Spirometry, Static Lung Volumes, and Diffusing Capacity

BACKGROUND

Spirometric Z-scores from the Global Lung Initiative (GLI) rigorously account for age-related changes in lung function and are thus age-appropriate when establishing spirometric impairments, including a restrictive pattern and air-flow obstruction. However, GLI-defined spirometric impairments have not yet been evaluated regarding associations with static lung volumes (total lung capacity [TLC], functional residual capacity [FRC], and residual volume [RV]) and gas exchange (diffusing capacity).

METHODS

We performed a retrospective review of pulmonary function tests in subjects ≥40 y old (mean age 64.6 y), including pre-bronchodilator measures for: spirometry (n = 2,586), static lung volumes by helium dilution with inspiratory capacity maneuver (n = 2,586), and hemoglobin-adjusted single-breath diffusing capacity (n = 2,508). Using multivariable linear regression, adjusted least-squares means (adj_LSMeans) were calculated for TLC, FRC, RV, and hemoglobin-adjusted single-breath diffusing capacity. The adj_LSMeans were expressed with and without height-cubed standardization and stratified by GLI-defined spirometry, including normal (n = 1,251), restrictive pattern (n = 663), and air-flow obstruction (mild, [n = 128]; moderate, [n = 150]; and severe, [n = 394]).

RESULTS

Relative to normal spirometry, restrictive-pattern had lower adj_LSMeans for TLC, FRC, RV, and hemoglobin-adjusted single-breath diffusing capacity (P ≤ .001). Conversely, relative to normal spirometry, mild, moderate, and severe air-flow obstruction had higher adj_LSMeans for FRC and RV (P < .001). However, only mild and moderate air-flow obstruction had higher adj_LSMeans for TLC (P < .001), while only moderate and severe air-flow obstruction had higher adj_LSMeans for RV/TLC (P < .001) and lower adj_LSMeans for hemoglobin-adjusted single-breath diffusing capacity (P < .001). Notably, TLC (calculated as FRC + inspiratory capacity) was not increased in severe air-flow obstruction (P ≥ .11) because inspiratory capacity decreased with increasing air-flow obstruction (P < .001), thus opposing the increased FRC (P < .001). Finally, P values were similar whether adj_LSMeans were height-cubed standardized.

CONCLUSIONS

A GLI-defined spirometric restrictive pattern is strongly associated with a restrictive ventilatory defect (decreased TLC, FRC, and RV), while GLI-defined spirometric air-flow obstruction is strongly associated with hyperinflation (increased FRC) and air trapping (increased RV and RV/TLC). Both spirometric impairments were strongly associated with impaired gas exchange (decreased hemoglobin-adjusted single-breath diffusing capacity).

Association between Functional Small Airway Disease and FEV1 Decline in Chronic Obstructive Pulmonary Disease

RATIONALE

The small conducting airways are the major site of airflow obstruction in chronic obstructive pulmonary disease and may precede emphysema development.

OBJECTIVES

We hypothesized a novel computed tomography (CT) biomarker of small airway disease predicts FEV1 decline.

METHODS

We analyzed 1,508 current and former smokers from COPDGene with linear regression to assess predictors of change in FEV1 (ml/yr) over 5 years. Separate models for subjects without and with airflow obstruction were generated using baseline clinical and physiologic predictors in addition to two novel CT metrics created by parametric response mapping (PRM), a technique pairing inspiratory and expiratory CT images to define emphysema (PRM(emph)) and functional small airways disease (PRM(fSAD)), a measure of nonemphysematous air trapping.

MEASUREMENTS AND MAIN RESULTS

Mean (SD) rate of FEV1 decline in ml/yr for GOLD (Global Initiative for Chronic Obstructive Lung Disease) 0-4 was as follows: 41.8 (47.7), 53.8 (57.1), 45.6 (61.1), 31.6 (43.6), and 5.1 (35.8), respectively (trend test for grades 1-4; P < 0.001). In multivariable linear regression, for participants without airflow obstruction, PRM(fSAD) but not PRM(emph) was associated with FEV1 decline (P < 0.001). In GOLD 1-4 participants, both PRM(fSAD) and PRM(emph) were associated with FEV1 decline (P < 0.001 and P = 0.001, respectively). Based on the model, the proportional contribution of the two CT metrics to FEV1 decline, relative to each other, was 87% versus 13% and 68% versus 32% for PRM(fSAD) and PRM(emph) in GOLD 1/2 and 3/4, respectively.

CONCLUSIONS

CT-assessed functional small airway disease and emphysema are associated with FEV1 decline, but the association with functional small airway disease has greatest importance in mild-to-moderate stage chronic obstructive pulmonary disease where the rate of FEV1 decline is the greatest. Clinical trial registered with www.clinicaltrials.gov (NCT 00608764).

Effect of beta-blockers on exacerbation rate and lung function in chronic obstructive pulmonary disease (COPD)

BACKGROUND

Beta-blockers are commonly prescribed for patients with cardiovascular disease. Providers have been wary of treating chronic obstructive pulmonary disease (COPD) patients with beta-blockers due to concern for bronchospasm, but retrospective studies have shown that cardio-selective beta-blockers are safe in COPD and possibly beneficial. However, these benefits may reflect symptom improvements due to the cardiac effects of the medication. The purpose of this study is to evaluate associations between beta-blocker use and both exacerbation rates and longitudinal measures of lung function in two well-characterized COPD cohorts.

METHODS

We retrospectively analyzed 1219 participants with over 180 days of follow up from the STATCOPE trial, which excluded most cardiac comorbidities, and from the placebo arm of the MACRO trial. Primary endpoints were exacerbation rates per person-year and change in spirometry over time in association with beta blocker use.

RESULTS

Overall 13.9% (170/1219) of participants reported taking beta-blockers at enrollment. We found no statistically significant differences in exacerbation rates with respect to beta-blocker use regardless of the prevalence of cardiac comorbidities. In the MACRO cohort, patients taking beta-blockers had an exacerbation rate of 1.72/person-year versus a rate of 1.71/person-year in patients not taking beta-blockers. In the STATCOPE cohort, patients taking beta-blockers had an exacerbation rate of 1.14/person-year. Patients without beta-blockers had an exacerbation rate of 1.34/person-year. We found no detrimental effect of beta blockers with respect to change in lung function over time.

CONCLUSION

We found no evidence that beta-blocker use was unsafe or associated with worse pulmonary outcomes in study participants with moderate to severe COPD.

Body mass index change in gastrointestinal cancer and chronic obstructive pulmonary disease is associated with Dedicator of Cytokinesis 1

BACKGROUND

There have been a number of candidate gene association studies of cancer cachexia-related traits, but no genome-wide association study (GWAS) has been published to date. Cachexia presents in patients with a number of complex traits, including both cancer and COPD. The objective of the current investigation was to search for a shared genetic aetiology for change in body mass index (ΔBMI) among cancer and COPD by using GWAS data in the Framingham Heart Study.

