Lung Function in Oil Spill Response Workers 1-3 Years After the Deepwater Horizon Disaster.

BACKGROUND: Little is known about the effects of inhalation exposures on lung function among workers involved in the mitigation of oil spills. Our objective was to determine the relationship between oil spill response work and lung function 1-3 years after the Deepwater Horizon (DWH) disaster. METHODS: We evaluated spirometry for 7,775 adults living in the Gulf states who either participated in DWH response efforts (workers) or received safety training but were not hired (nonworkers). At an enrollment interview, we collected detailed work histories including information on potential exposure to dispersants and burning oil/gas. We assessed forced expiratory volume in 1 second (FEV1; mL), forced vital capacity (FVC; mL), and the ratio (FEV1/FVC%) for differences by broad job classes and exposure to dispersants or burning oil/gas using multivariable linear and modified Poisson regression. RESULTS: We found no differences between workers and nonworkers. Among workers, we observed a small decrement in FEV1 (Beta, -71 mL; 95% confidence interval [CI], -127 to -14) in decontamination workers compared with support workers. Workers with high potential exposure to burning oil/gas had reduced lung function compared with unexposed workers: FEV1 (Beta, -183 mL; 95% CI, -316 to -49) and FEV1/FVC (Beta, -1.93%; 95% CI, -3.50 to -0.36), and an elevated risk of having a FEV1/FVC in the lowest tertile (prevalence ratio, 1.38; 95% CI, 0.99 to 1.92). CONCLUSIONS: While no differences in lung function were found between workers and nonworkers, lung function was reduced among decontamination workers and workers with high exposure to burning oil/gas compared with unexposed workers.

Phenotype of Spirometric Impairment in an Aging Population.

RATIONALE: The Global Lung Initiative (GLI) provides age-appropriate criteria for establishing spirometric impairment, including mild, moderate, and severe chronic obstructive pulmonary disease (COPD) and restrictive pattern, but its association with respiratory-related phenotypes has not been evaluated. OBJECTIVES: To evaluate respiratory-related phenotypes in GLI-defined spirometric impairment. METHODS: In COPDGene (N = 10,131 patients; age range, 45-81 yr; average smoking history, 44.3 pack-years), we evaluated spirometry, dyspnea (modified Medical Research Council grade, ≥2), poor respiratory health-related quality of life (St. George's Respiratory Questionnaire total score, ≥25), poor exercise performance (6-minute-walk distance, <391 m), bronchodilator reversibility (FEV1 change, >12% and ≥200 ml), and computed tomography-diagnosed emphysema and gas trapping (>5% and >15% of lung, respectively). MEASUREMENTS AND MAIN RESULTS: GLI established normal spirometry in 5,100 patients (50.3%), mild COPD in 669 (6.6%), moderate COPD in 865 (8.5%), severe COPD in 2,522 (24.9%), and restrictive pattern in 975 (9.6%). Relative to normal spirometry, graded associations with respiratory-related phenotypes were found for mild, moderate, and severe COPD, with respective adjusted odds ratios (95% confidence intervals) as follows: dyspnea-1.31 (1.10-1.56), 2.20 (1.81-2.68), and 10.73 (8.04-14.33); poor respiratory health-related quality of life-1.49 (1.28-1.75), 2.69 (2.08-3.47), and 14.61 (10.09-21.17); poor exercise performance-1.11 (0.94-1.31), 1.58 (1.33-1.88), and 4.58 (3.42-6.12); bronchodilator reversibility-2.76 (2.24-3.40), 5.18 (4.29-6.27), and 6.21 (5.06-7.62); emphysema-4.86 (3.16-7.47), 6.41 (4.09-10.05), and 17.79 (10.79-29.32); and gas trapping-3.92 (3.12-4.93), 5.20 (3.82-7.07), and 16.28 (9.71-27.30). Restrictive pattern was also associated with multiple respiratory-related phenotypes at a level similar to moderate COPD, but it was otherwise not associated with emphysema (0.89 [0.60-1.32]) or gas trapping (1.15 [0.92-1.42]). CONCLUSIONS: GLI-defined spirometric impairment establishes clinically meaningful respiratory disease, as validated by graded associations with respiratory-related phenotypes.

