitative changes in high-resolution CT (HRCT) measures of interstitial lung disease (ILD) are different, and to understand how they change, in patients with scleroderma-related ILD who receive drug therapy versus placebo. METHODS: HRCT images were acquired at baseline and at 12 months in 83 participants in Scleroderma Lung Study I, a clinical trial comparing treatment with oral cyclophosphamide versus placebo. A computer-aided model was used to quantify the extent of fibrotic reticulation, ground glass and honeycomb patterns and quantitative ILD (QILD: sum of these patterns) in the whole lung and the lung zone (upper, middle or lower) of maximal disease involvement. RESULTS: Mean QILD score decreased by 3.9% in the cyclophosphamide group while increasing by 4.2% in the placebo group in the most severe zone (p=0.01) and decreased by 3.2% in the cyclophosphamide group while increasing by 2.2% in the placebo group in the whole lung (p=0.03). Transitional probabilities demonstrated greater changes from a fibrotic to either a ground glass or normal pattern in the cyclophosphamide group and the reverse in the placebo group. CONCLUSIONS: Changes in quantitative HRCT measures of ILD provide a sensitive indication of disease progression and response to treatment. TRIAL REGISTRATION NUMBER: NCT00004563; Post-results.

Topographic diversity of the respiratory tract mycobiome and alteration in HIV and lung disease.

RATIONALE: Microbiome studies typically focus on bacteria, but fungal species are common in many body sites and can have profound effects on the host. Wide gaps exist in the understanding of the fungal microbiome (mycobiome) and its relationship to lung disease. OBJECTIVES: To characterize the mycobiome at different respiratory tract levels in persons with and without HIV infection and in HIV-infected individuals with chronic obstructive pulmonary disease (COPD). METHODS: Oral washes (OW), induced sputa (IS), and bronchoalveolar lavages (BAL) were collected from 56 participants. We performed 18S and internal transcribed spacer sequencing and used the neutral model to identify fungal species that are likely residents of the lung. We used ubiquity-ubiquity plots, random forest, logistic regression, and metastats to compare fungal communities by HIV status and presence of COPD. MEASUREMENTS AND MAIN RESULTS: Mycobiomes of OW, IS, and BAL shared common organisms, but each also had distinct members. Candida was dominant in OW and IS, but BAL had 39 fungal species that were disproportionately more abundant than in the OW. Fungal communities in BAL differed significantly by HIV status and by COPD, with Pneumocystis jirovecii significantly overrepresented in both groups. Other fungal species were also identified as differing in HIV and COPD. CONCLUSIONS: This study systematically examined the respiratory tract mycobiome in a relatively large group. By identifying Pneumocystis and other fungal species as overrepresented in the lung in HIV and in COPD, it is the first to determine alterations in fungal communities associated with lung dysfunction and/or HIV, highlighting the clinical relevance of these findings. Clinical trial registered with www.clinicaltrials.gov (NCT00870857).

Validation of cell-cycle arrest biomarkers for acute kidney injury using clinical adjudication.