METHODS

A linear mixed effects model accounting for age, sex, and change in smoking status was used to calculate ΔBMI in participants over 40 years of age with three consecutive BMI time points (n = 4162). Four GWAS of ΔBMI using generalized estimating equations were performed among 1085 participants with a cancer diagnosis, 204 with gastrointestinal (GI) cancer, 112 with lung cancer, and 237 with COPD to test for association with 418 365 single-nucleotide polymorphisms (SNPs).

RESULTS

Two SNPs reached a level of genome-wide significance (P < 5 × 10^-8 ) with ΔBMI: (i) rs41526344 within the CNTN4 gene, among COPD cases (β = 0.13, P = 4.3 × 10^-8 ); and (ii) rs4751240 in the gene Dedicator of Cytokinesis 1 (DOCK1) among GI cancer cases (β = 0.10, P = 1.9 × 10^-8 ). The DOCK1 SNP association replicated in the ΔBMI GWAS among COPD cases (β_meta-analyis  = 0.10, P_meta-analyis  = 9.3 × 10^-10 ). The DOCK1 gene codes for the dedicator of cytokinesis 1 protein, which has a role in myoblast fusion.

CONCLUSIONS

In sum, one statistically significant common variant in the DOCK1 gene was associated with ΔBMI in GI cancer and COPD cases providing support for at least partially shared aetiology of ΔBMI in complex diseases.

Effects of combined tiotropium/olodaterol on inspiratory capacity and exercise endurance in COPD

Two replicate, double-blind, 6-week, incomplete-crossover studies (MORACTO 1 and 2) assessed the effects of tiotropium/olodaterol on inspiratory capacity and exercise endurance time in patients with moderate to severe chronic obstructive pulmonary disease.For each patient, four of five treatments were administered once daily for 6 weeks, with a 21-day washout between treatments: tiotropium/olodaterol 2.5/5 µg or 5/5 µg, tiotropium 5 µg, olodaterol 5 µg or placebo, all via the Respimat inhaler. Primary outcomes were inspiratory capacity prior to exercise and exercise endurance time during constant work-rate cycle ergometry to symptom limitation at 75% of peak incremental work rate after 6 weeks (2 h post-dose).295 and 291 patients were treated in MORACTO 1 and 2, respectively. Tiotropium/olodaterol 2.5/5 and 5/5 µg provided significant improvements in inspiratory capacity versus placebo and monotherapies (p<0.0001), and significant improvements in exercise endurance time versus placebo (p<0.0001). Intensity of breathing discomfort was reduced following both doses of tiotropium/olodaterol versus placebo (p<0.0001).Once-daily tiotropium/olodaterol yielded improvements in lung hyperinflation versus placebo and statistically significant improvements versus monotherapies. Tiotropium/olodaterol also showed improvements in dyspnoea and exercise tolerance versus placebo but not consistently versus monotherapies.

Patient Involvement in the Design of a Patient-Centered Clinical Trial to Promote Adherence to Supplemental Oxygen Therapy in COPD

BACKGROUND

Patients are increasingly viewed as key stakeholders who can contribute in meaningful ways to clinical research and are emphasized in research funded by the Patient-Centered Outcomes Research Institute (PCORI). We are not aware of other peer-reviewed publications that report methods and outcomes of patient engagement to refine study design for a PCORI-sponsored clinical effectiveness trial.

OBJECTIVE

The aim of this report was to describe the process and outcomes of involving patients in the design of a clinical trial to promote adherence to supplemental oxygen therapy among patients with chronic obstructive pulmonary disease.

METHODS

In-person focus groups and individual discussions via telephone and email were used to elicit feedback to refine the intervention and clarify outcomes of highest importance to patients.

RESULTS

A total of 25 patients and five caregivers provided feedback. Their feedback has informed decisions regarding the length of intervention sessions (20 min and in some cases longer was acceptable), the importance of including caregivers, and discussion topics (e.g., social discomfort about using oxygen in public, identifying personally relevant reasons to use oxygen, pulmonary rehabilitation). Multiple outcomes were rated as highly important to patients (physical function, fatigue, sleep, anxiety, depression, and ability to participate in social roles and activities), and the outcome that was ranked as most important varied by individual. Therefore, multiple patient-reported outcomes will be used as endpoints for the clinical trial.

CONCLUSIONS

Patient involvement led to refinements of the intervention and clinical trial endpoints to better address the expressed needs and concerns of patients and caregivers.

Clinical, physiologic, and radiographic factors contributing to development of hypoxemia in moderate to severe COPD: a cohort study

Background

Hypoxemia is a major complication of COPD and is a strong predictor of mortality. We previously identified independent risk factors for the presence of resting hypoxemia in the COPDGene cohort. However, little is known about characteristics that predict onset of resting hypoxemia in patients who are normoxic at baseline. We hypothesized that a combination of clinical, physiologic, and radiographic characteristics would predict development of resting hypoxemia after 5-years of follow-up in participants with moderate to severe COPD

Methods

We analyzed 678 participants with moderate-to-severe COPD recruited into the COPDGene cohort who completed baseline and 5-year follow-up visits and who were normoxic by pulse oximetry at baseline. Development of resting hypoxemia was defined as an oxygen saturation ≤88% on ambient air at rest during follow-up. Demographic and clinical characteristics, lung function, and radiographic indices were analyzed with logistic regression models to identify predictors of the development of hypoxemia.

Results

Forty-six participants (7%) developed resting hypoxemia at follow-up. Enrollment at Denver (OR 8.30, 95%CI 3.05–22.6), lower baseline oxygen saturation (OR 0.70, 95%CI 0.58–0.85), self-reported heart failure (OR 6.92, 95%CI 1.56–30.6), pulmonary artery (PA) enlargement on computed tomography (OR 2.81, 95%CI 1.17–6.74), and prior severe COPD exacerbation (OR 3.31, 95%CI 1.38–7.90) were independently associated with development of resting hypoxemia. Participants who developed hypoxemia had greater decline in 6-min walk distance and greater 5-year decline in quality of life compared to those who remained normoxic at follow-up.

Conclusions

Development of clinically significant hypoxemia over a 5-year span is associated with comorbid heart failure, PA enlargement and severe COPD exacerbation. Further studies are needed to determine if treatments targeting these factors can prevent new onset hypoxemia.

Trial registration

COPDGene is registered at ClinicalTrials.gov: NCT00608764 (Registration Date: January 28, 2008)

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0331-0) contains supplementary material, which is available to authorized users.

A Randomized Trial of Long-Term Oxygen for COPD with Moderate Desaturation

BACKGROUND

Long-term treatment with supplemental oxygen has unknown efficacy in patients with stable chronic obstructive pulmonary disease (COPD) and resting or exercise-induced moderate desaturation.

METHODS

We originally designed the trial to test whether long-term treatment with supplemental oxygen would result in a longer time to death than no use of supplemental oxygen among patients who had stable COPD with moderate resting desaturation (oxyhemoglobin saturation as measured by pulse oximetry [Spo₂], 89 to 93%). After 7 months and the randomization of 34 patients, the trial was redesigned to also include patients who had stable COPD with moderate exercise-induced desaturation (during the 6-minute walk test, Spo₂ ≥80% for ≥5 minutes and <90% for ≥10 seconds) and to incorporate the time to the first hospitalization for any cause into the new composite primary outcome. Patients were randomly assigned, in a 1:1 ratio, to receive long-term supplemental oxygen (supplemental-oxygen group) or no long-term supplemental oxygen (no-supplemental-oxygen group). In the supplemental-oxygen group, patients with resting desaturation were prescribed 24-hour oxygen, and those with desaturation only during exercise were prescribed oxygen during exercise and sleep. The trial-group assignment was not masked.