Comparison of NHANES III and ERS/GLI 12 for airway obstruction classification and severity.

The diagnosis and severity categorisation of obstructive lung disease is determined using reference values. The American Thoracic Society/European Respiratory Society in 2005 recommended the National Health and Nutrition Examination Survey (NHANES) III spirometry prediction equations for patients in USA aged 8-80 years. The Global Lung Initiative 2012 (GLI 12) provided spirometry prediction equations for patients aged 3-95 years. Comparison of the NHANES III and GLI 12 prediction equations for diagnosing and categorising airway obstruction in patients in USA has not been made.We aimed to quantify the differences between NHANES III and GLI 12 predicted values in Caucasians aged 18-95 years, using both mathematical simulation and clinical data. We compared predicted forced expiratory volume in 1 s (FEV1) and lower limit of normal (LLN) FEV1/forced vital capacity (FVC) % for NHANES III and GLI 12 prediction equations by applying both a simulation model and clinical spirometry data to quantify differences in the diagnosis and categorisation of airway obstruction.Mathematical simulation revealed significant similarities and differences between prediction equations for both LLN FEV1/FVC % and predicted FEV1 There are significant differences when using GLI 12 and NHANES III to diagnose airway obstruction and severity in Caucasian patients aged 18-95 years.Similarities and differences exist between NHANES III and GLI 12 for some age and height combinations. The differences in LLN FEV1/FVC % and predicted FEV1 are most prominent in older taller/shorter individuals. The magnitude of the differences can be large and may result in differences in clinical management.

Phenotype of normal spirometry in an aging population.

RATIONALE: In aging populations, the commonly used Global Initiative for Chronic Obstructive Lung Disease (GOLD) may misclassify normal spirometry as respiratory impairment (airflow obstruction and restrictive pattern), including the presumption of respiratory disease (chronic obstructive pulmonary disease [COPD]). OBJECTIVES: To evaluate the phenotype of normal spirometry as defined by a new approach from the Global Lung Initiative (GLI), overall and across GOLD spirometric categories. METHODS: Using data from COPDGene (n = 10,131; ages 45-81; smoking history, ≥10 pack-years), we evaluated spirometry and multiple phenotypes, including dyspnea severity (Modified Medical Research Council grade 0-4), health-related quality of life (St. George's Respiratory Questionnaire total score), 6-minute-walk distance, bronchodilator reversibility (FEV1 % change), computed tomography-measured percentage of lung with emphysema (% emphysema) and gas trapping (% gas trapping), and small airway dimensions (square root of the wall area for a standardized airway with an internal perimeter of 10 mm). MEASUREMENTS AND MAIN RESULTS: Among 5,100 participants with GLI-defined normal spirometry, GOLD identified respiratory impairment in 1,146 (22.5%), including a restrictive pattern in 464 (9.1%), mild COPD in 380 (7.5%), moderate COPD in 302 (5.9%), and severe COPD in none. Overall, the phenotype of GLI-defined normal spirometry included normal adjusted mean values for dyspnea grade (0.8), St. George's Respiratory Questionnaire (15.9), 6-minute-walk distance (1,424 ft [434 m]), bronchodilator reversibility (2.7%), % emphysema (0.9%), % gas trapping (10.7%), and square root of the wall area for a standardized airway with an internal perimeter of 10 mm (3.65 mm); corresponding 95% confidence intervals were similarly normal. These phenotypes remained normal for GLI-defined normal spirometry across GOLD spirometric categories. CONCLUSIONS: GLI-defined normal spirometry, even when classified as respiratory impairment by GOLD, included adjusted mean values in the normal range for multiple phenotypes. These results suggest that among adults with GLI-defined normal spirometry, GOLD may misclassify normal phenotypes as having respiratory impairment.

Variability of within-breath reactance in COPD patients and its association with dyspnoea.