RATIONALE: We recently reported two novel biomarkers for acute kidney injury (AKI), tissue inhibitor of metalloproteinases (TIMP)-2 and insulin-like growth factor binding protein 7 (IGFBP7), both related to G1 cell cycle arrest. OBJECTIVES: We now validate a clinical test for urinary [TIMP-2]·[IGFBP7] at a high-sensitivity cutoff greater than 0.3 for AKI risk stratification in a diverse population of critically ill patients. METHODS: We conducted a prospective multicenter study of 420 critically ill patients. The primary analysis was the ability of urinary [TIMP-2]·[IGFBP7] to predict moderate to severe AKI within 12 hours. AKI was adjudicated by a committee of three independent expert nephrologists who were masked to the results of the test. MEASUREMENTS AND MAIN RESULTS: Urinary TIMP-2 and IGFBP7 were measured using a clinical immunoassay platform. The primary endpoint was reached in 17% of patients. For a single urinary [TIMP-2]·[IGFBP7] test, sensitivity at the prespecified high-sensitivity cutoff of 0.3 (ng/ml)(2)/1,000 was 92% (95% confidence interval [CI], 85-98%) with a negative likelihood ratio of 0.18 (95% CI, 0.06-0.33). Critically ill patients with urinary [TIMP-2]·[IGFBP7] greater than 0.3 had seven times the risk for AKI (95% CI, 4-22) compared with critically ill patients with a test result below 0.3. In a multivariate model including clinical information, urinary [TIMP-2]·[IGFBP7] remained statistically significant and a strong predictor of AKI (area under the curve, 0.70, 95% CI, 0.63-0.76 for clinical variables alone, vs. area under the curve, 0.86, 95% CI, 0.80-0.90 for clinical variables plus [TIMP-2]·[IGFBP7]). CONCLUSIONS: Urinary [TIMP-2]·[IGFBP7] greater than 0.3 (ng/ml)(2)/1,000 identifies patients at risk for imminent AKI. Clinical trial registered with www.clinicaltrials.gov (NCT 01573962).

Assessing the validity of the RAND negative impact of asthma on quality of life short forms.

BACKGROUND: In response to recommendations from the 2010 National Institutes of Health Asthma Outcomes Workshop, we developed a system for measuring the negative impact of asthma on quality of life (QoL), which was referred to as the RAND Negative Impact of Asthma on Quality of Life (RAND-IAQL) item bank. The bank contains 65 items that focus on the patient's perception of the impact or bother of asthma on his or her life. OBJECTIVE: Evidence for the validity of 2 short forms, the RAND-IAQL 4-item and 12-item Short Forms, from the bank is presented. METHODS: Using a sample of 2032 adults with asthma, we validated our short forms against the Asthma Quality of Life Questionnaire-Marks (AQLQ-M), the Asthma Control Test, and generic measures of QoL developed by the Patient-reported Outcomes Measurement Information System (PROMIS). Discriminant validity was examined by comparing scores of respondents who differed according to multiple health indicators. RESULTS: Our sample ranged in age from 18 to 99 years (mean, 43 years), with 14% Hispanic, 11% Asian, 19% African American, and 56% non-Hispanic white race/ethnicity. Men had a significantly worse impact of asthma on QoL than women. The impact of asthma on QoL was greatest in African American and Hispanic subjects compared with that seen in non-Hispanic white subjects. Our measures correlated highly with the AQLQ-M and more strongly with the PROMIS global physical than mental scales. They differentiated between adults with asthma according to their perceived severity, level of control, presence or absence of exacerbations, and physical comorbidity. CONCLUSION: The RAND-IAQL item bank, measuring the impact of asthma on QoL, will complement other patient-reported outcomes, such as measures of asthma symptoms, functioning, and control.

Design of the Subpopulations and Intermediate Outcomes in COPD Study (SPIROMICS).

Subpopulations and Intermediate Outcomes in COPD Study (SPIROMICS) is a multicentre observational study of chronic obstructive pulmonary disease (COPD) designed to guide future development of therapies for COPD by providing robust criteria for subclassifying COPD participants into groups most likely to benefit from a given therapy during a clinical trial, and identifying biomarkers/phenotypes that can be used as intermediate outcomes to reliably predict clinical benefit during therapeutic trials. The goal is to enrol 3200 participants in four strata. Participants undergo a baseline visit and three annual follow-up examinations, with quarterly telephone calls. Adjudication of exacerbations and mortality will be undertaken.

Comparison of spatially matched airways reveals thinner airway walls in COPD. The Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study and the Subpopulations and Intermediate Outcomes in COPD Study (SPIROMICS).