RESULTS

A total of 738 patients at 42 centers were followed for 1 to 6 years. In a time-to-event analysis, we found no significant difference between the supplemental-oxygen group and the no-supplemental-oxygen group in the time to death or first hospitalization (hazard ratio, 0.94; 95% confidence interval [CI], 0.79 to 1.12; P=0.52), nor in the rates of all hospitalizations (rate ratio, 1.01; 95% CI, 0.91 to 1.13), COPD exacerbations (rate ratio, 1.08; 95% CI, 0.98 to 1.19), and COPD-related hospitalizations (rate ratio, 0.99; 95% CI, 0.83 to 1.17). We found no consistent between-group differences in measures of quality of life, lung function, and the distance walked in 6 minutes.

CONCLUSIONS

In patients with stable COPD and resting or exercise-induced moderate desaturation, the prescription of long-term supplemental oxygen did not result in a longer time to death or first hospitalization than no long-term supplemental oxygen, nor did it provide sustained benefit with regard to any of the other measured outcomes. (Funded by the National Heart, Lung, and Blood Institute and the Centers for Medicare and Medicaid Services; LOTT ClinicalTrials.gov number, NCT00692198 .).

Exercise, ageing and the lung

This review provides a pulmonary-focused description of the age-associated changes in the integrative physiology of exercise, including how declining lung function plays a role in promoting multimorbidity in the elderly through limitation of physical function. We outline the ageing of physiological systems supporting endurance activity: 1) coupling of muscle metabolism to mechanical power output; 2) gas transport between muscle capillary and mitochondria; 3) matching of muscle blood flow to its requirement; 4) oxygen and carbon dioxide carrying capacity of the blood; 5) cardiac output; 6) pulmonary vascular function; 7) pulmonary oxygen transport; 8) control of ventilation; and 9) pulmonary mechanics and respiratory muscle function. Deterioration in function occurs in many of these systems in healthy ageing. Between the ages of 25 and 80 years pulmonary function and aerobic capacity each decline by ∼40%. While the predominant factor limiting exercise in the elderly likely resides within the function of the muscles of ambulation, muscle function is (at least partially) rescued by exercise training. The age-associated decline in pulmonary function, however, is not recovered by training. Thus, loss in pulmonary function may lead to ventilatory limitation in exercise in the active elderly, limiting the ability to accrue the health benefits of physical activity into senescence.

Skeletal muscle power and fatigue at the tolerable limit of ramp-incremental exercise in COPD

Muscle fatigue (a reduced power for a given activation) is common following exercise in chronic obstructive pulmonary disease (COPD). Whether muscle fatigue, and reduced maximal voluntary locomotor power, are sufficient to limit whole body exercise in COPD is unknown. We hypothesized in COPD: 1) exercise is terminated with a locomotor muscle power reserve; 2) reduction in maximal locomotor power is related to ventilatory limitation; and 3) muscle fatigue at intolerance is less than age-matched controls. We used a rapid switch from hyperbolic to isokinetic cycling to measure the decline in peak isokinetic power at the limit of incremental exercise ("performance fatigue") in 13 COPD patients (FEV₁ 49 ± 17%pred) and 12 controls. By establishing the baseline relationship between muscle activity and isokinetic power, we apportioned performance fatigue into the reduction in muscle activation and muscle fatigue. Peak isokinetic power at intolerance was ~130% of peak incremental power in controls (274 ± 73 vs. 212 ± 84 W, P < 0.05), but ~260% in COPD patients (187 ± 141 vs. 72 ± 34 W, P < 0.05), greater than controls (P < 0.05). Muscle fatigue as a fraction of baseline peak isokinetic power was not different in COPD patients vs. controls (0.11 ± 0.20 vs. 0.19 ± 0.11). Baseline to intolerance, the median frequency of maximal isokinetic muscle activity, was unchanged in COPD patients but reduced in controls (+4.3 ± 11.6 vs. -5.5 ± 7.6%, P < 0.05). Performance fatigue as a fraction of peak incremental power was greater in COPD vs. controls and related to resting (FEV₁/FVC) and peak exercise (V̇_E/maximal voluntary ventilation) pulmonary function (r² = 0.47 and 0.55, P < 0.05). COPD patients are more fatigable than controls, but this fatigue is insufficient to constrain locomotor power and define exercise intolerance.

Relation of concavity in the expiratory flow-volume loop to dynamic hyperinflation during exercise in COPD

Active expiration during exercise can increase intrathoracic pressure yielding concavity in the expiratory flow-volume loop in COPD. We investigated the relationship between this concavity and dynamic hyperinflation (DH). 17 COPD patients (FEV₁: 38±10%pred, GOLD stage 3-4) and 12 healthy subjects performed cycle ergometer incremental exercise. Expiratory limb of the spontaneous flow-volume loop was analyzed breath-by-breath using a geometric approach (rectangular area ratio (RAR), Respir. Med., 104(3):389-96, 2010). RAR below 0.5 demonstrates expiratory limb concavity. DH was determined with serial inspiratory capacity maneuvers. 5 of 17 patients displayed little end-exercise concavity (RAR=0.52±0.04, group LCONC). 12 patients had concavity at rest and end-exercise RAR reached 0.40±0.03 (group HCONC). Healthy subjects showed no concavity. End-exercise RAR correlated with resting FEV₁%pred (R²=0.81, P<0.05). Group HCONC, compared to groups LCONC and H, reached significantly lower work rate, minute ventilation, and more dyspnea. DH inversely correlated with RAR (R²=0.81, P<0.05). Detection of concavity in spontaneous flow-volume loops may help assess DH and exercise limitation in COPD.

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.

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.

A Novel Spirometric Measure Identifies Mild COPD Unidentified by Standard Criteria

BACKGROUND

In chronic obstructive pulmonary disease, both smaller and larger airways are affected. FEV₁ mainly reflects large airways obstruction, while the later fraction of forced exhalation reflects reduction in terminal expiratory flow. In this study, the objective was to evaluate the relationship between spirometric ratios, including the ratio of forced expiratory volume in 3 and 6 seconds (FEV₃/FEV₆), and small airways measures and gas trapping at quantitative chest CT scanning, and clinical outcomes in the Genetic Epidemiology of COPD (COPDGene) cohort.

METHODS

Seven thousand eight hundred fifty-three current and ex-smokers were evaluated for airflow obstruction by using recently defined linear iteratively derived equations of Hansen et al to determine lower limit of normal (LLN) equations for prebronchodilator FEV₁/FVC, FEV₁/FEV₆, FEV₃/FEV₆, and FEV₃/FVC. General linear and ordinal regression models were applied to the relationship between prebronchodilator spirometric and radiologic and clinical data.