The forced oscillation technique can identify expiratory flow limitation (EFL) when a large difference in inspiratory and expiratory reactance (ΔXrs) occurs. However, flow limitation can vary from breath to breath, and so we compared a multiple-breath ΔXrs approach to the traditional breath-by-breath assessment of EFL. We investigated the within- and between-day reproducibility and the factors that affect the size of ΔXrs when used as a continuous measurement over multiple breaths. In addition, we examined how multiple-breath ΔXrs relates to the sensation of breathlessness. 425 moderate to very severe chronic obstructive pulmonary disease (COPD) patients and 229 controls were included. Spirometry and impedance measurements were performed on a MasterScope CT Impulse Oscillation System. Median ΔXrs approached zero in healthy controls with little variation between measurements. COPD patients generally had higher ΔXrs and higher variability. The COPD patients with ΔXrs >0.1 kPa · L(-1) · s(-1) were prone to be more breathless and had a higher modified Medical Research Council dyspnoea scale score. In controls, the 95th percentile of ΔXrs was as low as 0.07 kPa · L(-1) · s(-1). We describe a new method to assess EFL at a patient level and propose a cut-off, mean ΔXrs >0.1 kPa · L(-1) · s(-1), as a way to identify COPD patients who are more likely to report dyspnoea.

Spirometric reference values for Malagasy adults aged 18-73 years.

The American Thoracic Society (ATS) and European Respiratory Society (ERS) recommend that spirometry prediction equations be derived from samples of similar race/ethnicity. Malagasy prediction equations do not exist. The objectives of this study were to establish prediction equations for healthy Malagasy adults, and then compare Malagasy measurements with published prediction equations. We enrolled 2491 healthy Malagasy subjects aged 18-73 years (1428 males) from June 2006 to April 2008. The subjects attempted to meet the ATS/ERS 2005 guidelines when performing forced expiratory spirograms. We compared Malagasy measurements of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC with predictions from the European Community for Steel and Coal (ECSC), the third National Health and Nutrition Examination Survey (NHANES III) and the ERS Global Lung Function Initiative (GLI) 2012 study. A linear model for the entire population, using age and height as independent variables, best predicted all spirometry parameters for sea level and highland subjects. FEV1, FVC and FEV1/FVC were most accurately predicted by NHANES III African-American male and female, and by GLI 2012 black male and black and South East Asian female equations. ECSC-predicted FEV1, FVC and FEV1/FVC were poorly matched to Malagasy measurements. We provide the first spirometry reference equations for a healthy adult Malagasy population, and the first comparison of Malagasy population measurements with ECSC, NHANES III and GLI 2012 prediction equations.

A genome-wide association study identifies risk loci for spirometric measures among smokers of European and African ancestry.

BACKGROUND: Pulmonary function decline is a major contributor to morbidity and mortality among smokers. Post bronchodilator FEV1 and FEV1/FVC ratio are considered the standard assessment of airflow obstruction. We performed a genome-wide association study (GWAS) in 9919 current and former smokers in the COPDGene study (6659 non-Hispanic Whites [NHW] and 3260 African Americans [AA]) to identify associations with spirometric measures (post-bronchodilator FEV1 and FEV1/FVC). We also conducted meta-analysis of FEV1 and FEV1/FVC GWAS in the COPDGene, ECLIPSE, and GenKOLS cohorts (total n = 13,532). RESULTS: Among NHW in the COPDGene cohort, both measures of pulmonary function were significantly associated with SNPs at the 15q25 locus [containing CHRNA3/5, AGPHD1, IREB2, CHRNB4] (lowest p-value = 2.17 × 10(-11)), and FEV1/FVC was associated with a genomic region on chromosome 4 [upstream of HHIP] (lowest p-value = 5.94 × 10(-10)); both regions have been previously associated with COPD. For the meta-analysis, in addition to confirming associations to the regions near CHRNA3/5 and HHIP, genome-wide significant associations were identified for FEV1 on chromosome 1 [TGFB2] (p-value = 8.99 × 10(-9)), 9 [DBH] (p-value = 9.69 × 10(-9)) and 19 [CYP2A6/7] (p-value = 3.49 × 10(-8)) and for FEV1/FVC on chromosome 1 [TGFB2] (p-value = 8.99 × 10(-9)), 4 [FAM13A] (p-value = 3.88 × 10(-12)), 11 [MMP3/12] (p-value = 3.29 × 10(-10)) and 14 [RIN3] (p-value = 5.64 × 10(-9)). CONCLUSIONS: In a large genome-wide association study of lung function in smokers, we found genome-wide significant associations at several previously described loci with lung function or COPD. We additionally identified a novel genome-wide significant locus with FEV1 on chromosome 9 [DBH] in a meta-analysis of three study populations.