BACKGROUND: COPD is characterised by reduced airway lumen dimensions and fewer peripheral airways. Most studies of airway properties sample airways based upon lumen dimension or at random, which may bias comparisons given reduced airway lumen dimensions and number in COPD. We sought to compare central airway wall dimensions on CT in COPD and controls using spatially matched airways, thereby avoiding selection bias of airways in the lung. METHODS: The Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study and Subpopulations and Intermediate Outcomes in COPD Study (SPIROMICS) recruited smokers with COPD and controls aged 50-79 years and 40-80 years, respectively. COPD was defined by current guidelines. Using CT image data, airway dimensions were measured for all central airway segments (generations 0-6) following 5 standardised paths into the lungs. Case-control airway comparisons were spatially matched by generation and adjusted for demographics, body size, smoking, CT dose, per cent emphysema, airway length and lung volume. RESULTS: Among 311 MESA COPD participants, airway wall areas at generations 3-6 were smaller in COPD compared with controls (all p<0.001). Among 1248 SPIROMICS participants, airway wall areas at generations 1-6 were smaller (all p<0.001), and this reduction was monotonic with increasing COPD severity (p<0.001). In both studies, sampling airways by lumen diameter or randomly resulted in a comparison of more proximal airways in COPD to more peripheral airways in controls (p<0.001) resulting in the appearance of thicker walls in COPD (p<0.02). CONCLUSIONS: Airway walls are thinner in COPD when comparing spatially matched central airways. Other approaches to airway sampling result in comparisons of more proximal to more distal airways and potentially biased assessment of airway properties in COPD.

The opportunity cost of futile treatment in the ICU*.

OBJECTIVE: When used to prolong life without achieving a benefit meaningful to the patient, critical care is often considered "futile." Although futile treatment is acknowledged as a misuse of resources by many, no study has evaluated its opportunity cost, that is, how it affects care for others. Our objective was to evaluate delays in care when futile treatment is provided. DESIGN: For 3 months, we surveyed critical care physicians in five ICUs to identify patients that clinicians identified as receiving futile treatment. We identified days when an ICU was full and contained at least one patient who was receiving futile treatment. For those days, we evaluated the number of patients waiting for ICU admission more than 4 hours in the emergency department or more than 1 day at an outside hospital. SETTING: One health system that included a quaternary care medical center and an affiliated community hospital. PATIENTS: Critically ill patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Boarding time in the emergency department and waiting time on the transfer list. Thirty-six critical care specialists made 6,916 assessments on 1,136 patients of whom 123 were assessed to receive futile treatment. A full ICU was less likely to contain a patient receiving futile treatment compared with an ICU with available beds (38% vs 68%, p < 0.001). On 72 (16%) days, an ICU was full and contained at least one patient receiving futile treatment. During these days, 33 patients boarded in the emergency department for more than 4 hours after admitted to the ICU team, nine patients waited more than 1 day to be transferred from an outside hospital, and 15 patients canceled the transfer request after waiting more than 1 day. Two patients died while waiting to be transferred. CONCLUSIONS: Futile critical care was associated with delays in care to other patients.

Comparison of serum, EDTA plasma and P100 plasma for luminex-based biomarker multiplex assays in patients with chronic obstructive pulmonary disease in the SPIROMICS study.

BACKGROUND: As a part of the longitudinal Chronic Obstructive Pulmonary Disease (COPD) study, Subpopulations and Intermediate Outcome Measures in COPD study (SPIROMICS), blood samples are being collected from 3200 subjects with the goal of identifying blood biomarkers for sub-phenotyping patients and predicting disease progression. To determine the most reliable sample type for measuring specific blood analytes in the cohort, a pilot study was performed from a subset of 24 subjects comparing serum, Ethylenediaminetetraacetic acid (EDTA) plasma, and EDTA plasma with proteinase inhibitors (P100). METHODS: 105 analytes, chosen for potential relevance to COPD, arranged in 12 multiplex and one simplex platform (Myriad-RBM) were evaluated in duplicate from the three sample types from 24 subjects. The reliability coefficient and the coefficient of variation (CV) were calculated. The performance of each analyte and mean analyte levels were evaluated across sample types. RESULTS: 20% of analytes were not consistently detectable in any sample type. Higher reliability and/or smaller CV were determined for 12 analytes in EDTA plasma compared to serum, and for 11 analytes in serum compared to EDTA plasma. While reliability measures were similar for EDTA plasma and P100 plasma for a majority of analytes, CV was modestly increased in P100 plasma for eight analytes. Each analyte within a multiplex produced independent measurement characteristics, complicating selection of sample type for individual multiplexes. CONCLUSIONS: There were notable detectability and measurability differences between serum and plasma. Multiplexing may not be ideal if large reliability differences exist across analytes measured within the multiplex, especially if values differ based on sample type. For some analytes, the large CV should be considered during experimental design, and the use of duplicate and/or triplicate samples may be necessary. These results should prove useful for studies evaluating selection of samples for evaluation of potential blood biomarkers.