RESULTS

Of the 10,311 participants included in the COPDGene phase I study, participants with incomplete quantitative CT scanning or relevant spirometric data were excluded, resulting in 7,853 participants in the present study. Of 4,386 participants with FEV₁/FVC greater than or equal to the LLN, 15.4% had abnormal FEV₃/FEV₆. Compared with normal FEV₃/FEV₆ and FEV₁/FVC, abnormal FEV₃/FEV₆ was associated with significantly greater gas trapping; St. George's Respiratory Questionnaire score; modified Medical Research Council dyspnea score; and BMI, airflow obstruction, dyspnea, and exercise index and with shorter 6-min walking distance (all P < .0001) but not with CT scanning evidence of emphysema.

CONCLUSIONS

Current and ex-smokers with prebronchodilator FEV₃/FEV₆ less than the LLN as the sole abnormality identifies a distinct population with evidence of small airways disease in quantitative CT scanning, impaired indexes of physical function and quality of life otherwise deemed normal by using the current spirometric definition.

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.

Use of exercise testing in the evaluation of interventional efficacy: an official ERS statement

This document reviews 1) the measurement properties of commonly used exercise tests in patients with chronic respiratory diseases and 2) published studies on their utilty and/or evaluation obtained from MEDLINE and Cochrane Library searches between 1990 and March 2015.

Exercise tests are reliable and consistently responsive to rehabilitative and pharmacological interventions. Thresholds for clinically important changes in performance are available for several tests. In pulmonary arterial hypertension, the 6-min walk test (6MWT), peak oxygen uptake and ventilation/carbon dioxide output indices appear to be the variables most responsive to vasodilators. While bronchodilators do not always show clinically relevant effects in chronic obstructive pulmonary disease, high-intensity constant work-rate (endurance) tests (CWRET) are considerably more responsive than incremental exercise tests and 6MWTs. High-intensity CWRETs need to be standardised to reduce interindividual variability. Additional physiological information and responsiveness can be obtained from isotime measurements, particularly of inspiratory capacity and dyspnoea. Less evidence is available for the endurance shuttle walk test. Although the incremental shuttle walk test and 6MWT are reliable and less expensive than cardiopulmonary exercise testing, two repetitions are needed at baseline. All exercise tests are safe when recommended precautions are followed, with evidence suggesting that no test is safer than others.

Biological quality control for cardiopulmonary exercise testing in multicenter clinical trials

Background

Precision and accuracy assurance in cardiopulmonary exercise testing (CPET) facilitates multicenter clinical trials by maximizing statistical power and minimizing participant risk. Current guidelines recommend quality control that is largely based on precision at individual testing centers (minimizing test–retest variability). The aim of this study was to establish a multicenter biological quality control (BioQC) method that considers both precision and accuracy in CPET.

Methods

BioQC testing was 6-min treadmill walking at 20 W and 70 W (below the lactate threshold) with healthy non-smoking laboratory staff (15 centers; ~16 months). Measurements were made twice within the initial 4 weeks and quarterly thereafter. Quality control was based on: 1) within-center precision (coefficient of variation [CV] for oxygen uptake [V̇O₂], carbon dioxide output [V̇CO₂], and minute ventilation [V̇E] within ±10 %); and 2) a criterion that V̇O₂ at 20 W and 70 W, and ∆V̇O₂/∆WR were each within ±10 % predicted. “Failed” BioQC tests (i.e., those outside the predetermined criterion) prompted troubleshooting and repeated measurements. An additional retrospective analysis, using a composite z-score combining both BioQC precision and accuracy of V̇O₂ at 70 W and ∆V̇O₂/∆WR, was compared with the other methods.

Results

Of 129 tests (5 to 8 per center), 98 (76 %) were accepted by within-center precision alone. Within-center CV was <9 %, but between-center CV remained high (9.6 to 12.5 %). Only 43 (33 %) tests had all V̇O₂ measurements within the ±10 % predicted criterion. However, a composite z-score of 0.67 identified 67 (52 %) non-normal outlying tests, exclusion of which coincided with the minimum CV for CPET variables.

Conclusions

Study-wide BioQC using a composite z-score can increase study-wide precision and accuracy, and optimize the design and conduct of multicenter clinical trials involving CPET.

Trial registration

ClinicalTrials.gov identifier: NCT01072396; February 19, 2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0174-8) contains supplementary material, which is available to authorized users.

Pulmonary Rehabilitation: Improvement with Movement

This article serves as a CME- available, enduring material summary of the following COPD9_USA presentations: - "Lessons Learned from Pulmonary Education Program and On Track with COPD Ongoing Health Management." Presenter: Scott Cerreta, BS, RRT - "Cultivating Memorial Funds for Pulmonary Rehabilitation" Presenter: Valerie McLeod, RRT - "Strategies for Success: Maintenance Program Best Practices" Presenter: David Vines, MHS, RRT - "Strategies for Success-Maximizing Participation and Completion Rates," Presenter: Trina M. Limberg, BS, RRT.

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.

8th International conference on management and rehabilitation of chronic respiratory failure: the long summaries – Part 3

This paper summarizes the Part 3 of the proceedings of the 8^th International Conference on Management and Rehabilitation of Chronic Respiratory Failure, held in Pescara, Italy, on 7 and 8 May, 2015. It summarizes the contributions from numerous experts in the field of chronic respiratory disease and chronic respiratory failure. The outline follows the temporal sequence of presentations.

This paper (Part 3) presents a section regarding Moving Across the Spectrum of Care for Long-Term Ventilation (Moving Across the Spectrum of Care for Long-Term Ventilation, New Indications for Non-Invasive Ventilation, Elective Ventilation in Respiratory Failure - Can you Prevent ICU Care in Patients with COPD?, Weaning in Long-Term Acute Care Hospitals in the United States, The Difficult-to-Wean Patient: Comprehensive management, Telemonitoring in Ventilator-Dependent Patients, Ethics and Palliative Care in Critically-Ill Respiratory Patients, and Ethics and Palliative Care in Ventilator-Dependent Patients).

Effect of Megestrol Acetate and Testosterone on Body Composition and Hormonal Responses in COPD Cachexia

Background: Underweight chronic obstructive pulmonary disease (COPD) patients with involuntary weight loss have a poor prognosis; no effective therapy is currently available. We conducted the first clinical trial seeking to determine whether combination therapy with an appetite stimulant and an anabolic steroid would have beneficial effects on body composition for patients with COPD cachexia. Methods: We conducted a 12-week pilot study in which 4 men and 5 women (age 64±10 y, forced expiratory volume in 1 second [FEV₁] 31±9 %pred., body mass index [BMI] 18±3 kg/m²) with low-normal testosterone levels (average 532±45ng/dl in men and 12.4±5.3ng/dl in women) and weight loss ≥10 lbs over the previous year were treated with oral megestrol acetate 800mg/day plus weekly testosterone enanthate injections, initially 125 mg in men and 40 mg in women, with doses subsequently adjusted targeting circulating nadir testosterone levels of 850 and 300 ng/dl, respectively. Results: On treatment, nadir testosterone level increases averaged 160±250 ng/dl (NS) in men and 322±49 (p<0.001) ng/dl in women. Body weight increased in all individuals, with average end-intervention weight gain of 3.1±2.2 kg (p<0.005). Two women and 2 men had COPD exacerbations and did not complete the 12-week study. In the 5 individuals who completed, dual energy x ray absorptiometry (DEXA) scans revealed an average 2.0±1.5 kg lean mass and 2.3±1.7 kg fat mass increase (each p<0.05). No adverse effects of treatment were detected. Conclusions: Combination therapy reversed the trajectory of involuntary weight loss and increased lean mass in cachectic COPD patients. Though the interventions were apparently well tolerated, participant drop-out rate was high. Larger randomized placebo-controlled long-term studies with functional outcomes are needed.