Effect of barometric pressure on single-breath carbon monoxide diffusing capacity.

BACKGROUND: Single-breath diffusing capacity for carbon monoxide (DLCO) quantifies gas transfer in the lungs. DLCO measurement is affected by barometric pressure (Pb) and alveolar partial pressure of oxygen (PAO2). The current equations for adjusting DLCO for Pb and PAO2 may not be accurate given advances in test performance and technology. We quantify changes in DLCO with alterations in Pb in normal and COPD subjects, determine the accuracy of the current Pb and PAO2 adjustment equations and develop updated adjustment equations. METHODS: We measured DLCO in 13 normal and 10 COPD subjects at 1330 m altitude and in a hypobaric/hyperbaric chamber at altitudes of sea-level and 2500 m; six normal subjects were tested at 3600 m. We determined if there were significant differences in DLCO between altitudes. We developed an equation for adjusting DLCO for changes in Pb from sea-level. We compared this equation with the existing Pb adjustment equation in normal and COPD subjects. We determined the accuracy of the current PAO2 adjustment equation and developed a new PAO2 adjustment equation. RESULTS: DLCO significantly increased with decreasing Pb. We developed a Pb adjustment equation that adjusts DLCO measured at altitudes between 1330 m and 3600 m to sea-level values. This Pb adjustment equation yields DLCO results that are not significantly different than the currently recommended equation. We developed a more accurate PAO2 adjustment equation. CONCLUSION: DLCO measurement is significantly affected by altitude. We developed equations that accurately adjust DLCO for changes in Pb and PAO2 in normal and COPD subjects.

Diffusing Capacity and Mortality in Chronic Obstructive Pulmonary Disease.

Rationale: Chronic obstructive pulmonary disease (COPD) mortality risk is often estimated using the BODE (body mass index, obstruction, dyspnea, exercise capacity) index, including body mass index, forced expiratory volume in 1 second, dyspnea score, and 6-minute walk distance. Diffusing capacity of the lung for carbon monoxide (DlCO) is a potential predictor of mortality that reflects physiology distinct from that in the BODE index. Objectives: This study evaluated DlCO as a predictor of mortality using participants from the COPDGene study. Methods: We performed time-to-event analyses of individuals with COPD (former or current smokers with forced expiratory volume in 1 second/forced vital capacity < 0.7) and DlCO measurements from the COPDGene phase 2 visit. Cox proportional hazard methods were used to model survival, adjusting for age, sex, pack-years, smoking status, BODE index, computed tomography (CT) percent emphysema (low attenuation areas below -950 Hounsfield units), CT airway wall thickness, and history of cardiovascular or kidney diseases. C statistics for models with DlCO and BODE scores were used to compare discriminative accuracy. Results: Of 2,329 participants, 393 (16.8%) died during the follow-up period (median = 4.9 yr). In adjusted analyses, for every 10% decrease in DlCO percent predicted, mortality increased by 28% (hazard ratio = 1.28; 95% confidence interval, 1.17-1.41, P < 0.001). When compared with other clinical predictors, DlCO percent predicted performed similarly to BODE (C statistic DlCO = 0.68; BODE = 0.70), and the addition of DlCO to BODE improved its discriminative accuracy (C statistic = 0.71). Conclusions: Diffusing capacity, a measure of gas transfer, strongly predicted all-cause mortality in individuals with COPD, independent of BODE index and CT evidence of emphysema and airway wall thickness. These findings support inclusion of DlCO in prognostic models for COPD.

Long-term intersession variability for single-breath diffusing capacity.