Acute bronchodilator responses decline progressively over 4 years in patients with moderate to very severe COPD.

BACKGROUND: We previously reported a progressive decline in absolute responses of FEV1 and FVC to a near-maximal dose of 2 different short-acting bronchodilators over 4 years. Since varying host factors and the method of expressing the response may impact the time trend of acute bronchodilator responses, we now examined the potential influence of salient host characteristics on changes in bronchodilator responses over time expressed in different ways. METHODS: As part of the 4-year, placebo-controlled Understanding Potential Long-term Impacts on Function with Tiotropium (UPLIFT) trial, pre- and post-bronchodilator spirometry was performed at baseline and 1 month and every 6 months thereafter. Post-bronchodilator values for FEV1 and FVC were analyzed for subjects completing at least the 1 year visit (Placebo - N = 2463; Tiotropium - N = 2579), stratified by GOLD stage, age, gender and smoking status and expressed as absolute, relative (%) and % predicted changes from pre-bronchodilator values. Annual changes in bronchodilator response were estimated using linear mixed effects models. RESULTS: For all subjects analyzed, FEV1 and FVC bronchodilator responses showed progressive and highly significant (p < 0.0001) declines over 4 years. Declines were generally larger in patients with severe/very severe than mild/moderate airflow obstruction, in older patients (≥65 yrs) and in former than continuing smokers. CONCLUSION: Acute FEV1 and FVC responses to bronchodilators decline significantly over time in COPD patients, whether expressed as absolute, relative or % predicted changes, potentially impacting on the clinical responses to bronchodilator therapy as well as on the annual rate of decline in post-bronchodilator lung function. Clinicaltrials.gov number: NCT00144339.

Comparison of the respiratory microbiome in healthy nonsmokers and smokers.

RATIONALE: Results from 16S rDNA-encoding gene sequence-based, culture-independent techniques have led to conflicting conclusions about the composition of the lower respiratory tract microbiome. OBJECTIVES: To compare the microbiome of the upper and lower respiratory tract in healthy HIV-uninfected nonsmokers and smokers in a multicenter cohort. METHODS: Participants were nonsmokers and smokers without significant comorbidities. Oral washes and bronchoscopic alveolar lavages were collected in a standardized manner. Sequence analysis of bacterial 16S rRNA-encoding genes was performed, and the neutral model in community ecology was used to identify bacteria that were the most plausible members of a lung microbiome. MEASUREMENTS AND MAIN RESULTS: Sixty-four participants were enrolled. Most bacteria identified in the lung were also in the mouth, but specific bacteria such as Enterobacteriaceae, Haemophilus, Methylobacterium, and Ralstonia species were disproportionally represented in the lungs compared with values predicted by the neutral model. Tropheryma was also in the lung, but not the mouth. Mouth communities differed between nonsmokers and smokers in species such as Porphyromonas, Neisseria, and Gemella, but lung bacterial populations did not. CONCLUSIONS: This study is the largest to examine composition of the lower respiratory tract microbiome in healthy individuals and the first to use the neutral model to compare the lung to the mouth. Specific bacteria appear in significantly higher abundance in the lungs than would be expected if they originated from the mouth, demonstrating that the lung microbiome does not derive entirely from the mouth. The mouth microbiome differs in nonsmokers and smokers, but lung communities were not significantly altered by smoking.