8th International Conference on Management and Rehabilitation of Chronic Respiratory Failure: the Long Summaries

This paper summarizes Part 1 of the proceedings of the 8th International Conference on Management and Rehabilitation of Chronic Respiratory Failure, held in Pescara, Italy, on 7 and 8 May, 2015. It summarizes the contributions from numerous experts in the field of chronic respiratory disease and chronic respiratory failure. The outline follows the temporal sequence of presentations. This paper (Part 1) includes sections regarding: Advances in Asthma and COPD Therapy (Novel Therapeutic Targets for Asthma: Proteinases, Blood Biomarker Changes in COPD Patients); The problem of Hospital Re-Admission following Discharge after the COPD Exacerbation (Characteristics of the Hospitalized COPD Patient, Reducing Hospital Readmissions Following COPD Exacerbation). This paper summarizes Part 2 of the proceedings of the 8th International Conference on Management and Rehabilitation of Chronic Respiratory Failure, held in Pescara, Italy, on 7 and 8 May, 2015. It summarizes the contributions from numerous experts in the field of chronic respiratory disease and chronic respiratory failure. The outline follows the temporal sequence of presentations. This paper (Part 2) includes sections regarding: Promoting Physical Activity across the Spectrum of COPD (Physical activity: definitions, measurements, and significance; Increasing Physical Activity through Pharmacotherapy in COPD); Pulmonary Rehabilitation in Critical Illness (Complex COPD with comorbidities and its impact during acute exacerbation; Collaborative Self-Management in COPD: A Double-Edged Sword?; and Pulmonary Rehabilitation in Critical Illness. This paper summarizes Part 3 of the proceedings of the 8th International Conference on Management and Rehabilitation of Chronic Respiratory Failure, held in Pescara, Italy, on 7 and 8 May, 2015. It summarizes the contributions from numerous experts in the field of chronic respiratory disease and chronic respiratory failure. The outline follows the temporal sequence of presentations. This paper (Part 3) presents a section regarding Moving Across the Spectrum of Care for Long-Term Ventilation (Moving Across the Spectrum of Care for Long-Term Ventilation, New Indications for Non-Invasive Ventilation, Elective Ventilation in Respiratory Failure - Can you Prevent ICU Care in Patients with COPD?, Weaning in Long-Term Acute Care Hospitals in the United States, The Difficult-to-Wean Patient: Comprehensive management, Telemonitoring in Ventilator-Dependent Patients, Ethics and Palliative Care in Critically-Ill Respiratory Patients, and Ethics and Palliative Care in Ventilator-Dependent Patients).

8th international conference on management and rehabilitation of chronic respiratory failure: the long summaries – part 1

This paper summarizes the Part 1 of the proceedings of the 8^th International Conference on Management and Rehabilitation of Chronic Respiratory Failure, held in Pescara, Italy, on 7 and 8 May, 2015. It summarizes the contributions from numerous experts in the field of chronic respiratory disease and chronic respiratory failure. The outline follows the temporal sequence of presentations.

This paper (Part 1) includes sections regarding: Advances in Asthma and COPD Therapy (Novel Therapeutic Targets for Asthma: Proteinases, Blood Biomarker Changes in COPD Patients); The problem of Hospital Re-Admission following Discharge after the COPD Exacerbation (Characteristics of the Hospitalized COPD Patient, Reducing Hospital Readmissions Following COPD Exacerbation).

Effect of endurance and/or strength training on muscle fiber size, oxidative capacity, and capillarity in hemodialysis patients

We previously reported reduced limb muscle fiber succinate dehydrogenase (SDH) activity and capillarity density and increased cross-sectional areas (CSAs) of all fiber types in maintenance hemodialysis (MHD) patients compared with matched controls that may contribute to their effort intolerance and muscle weakness. This study evaluated whether endurance training (ET), strength training (ST), or their combination (EST) alters these metabolic and morphometric aberrations as a mechanism for functional improvement. Five groups were evaluated: 1) controls; 2) MHD/no training; 3) MHD/ET; 4) MHD/ST; and 5) MHD/EST. Training duration was 21.5 ± 0.7 wk. Vastus lateralis muscle biopsies were obtained after HD at baseline and at study end. Muscle fibers were classified immunohistochemically, and fiber CSAs were computed. Individual fiber SDH activity was determined by a microdensitometric assay. Capillaries were identified using antibodies against endothelial cells. Type I and IIA fiber CSAs decreased significantly (10%) with EST. In the ET group, SDH activity increased 16.3% in type IIA and 19.6% in type IIX fibers. Capillary density increased significantly by 28% in the EST group and 14.3% with ET. The number of capillaries surrounding individual fiber type increased significantly in EST and ET groups. Capillary-to-fiber ratio increased significantly by 11 and 9.6% in EST and ET groups, respectively. We conclude that increments in capillarity and possibly SDH activity in part underlie improvements in endurance of MHD patients posttraining. We speculate that improved specific force and/or neural adaptations to exercise underlie improvements in limb muscle strength of MHD patients.

Cluster Analysis in Patients with GOLD 1 Chronic Obstructive Pulmonary Disease

Background

We hypothesized that heterogeneity exists within the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 spirometric category and that different subgroups could be identified within this GOLD category.

Methods

Pre-randomization study participants from two clinical trials were symptomatic/asymptomatic GOLD 1 chronic obstructive pulmonary disease (COPD) patients and healthy controls. A hierarchical cluster analysis used pre-randomization demographics, symptom scores, lung function, peak exercise response and daily physical activity levels to derive population subgroups.

Results

Considerable heterogeneity existed for clinical variables among patients with GOLD 1 COPD. All parameters, except forced expiratory volume in 1 second (FEV₁)/forced vital capacity (FVC), had considerable overlap between GOLD 1 COPD and controls. Three-clusters were identified: cluster I (18 [15%] COPD patients; 105 [85%] controls); cluster II (45 [80%] COPD patients; 11 [20%] controls); and cluster III (22 [92%] COPD patients; 2 [8%] controls). Apart from reduced diffusion capacity and lower baseline dyspnea index versus controls, cluster I COPD patients had otherwise preserved lung volumes, exercise capacity and physical activity levels. Cluster II COPD patients had a higher smoking history and greater hyperinflation versus cluster I COPD patients. Cluster III COPD patients had reduced physical activity versus controls and clusters I and II COPD patients, and lower FEV₁/FVC versus clusters I and II COPD patients.