BACKGROUND: Characterizing long-term diffusing capacity (DL(CO)) variability is important in assessing quality control for DL(CO) equipment and patient management. Long-term DL(CO) variability has not been reported. OBJECTIVES: It was the aim of this study to characterize long-term variability of DL(CO) in a cohort of biocontrols and to compare different methods of selecting a target value. METHODS: Longitudinal DL(CO) monitoring of biocontrols was performed as part of the inhaled insulin development program; 288 biocontrols were tested twice monthly for up to 5 years using a standardized technique. Variability, expressed either as percent change or DL(CO) units, was assessed using three different target values. RESULTS: The 90th percentile for mean intersession change in DL(CO) was between 10.9 and 15.8% (2.6-4.1 units) depending on the target value. Variability was lowest when the mean of all DL(CO) tests was used as the target value and highest when the baseline DL(CO) was used. The average of the first six DL(CO) tests provided an accurate estimate of the mean DL(CO) value. Using this target, the 90th percentile for mean intersession change was 12.3% and 3.0 units. Variability was stable over time and there were no meaningful associations between variability and demographic factors. CONCLUSIONS: DL(CO) biocontrol deviations >12% or >3.0 units, from the average of the first six tests, indicate that the instrument is not within quality control limits and should be carefully evaluated before further patient testing.

Haemoglobin as a biomarker for clinical outcomes in chronic obstructive pulmonary disease.

In COPD, anaemia is associated with increased morbidity, but the relationship between haemoglobin over its entire observed range and morbidity is poorly understood. Such an understanding could guide future therapeutic targeting of haemoglobin in COPD management. Leveraging the COPDGene study, we conducted a cross-sectional analysis of haemoglobin from COPD participants, examining symptoms, quality of life, functional performance, and acute exacerbations of COPD (AECOPD). Haemoglobin was analysed both as a continuous variable and categorised into anaemia, normal haemoglobin, and polycythaemia groups. Fractional polynomial modelling was used for continuous analyses; categorical models were multivariable linear or negative binomial regressions. Covariates included demographics, comorbidities, emphysema, diffusing capacity, and airflow obstruction. From 2539 participants, 366 (14%) were identified as anaemic and 125 (5%) as polycythaemic. Compared with normal haemoglobin, anaemia was significantly associated with increased symptoms (COPD Assessment Test score: p=0.006, modified Medical Research Council (mMRC) Dyspnoea Score: p=0.001); worse quality of life (St. George's Respiratory Questionnaire (SGRQ) score: p<0.001; Medical Outcomes Study Short Form 36-item Questionnaire (SF-36) General Health: p=0.002; SF-36 Physical Health: p<0.001), decreased functional performance (6-min walk distance (6MWD): p<0.001), and severe AECOPD (p=0.01), while polycythaemia was not. Continuous models, however, demonstrated increased morbidity at both ends of the haemoglobin distribution (p<0.01 for mMRC, SGRQ, SF-36 Physical Health, 6MWD, and severe AECOPD). Evaluating interactions, both diffusing capacity and haemoglobin were independently associated with morbidity. We present novel findings that haemoglobin derangements towards either extreme of the observed range are associated with increased morbidity in COPD. Further investigation is necessary to determine whether haemoglobin derangement drives morbidity or merely reflects systemic inflammation, and whether correcting haemoglobin towards the normal range improves morbidity.

Lung function in men with and without HIV.

OBJECTIVES: Initial studies suggest HIV-positive persons may be at increased risk for chronic lung diseases such as chronic obstructive pulmonary disease, but have commonly relied on single-center designs, lacked HIV-negative controls, or assessed lung function with only spirometry. We tested differences in spirometry and single-breath diffusing capacity for carbon monoxide (DLCO) in persons with and without HIV. DESIGN: Cross-sectional, observational study. METHODS: Participants were enrolled from the Multicenter AIDS Cohort Study, a longitudinal cohort study of men who have sex with men (both HIV-positive and HIV-negative) at four sites in the United States. Standardized spirometry and DLCO testing were performed in all eligible, consenting participants at routine study visits. We tested associations between HIV status and spirometry and DLCO results, using linear and logistic regression. RESULTS: Among 1067 men, median age was 57 years, prevalence of current marijuana (30%), and cigarette (24%) use was high, and another 45% were former cigarette smokers. Median forced expiratory volume in 1 s was 97% of predicted normal and DLCO was 85% of predicted normal. HIV-positive persons demonstrated no statistical difference in forced expiratory volume in 1 s compared with HIV-negative persons, but had worse DLCO (adjusted difference -2.6% of predicted; 95% confidence interval: -4.7 to -0.6%) and a higher risk of DLCO impairment (odds ratio for DLCO < 60% of predicted 2.97; 95% confidence interval: 1.36-6.47). Lower DLCO was associated with lower nadir CD4 cell counts. CONCLUSION: HIV-positive men are at increased risk of abnormal gas exchange, indicated by low DLCO, compared with men without HIV.

Intersession variability in single-breath diffusing capacity in diabetics without overt lung disease.

RATIONALE: American Thoracic Society guidelines state that a 10% or greater intersession change in diffusing capacity of the lung (DL(CO)) should be considered clinically significant. However, little is known about the short-term intersession variability in DL(CO) in untrained subjects or how variability is affected by rigorous external quality control. OBJECTIVES: To characterize the intersession variability of DL(CO) and the effect of different quality control methods in untrained individuals without significant lung disease. METHODS: Data were pooled from the comparator arms of 14 preregistration trials of inhaled insulin that included nonsmoking diabetic patients without significant lung disease. A total of 699 participants performed repeated DL(CO) measurements using a highly standardized technique. A total of 948 participants performed repeated measurements using routine clinical testing. MEASUREMENTS AND MAIN RESULTS: The mean intersession absolute change in DL(CO) using the highly standardized method was 1.45 ml/minute/mm Hg (5.64%) compared with 2.49 ml/minute/mm Hg (9.52%) in the routine testing group (P < 0.0001 for both absolute and percent difference). The variability in absolute intersession change in DL(CO) increased with increasing baseline DL(CO) values, whereas the absolute percentage of intersession change was stable across baseline values. Depending on the method, 15.5 to 35.5% of participants had an intersession change of 10% or greater. A 20% or greater threshold would reduce this percentage of patients to 1 to 10%. CONCLUSIONS: Intersession variability in DL(CO) measurement is dependent on the method of testing used and baseline DL(CO). Using a more liberal threshold to define meaningful intersession change may reduce the misclassification of normal variation as abnormal change.

Diffusing Capacity of Carbon Monoxide in Assessment of COPD.

BACKGROUND: 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. OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

International variation in the prevalence of COPD (the BOLD Study): a population-based prevalence study.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a growing cause of morbidity and mortality worldwide, and accurate estimates of the prevalence of this disease are needed to anticipate the future burden of COPD, target key risk factors, and plan for providing COPD-related health services. We aimed to measure the prevalence of COPD and its risk factors and investigate variation across countries by age, sex, and smoking status. METHODS: Participants from 12 sites (n=9425) completed postbronchodilator spirometry testing plus questionnaires about respiratory symptoms, health status, and exposure to COPD risk factors. COPD prevalence estimates based on the Global Initiative for Chronic Obstructive Lung Disease staging criteria were adjusted for the target population. Logistic regression was used to estimate adjusted odds ratios (ORs) for COPD associated with 10-year age increments and 10-pack-year (defined as the number of cigarettes smoked per day divided by 20 and multiplied by the number of years that the participant smoked) increments. Meta-analyses provided pooled estimates for these risk factors. FINDINGS: The prevalence of stage II or higher COPD was 10.1% (SE 4.8) overall, 11.8% (7.9) for men, and 8.5% (5.8) for women. The ORs for 10-year age increments were much the same across sites and for women and men. The overall pooled estimate was 1.94 (95% CI 1.80-2.10) per 10-year increment. Site-specific pack-year ORs varied significantly in women (pooled OR=1.28, 95% CI 1.15-1.42, p=0.012), but not in men (1.16, 1.12-1.21, p=0.743). INTERPRETATION: This worldwide study showed higher levels and more advanced staging of spirometrically confirmed COPD than have typically been reported. However, although age and smoking are strong contributors to COPD, they do not fully explain variations in disease prevalence-other factors also seem to be important. Although smoking cessation is becoming an increasingly urgent objective for an ageing worldwide population, a better understanding of other factors that contribute to COPD is crucial to assist local public-health officials in developing the best possible primary and secondary prevention policies for their regions.