Conclusions

The results emphasize heterogeneity within GOLD 1 COPD, supporting an individualized therapeutic approach to patients.

Trial registration

www.clinicaltrials.gov. NCT01360788 and NCT01072396.

Re-Defining Lower Limit of Normal for FEV1/FEV6, FEV1/FVC, FEV3/FEV6 and FEV3/FVC to Improve Detection of Airway Obstruction

Background: Spirometric values of 5880 never-smoking black, Latin, and white men and women in the Third National Health and Nutrition Examination Survey (NHANES-3) reference population were reviewed. Good published equations for forced expiratory volume in 1 second (FEV₁) over forced expiratory volume in 6 seconds (FEV₆) and FEV₁over forced vital capacity (FVC) often significantly mis-identified the lower limit of normal (LLN) targets in both younger and older adults. To improve detection of smaller airways disease in adults, we wished to redefine the LLN for these ratios and develop new ones for forced expiratory volume in 3 seconds (FEV₃)/FEV₆ and FEV₃/FVC. Methods: In each of 6 ethnic/gender, never-smoking NHANES-3 groups, arranged sequentially by age from 20.0 to 79.9 years, the values of FEV₁/FEV₆, FEV₁/FVC, FEV₃/FEV₆, and FEV₃/FVC were placed in groups of 40 so that the actual lowest second (5%) ratios could be identified. The slopes and intercepts of the resulting 24 linear equations through these lowest 5% ratios were then each adjusted by multiple iterations to best identify equations which actually identified the lowest 5% in both younger and older adults. Results: In all never-smokers, the new equations were closer to the 5% LLN targets than were those of Hankinson for FEV₁/FEV₆ and FEV₁/FVC and Quanjer for FEV₁/FVC. In 3508 NHANES-3 current smokers, the FEV₃/FEV₆ and FEV₃/FVC identified significantly more values below LLN than the FEV₁/FEV₆ and FEV₁/FVC. Conclusion: New simple linear iterative equations for FEV₁/FEV₆, FEV_1/FVC, FEV₃/FEV₆, and FEV₃/FVC to identify LLN are offered. None require exponents or logarithms. The latter 2 detected more abnormalities in current-smokers and likely better identify small airways disease in adults.

Comorbidities of COPD have a major impact on clinical outcomes, particularly in African Americans

BACKGROUND

COPD patients have a great burden of comorbidity. However, it is not well established whether this is due to shared risk factors such as smoking, if they impact patients exercise capacity and quality of life, or whether there are racial disparities in their impact on COPD.

METHODS

We analyzed data from 10,192 current and ex-smokers with (cases) and without COPD (controls) from the COPDGene® cohort to establish risk for COPD comorbidities adjusted for pertinent covariates. In adjusted models, we examined comorbidities prevalence and impact in African-Americans (AA) and Non-Hispanic Whites (NHW).

RESULTS

Comorbidities are more common in COPD compared to those with normal spirometry (controls), and the risk persists after adjustments for covariates including pack-years smoked. After adjustment for confounders, eight conditions were independently associated with worse exercise capacity, quality of life and dyspnea. There were racial disparities in the impact of comorbidities on exercise capacity, dyspnea and quality of life, presence of osteoarthritis and gastroesophageal reflux disease having a greater negative impact on all three outcomes in AAs than NHWs (p<0.05 for all interaction terms).

CONCLUSIONS

Individuals with COPD have a higher risk for comorbidities than controls, an important finding shown for the first time comprehensively after accounting for confounders. Individual comorbidities are associated with worse exercise capacity, quality of life, and dyspnea, in African-Americans compared to non-Hispanic Whites.

Common genetic variants associated with resting oxygenation in chronic obstructive pulmonary disease

Hypoxemia is a major complication of chronic obstructive pulmonary disease (COPD) that correlates with disease prognosis. Identifying genetic variants associated with oxygenation may provide clues for deciphering the heterogeneity in prognosis among patients with COPD. However, previous genetic studies have been restricted to investigating COPD candidate genes for association with hypoxemia. To report results from the first genome-wide association study (GWAS) of resting oxygen saturation (as measured by pulse oximetry [Spo2]) in subjects with COPD, we performed a GWAS of Spo2 in two large, well characterized COPD populations: COPDGene, including both the non-Hispanic white (NHW) and African American (AA) groups, and Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE). We identified several suggestive loci (P < 1 × 10(-5)) associated with Spo2 in COPDGene in the NHW (n = 2810) and ECLIPSE (n = 1758) groups, and two loci on chromosomes 14 and 15 in the AA group (n = 820) from COPDGene achieving a level of genome-wide significance (P < 5 × 10(-8)). The chromosome 14 single-nucleotide polymorphism, rs6576132, located in an intergenic region, was nominally replicated (P < 0.05) in the NHW group from COPDGene. The chromosome 15 single-nucleotide polymorphisms were rare in subjects of European ancestry, so the results could not be replicated. The chromosome 15 region contains several genes, including TICRR and KIF7, and is proximal to RHCG (Rh family C glyocoprotein gene). We have identified two loci associated with resting oxygen saturation in AA subjects with COPD, and several suggestive regions in subjects of European descent with COPD. Our study highlights the importance of investigating the genetics of complex traits in different racial groups.

Instantaneous quantification of skeletal muscle activation, power production, and fatigue during cycle ergometry

A rapid switch from hyperbolic to isokinetic cycling allows the velocity-specific decline in maximal power to be measured, i.e., fatigue. We reasoned that, should the baseline relationship between isokinetic power (Piso) and electromyography (EMG) be reproducible, then contributions to fatigue may be isolated from 1) the decline in muscle activation (muscle activation fatigue); and 2) the decline in Piso at a given activation (muscle fatigue). We hypothesized that the EMG-Piso relationship is linear, velocity dependent, and reliable for instantaneous fatigue assessment at intolerance during and following whole body exercise. Healthy participants (n = 13) completed short (5 s) variable-effort isokinetic bouts at 50, 70, and 100 rpm to characterize baseline EMG-Piso. Repeated ramp incremental exercise tests were terminated with maximal isokinetic cycling (5 s) at 70 rpm. Individual baseline EMG-Piso relationships were linear (r(2) = 0.95 ± 0.04) and velocity dependent (analysis of covariance). Piso at intolerance (two legs, 335 ± 88 W) was ∼45% less than baseline [630 ± 156 W, confidence interval of the difference (CIDifference) 211, 380 W, P < 0.05]. Following intolerance, Piso recovered rapidly (F = 44.1; P < 0.05; η(2) = 0.79): power was reduced (P < 0.05) vs. baseline only at 0-min (CIDifference 80, 201 W) and 1-min recovery (CIDifference 13, 80 W). Activation fatigue and muscle fatigue (one leg) were 97 ± 55 and 60 ± 50 W, respectively. Mean bias ± limits of agreement for reproducibility were as follows: baseline Piso 1 ± 30 W; Piso at 0-min recovery 3 ± 35 W; and EMG at Piso 3 ± 14%. EMG power is linear, velocity dependent, and reproducible. Deviation from this relationship at the limit of tolerance can quantify the "activation" and "muscle" related components of fatigue during cycling.