Longitudinal association of body mass index with lung function: the CARDIA study.

BACKGROUND: Lung function at the end of life depends on its peak and subsequent decline. Because obesity is epidemic in young adulthood, we quantified age-related changes in lung function relative to body mass index (BMI). METHODS: The Coronary Artery Risk Development in Young Adults (CARDIA) study in 1985-86 (year 0) recruited 5,115 black and white men and women, aged 18-30. Spirometry testing was conducted at years 0, 2, 5 and 10. We estimated 10 year change in FVC, FEV1 and FEV1/FVC according to baseline BMI and change in BMI within birth cohorts with initial average ages 20, 24, and 28 years, controlling for race, sex, smoking, asthma, physical activity, and alcohol consumption. MEASUREMENTS AND MAIN RESULTS: Participants with baseline BMI < 21.3 kg/m2 experienced 10 year increases of 71 ml in FVC and 60 ml in FEV1 and neither measure declined through age 38. In contrast, participants with baseline BMI > or = 26.4 kg/m2 experienced 10 year decreases of 185 ml in FVC and 64 ml in FEV1. FEV1/FVC increased with increasing BMI. Weight gain was also associated with lung function. Those who gained the most weight over 10 years had the largest decrease in FVC, but FVC increased with weight gain in those initially thinnest. In contrast, FEV1 decreased with increasing weight gain in all participants, with maximum decline in obese individuals who gained the most weight during the study. CONCLUSION: Among healthy young adults, increasing BMI in the initially thin participants was associated with increasing then stable lung function through age 38, but there were substantial lung function losses with higher and increasing fatness. These results suggest that the obesity epidemic threatens the lung health of the general population.

Airflow Obstruction Categorization Methods and Mortality.

RATIONALE: Current guidelines recommend using forced expiratory volume in 1 second (FEV1) % predicted to categorize the severity of airflow obstruction. There are limitations to using FEV1 % predicted for this purpose, including bias associated with demographic factors and the inability to correct for "lung size." Other methods for grading the severity of airflow obstruction have been proposed to address these limitations. OBJECTIVES: Our objectives were to categorize airflow obstruction severity using these methods and then determine which method results in a categorization most closely associated with mortality. METHODS: Study subjects were patients aged 40-80 years tested in our pulmonary function test laboratories in the period 2002 to 2013 with airflow obstruction based on an FEV1/forced vital capacity (FVC) less than the lower limit of normal. Categorization of airflow obstruction severity was determined using four methods: FEV1 % predicted; FEV1 % predicted adjusted by FVC % predicted; FEV1/FVC confidence interval approach; and FEV1 z-scores. Receiver operating characteristic curve analysis was used to determine which categorization method best predicts 5-year survival. RESULTS: We identified 2,000 patients with airflow obstruction. Important differences in the categorization of airflow obstruction severity were observed using the different methods. More patients were categorized as having severe obstruction using FEV1 % predicted and FEV1 z-scores compared with FEV1 % predicted adjusted by FVC % predicted and FEV1/FVC confidence interval approach. FEV1 % predicted was the best predictor of 5-year survival among the four methods studied. CONCLUSIONS: In our study, categorizing airflow obstruction severity using FEV1 % predicted best predicted 5-year survival. This validates the current guideline recommendation that FEV1 % predicted be used to categorize the severity of airflow obstruction.

Exposure to Oil Spill Chemicals and Lung Function in Deepwater Horizon Disaster Response Workers.

OBJECTIVE: The aim of this study was to assess the relationship between total hydrocarbon (THC) exposures attributed to oil spill clean-up work and lung function 1 to 3 years after the Deepwater Horizon (DWH) disaster. METHODS: We used data from the GuLF STUDY, a large cohort of adults who worked on response to the DWH disaster and others who were safety trained but did not work. We analyzed data from 6288 workers with two acceptable spirometry tests. We estimated THC exposure levels with a job exposure matrix. We evaluated lung function using the forced expiratory volume in 1 second (FEV1; mL), the forced vital capacity (FVC; mL), and the FEV1/FVC ratio (%). RESULTS: Lung function measures did not differ by THC exposure levels among clean-up workers. CONCLUSION: We did not observe an association between THC exposure and lung function among clean-up workers 1 to 3 years following the DWH disaster.

Relationship of BMPR2 mutations to vasoreactivity in pulmonary arterial hypertension.

BACKGROUND: Vasoreactivity tests are fundamental in evaluating pulmonary arterial hypertension (PAH). Mutations of the transforming growth factor-beta type II receptor gene, BMPR2, predispose to the development of pulmonary hypertension and may alter the response to vasodilators. Previous investigations have not examined the relationship of BMPR2 mutations to vasoreactivity. METHODS AND RESULTS: We identified 133 consecutive unrelated patients with either idiopathic or familial PAH. Sixty-six patients were excluded because we lacked either DNA samples (n=18) or complete data from a vasoreactivity test (n=48). The remaining 67 patients were screened for BMPR2 DNA sequence variations, and specific variations were confirmed by gene sequencing. The vasoreactivity of patients with nonsynonymous BMPR2 variations was compared with that of patients without nonsynonymous BMPR2 variations. We found nonsynonymous BMPR2 variations in 27 of 67 patients with idiopathic (n=16 of 52) or familial (n=11 of 15) PAH. Vasoreactivity was identified in 3.7% of 27 patients with nonsynonymous BMPR2 variations and in 35% of 40 patients without nonsynonymous BMPR2 variations (P=0.003). Five of the 27 nonsynonymous variations occur commonly in healthy individuals. None of the remaining 22 patients with BMPR2 variations demonstrated vasoreactivity, and the analysis remained unchanged when we assumed that nonsynonymous BMPR2 variations were present in all 15 patients with familial PAH. CONCLUSIONS: Patients with familial or idiopathic PAH and nonsynonymous BMPR2 variations are unlikely to demonstrate vasoreactivity. Further trials are required to determine whether long-term therapy can be directed by tests for BMPR2 variations.

Instrument accuracy and reproducibility in measurements of pulmonary function.

BACKGROUND: The objective of the study was to quantify the accuracy and reproducibility of five commercially available pulmonary function test (PFT) instruments (Collins CPL [Ferraris Respiratory; Louisville, CO]; Morgan Transflow Test PFT System [Morgan Scientific; Haverhill, MA]; SensorMedics Vmax 22D [VIASYS Healthcare; Yorba Linda, CA]; Jaeger USA Masterscreen Diffusion TP [VIASYS Healthcare]; and Medical Graphics Profiler DX System [Medical Graphics Corp; St. Paul, MN]) that are associated with spirometry and the measurement of pulmonary diffusing capacity. METHODS: In a multifactor, single-center, repeated-measures, full factorial 90-day study, a pulmonary waveform generator and a single-breath simulator of diffusing capacity of the lung for carbon monoxide (Dlco) were used to perform simulations of FVC and Dlco maneuvers. Accuracy was assessed as the difference between the observed and simulated values. Reproducibility was determined as the coefficient of variation of all measurements made during the study. RESULTS: All instruments demonstrated a high degree of accuracy in the measurement of FVC and FEV(1). Overall, the accuracies associated with the measurement of peak flow, forced expiratory flow, mid-expiratory phase, and diffusing capacity were generally lower and more variable among the instruments tested. The coefficients of variation of Dlco measurements over 90 days were higher than those observed for spirometry. CONCLUSIONS: This study demonstrates the feasibility of assessing the accuracy and reproducibility of modern PFT instruments using simulation testing. Our results provide an assessment of the component of PFT accuracy and reproducibility that is due to instrumentation alone.