An official European Respiratory Society statement on physical activity in COPD

This European Respiratory Society (ERS) statement provides a comprehensive overview on physical activity in patients with chronic obstructive pulmonary disease (COPD). A multidisciplinary Task Force of experts representing the ERS Scientific Group 01.02 "Rehabilitation and Chronic Care" determined the overall scope of this statement through consensus. Focused literature reviews were conducted in key topic areas and the final content of this Statement was agreed upon by all members. The current knowledge regarding physical activity in COPD is presented, including the definition of physical activity, the consequences of physical inactivity on lung function decline and COPD incidence, physical activity assessment, prevalence of physical inactivity in COPD, clinical correlates of physical activity, effects of physical inactivity on hospitalisations and mortality, and treatment strategies to improve physical activity in patients with COPD. This Task Force identified multiple major areas of research that need to be addressed further in the coming years. These include, but are not limited to, the disease-modifying potential of increased physical activity, and to further understand how improvements in exercise capacity, dyspnoea and self-efficacy following interventions may translate into increased physical activity. The Task Force recommends that this ERS statement should be reviewed periodically (e.g. every 5-8 years).

Improving early-stage diagnosis and management of COPD in primary care

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease, but it often remains undetected in its mild and moderate forms. Patients frequently remain undiagnosed and untreated until the disease has become severe and debilitating, greatly impacting their quality of life. Primary care physicians (PCPs) are most often the first point of contact, and therefore they are in the best position to identify patients at risk of COPD in the early stages. Consequently, they play a critical role in the management of the disease, particularly smoking cessation. One of the earliest symptoms is activity-related dyspnea and subsequent exercise intolerance, often compensated for by reduction in physical activity. This review addresses the approaches used to identify COPD in the primary care setting, including simple tools such as handheld spirometers and questionnaires. A recent study demonstrated that, compared with usual care, use of the COPD Population Screener questionnaire alone and in combination with the copd-6 handheld spirometer significantly improved the odds of referral of patients with suspected COPD for pulmonary function testing or to a pulmonologist. Identification of patients suspected of having the disease and differentiation of COPD from asthma are important in order that treatment can be initiated in the mild stages to slow or prevent disease progression and reduce the risk of exacerbations. The review also discusses the evidence to date on pharmacologic treatment using short-acting and long-acting anticholinergics and β2-agonists, and nonpharmacologic interventions, such as smoking cessation, pulmonary rehabilitation, and influenza and pneumococcal vaccination in patients with mild and moderate COPD.

Predictors of chronic obstructive pulmonary disease exacerbation reduction in response to daily azithromycin therapy

RATIONALE

Daily azithromycin decreases acute exacerbations of chronic obstructive pulmonary disease (AECOPD), but long-term side effects are unknown.

OBJECTIVES

To identify the types of exacerbations most likely to be reduced and clinical subgroups most likely to benefit from azithromycin, 250 mg daily, added to usual care.

METHODS

Enrollment criteria included irreversible airflow limitation and AECOPD requiring corticosteroids, emergency department visit, or hospitalization in the prior year or use of supplemental oxygen. Recurrent events and cumulative incidence analyses compared treatment received for AECOPD by randomization group, stratified by subgroups of interest. Cox proportional hazards models estimated treatment effects in subgroups adjusted for age, sex, smoking status, FEV1% predicted, concomitant COPD medications, and oxygen use.

MEASUREMENTS AND MAIN RESULTS

Azithromycin was most effective in reducing AECOPD requiring both antibiotic and steroid treatment (n = 1,113; cumulative incidence analysis, P = 0.0002; recurrent events analysis, P = 0.002). No difference in treatment response by sex (P = 0.75), presence of chronic bronchitis (P = 0.19), concomitant inhaled therapy (P = 0.29), or supplemental oxygen use (P = 0.23) was observed. Older age and milder Global Initiative for Chronic Obstructive Lung Disease stage were associated with better treatment response (P = 0.02 and 0.04, respectively). A significant interaction between treatment and current smoking was seen (P = 0.03) and azithromycin did not reduce exacerbations in current smokers (hazard ratio, 0.99; 95% confidence interval, 0.71-1.38; P = 0.95).

CONCLUSIONS

Azithromycin is most effective in preventing AECOPD requiring both antibiotic and steroid treatment. Adjusting for confounders, we saw no difference in efficacy by sex, history of chronic bronchitis, oxygen use, or concomitant COPD therapy. Greater efficacy was seen in older patients and milder Global Initiative for Chronic Obstructive Lung Disease stages. We found little evidence of treatment effect among current smokers. Clinical trial registered with www.clinicaltrials.gov (NCT0011986 and NCT00325897).

An official American Thoracic Society/European Respiratory Society statement: update on limb muscle dysfunction in chronic obstructive pulmonary disease

BACKGROUND

Limb muscle dysfunction is prevalent in chronic obstructive pulmonary disease (COPD) and it has important clinical implications, such as reduced exercise tolerance, quality of life, and even survival. Since the previous American Thoracic Society/European Respiratory Society (ATS/ERS) statement on limb muscle dysfunction, important progress has been made on the characterization of this problem and on our understanding of its pathophysiology and clinical implications.

PURPOSE

The purpose of this document is to update the 1999 ATS/ERS statement on limb muscle dysfunction in COPD.

METHODS

An interdisciplinary committee of experts from the ATS and ERS Pulmonary Rehabilitation and Clinical Problems assemblies determined that the scope of this document should be limited to limb muscles. Committee members conducted focused reviews of the literature on several topics. A librarian also performed a literature search. An ATS methodologist provided advice to the committee, ensuring that the methodological approach was consistent with ATS standards.

RESULTS

We identified important advances in our understanding of the extent and nature of the structural alterations in limb muscles in patients with COPD. Since the last update, landmark studies were published on the mechanisms of development of limb muscle dysfunction in COPD and on the treatment of this condition. We now have a better understanding of the clinical implications of limb muscle dysfunction. Although exercise training is the most potent intervention to address this condition, other therapies, such as neuromuscular electrical stimulation, are emerging. Assessment of limb muscle function can identify patients who are at increased risk of poor clinical outcomes, such as exercise intolerance and premature mortality.

CONCLUSIONS

Limb muscle dysfunction is a key systemic consequence of COPD. However, there are still important gaps in our knowledge about the mechanisms of development of this problem. Strategies for early detection and specific treatments for this condition are also needed.

Simvastatin for the prevention of exacerbations in moderate-to-severe COPD

BACKGROUND

Retrospective studies have shown that statins decrease the rate and severity of exacerbations, the rate of hospitalization, and mortality in chronic obstructive pulmonary disease (COPD). We prospectively studied the efficacy of simvastatin in preventing exacerbations in a large, multicenter, randomized trial.

METHODS

We designed the Prospective Randomized Placebo-Controlled Trial of Simvastatin in the Prevention of COPD Exacerbations (STATCOPE) as a randomized, controlled trial of simvastatin (at a daily dose of 40 mg) versus placebo, with annual exacerbation rates as the primary outcome. Patients were eligible if they were 40 to 80 years of age, had COPD (defined by a forced expiratory volume in 1 second [FEV1] of less than 80% and a ratio of FEV1 to forced vital capacity of less than 70%), and had a smoking history of 10 or more pack-years, were receiving supplemental oxygen or treatment with glucocorticoids or antibiotic agents, or had had an emergency department visit or hospitalization for COPD within the past year. Patients with diabetes or cardiovascular disease and those who were taking statins or who required statins on the basis of Adult Treatment Panel III criteria were excluded. Participants were treated from 12 to 36 months at 45 centers.

RESULTS

A total of 885 participants with COPD were enrolled for approximately 641 days; 44% of the patients were women. The patients had a mean (±SD) age of 62.2±8.4 years, an FEV1 that was 41.6±17.7% of the predicted value, and a smoking history of 50.6±27.4 pack-years. At the time of study closeout, the low-density lipoprotein cholesterol levels were lower in the simvastatin-treated patients than in those who received placebo. The mean number of exacerbations per person-year was similar in the simvastatin and placebo groups: 1.36±1.61 exacerbations and 1.39±1.73 exacerbations, respectively (P=0.54). The median number of days to the first exacerbation was also similar: 223 days (95% confidence interval [CI], 195 to 275) and 231 days (95% CI, 193 to 303), respectively (P=0.34). The number of nonfatal serious adverse events per person-year was similar, as well: 0.63 events with simvastatin and 0.62 events with placebo. There were 30 deaths in the placebo group and 28 in the simvastatin group (P=0.89).

CONCLUSIONS

Simvastatin at a daily dose of 40 mg did not affect exacerbation rates or the time to a first exacerbation in patients with COPD who were at high risk for exacerbations. (Funded by the National Heart, Lung, and Blood Institute and the Canadian Institutes of Health Research; STATCOPE ClinicalTrials.gov number, NCT01061671.).

The continuum of physiological impairment during treadmill walking in patients with mild-to-moderate COPD: patient characterization phase of a randomized clinical trial

BACKGROUND

To have a better understanding of the mechanisms of exercise limitation in mild-to-moderate chronic obstructive pulmonary disease (COPD), we compared detailed respiratory physiology in patients with COPD and healthy age- and sex-matched controls.

METHODS

Data were collected during the pre-treatment, patient characterization phase of a multicenter, randomized, double-blind, crossover study. Patients with COPD met Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 or 2 spirometric criteria, were symptomatic, and had evidence of gas trapping during exercise. All participants completed pulmonary function and symptom-limited incremental treadmill exercise tests.

RESULTS

Chronic activity-related dyspnea measured by Baseline Dyspnea Index was similarly increased in patients with GOLD 1 (n = 41) and 2 (n = 63) COPD compared with controls (n = 104). Plethysmographic lung volumes were increased and lung diffusing capacity was decreased in both GOLD groups. Peak oxygen uptake and work rate were reduced in both GOLD groups compared with controls (p<0.001). Submaximal ventilation, dyspnea, and leg discomfort ratings were higher for a given work rate in both GOLD groups compared with controls. Resting inspiratory capacity, peak ventilation, and tidal volume were reduced in patients with GOLD 2 COPD compared with patients with GOLD 1 COPD and controls (p<0.001).

CONCLUSIONS

Lower exercise tolerance in patients with GOLD 1 and 2 COPD compared with controls was explained by greater mechanical abnormalities, greater ventilatory requirements, and increased subjective discomfort. Lower resting inspiratory capacity in patients with GOLD 2 COPD was associated with greater mechanical constraints and lower peak ventilation compared with patients with GOLD 1 COPD and controls.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01072396.

The COPD Biomarker Qualification Consortium (CBQC)

Knowledge about the pathogenesis and pathophysiology of chronic obstructive pulmonary disease (COPD) has advanced dramatically over the last 30 years. Unfortunately, this has had little impact in terms of new treatments. Over the same time frame, only one new class of medication for COPD has been introduced. Even worse, the rate at which new treatments are being developed is slowing. The development of new tools for the assessment of new treatments has not kept pace with understanding of the disease. In part, this is because drug development tools require a regulatory review, and no interested party has been in a position to undertake such a process. In order to facilitate the development of novel tools to assess new treatments, the Food and Drug Administration, in collaboration with the COPD Foundation, the National Heart Lung and Blood Institute and scientists from the pharmaceutical industry and academia conducted a workshop to survey the available information that could contribute to new tools. Based on this, a collaborative project, the COPD Biomarkers Qualification Consortium, was initiated. The Consortium in now actively preparing integrated data sets from existing resources that can address the problem of drug development tools for COPD.

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.

Risk loci for chronic obstructive pulmonary disease: a genome-wide association study and meta-analysis

BACKGROUND

The genetic risk factors for susceptibility to chronic obstructive pulmonary disease (COPD) are still largely unknown. Additional genetic variants are likely to be identified by genome-wide association studies in larger cohorts or specific subgroups. We sought to identify risk loci for moderate to severe and severe COPD with data from several cohort studies.

METHODS

We combined genome-wide association analysis data from participants in the COPDGene study (non-Hispanic white and African-American ethnic origin) and the ECLIPSE, NETT/NAS, and Norway GenKOLS studies (self-described white ethnic origin). We did analyses comparing control individuals with individuals with moderate to severe COPD and with a subset of individuals with severe COPD. Single nucleotide polymorphisms yielding a p value of less than 5 × 10(-7) in the meta-analysis at loci not previously described were genotyped in individuals from the family-based ICGN study. We combined results in a joint meta-analysis (threshold for significance p<5 × 10(-8)).

FINDINGS

Analysis of 6633 individuals with moderate to severe COPD and 5704 control individuals confirmed association at three known loci: CHRNA3 (p=6·38 × 10(-14)), FAM13A (p=1·12 × 10(-14)), and HHIP (p=1·57 × 10(-12)). We also showed significant evidence of association at a novel locus near RIN3 (p=5·25 × 10(-9)). In the overall meta-analysis (ie, including data from 2859 ICGN participants), the association with RIN3 remained significant (p=5·4 × 10(-9)). 3497 individuals were included in our analysis of severe COPD. The effect estimates for the loci near HHIP and CHRNA3 were significantly stronger in severe disease than in moderate to severe disease (p<0·01). We also identified associations at two additional loci: MMP12 (overall joint meta-analysis p=2·6 × 10(-9)) and TGFB2 (overall joint meta-analysis p=8·3 × 10(-9)).

INTERPRETATION

We have confirmed associations with COPD at three known loci and identified three new genome-wide significant associations. Genetic variants other than in α-1 antitrypsin increase the risk of COPD.

FUNDING

US National Heart, Lung, and Blood Institute; the Alpha-1 Foundation; the COPD Foundation through contributions from AstraZeneca, Boehringer Ingelheim, Novartis, and Sepracor; GlaxoSmithKline; Centers for Medicare and Medicaid Services; Agency for Healthcare Research and Quality; and US Department of Veterans Affairs.