The 6-Minute-Walk Distance Test as a Chronic Obstructive Pulmonary Disease Stratification Tool. Insights from the COPD Biomarker Qualification Consortium

Segmental phase angle can predict incidence of severe exacerbation in male patients with COPD

OBJECTIVE

To investigate whether segmental phase angle (PhA) is a useful predictor of severe chronic obstructive pulmonary disease (COPD) exacerbation.

RESEARCH METHODS AND PROCEDURES

This prospective cohort study enrolled consecutive patients with COPD with a follow-up period of 3 years. The primary outcome was incidence of severe exacerbation. PhA was measured for the whole body and segmental body sites (trunk and upper and lower limbs). We used receiver operating characteristic (ROC) curves to determine the cut-off values and area under the curve (AUC) for predicting exacerbation based on PhA. We applied Cox proportional hazard regression analyses to estimate the independent prognostic effect of PhA on the incidence of severe exacerbation.

RESULTS

We analyzed 108 male participants (mean age 75.1±7.9 years) and the median follow-up period was 1082 [643-1103] days, with an annual severe exacerbation incidence rate of 0.23 per person-year. ROC analysis revealed that the AUC for Whole-body and segmental PhA were as follows: Whole-body: AUC = 0.69 (95% confidence interval [CI] = 0.59-0.79); right arm: AUC = 0.65 (95% CI = 0.53-0.77); left arm: AUC = 0.68 (95% CI = 0.56-0.79); right leg: AUC = 0.73 (95% CI = 0.64-0.82); left leg: AUC = 0.71 (95% CI = 0.62-0.81); trunk: AUC = 0.58 (95% CI = 0.46-0.69). Cox proportional hazard analysis demonstrated that PhA of the right leg (hazard ratio [HR]=3.50, 95% CI=1.33-9.20), left leg (HR=3.26, 95% CI=1.18-9.04), and left arm (HR=2.61, 95% CI=1.17-6.80) were independently and significantly associated with incidence of severe exacerbation. Whole and trunk PhA were not significantly associated with the incidence of severe exacerbation.

CONCLUSIONS

Segmental PhA may serve as a valuable predictive indicator of severe exacerbation in male patients with COPD. Notably, both leg PhA were strongly associated with the occurrence of severe exacerbations.

REGISTRY NUMBER

UMIN000044824.

The effect of torque teno virus (TTV) infection on clinical outcomes, genomic integrity, and mortality in COPD patients

INTRODUCTION

Torque Teno Virus (TTV), an "orphan" virus with unclear pathology, has been associated with various diseases and immune dysfunctions. This study investigates the link between TTV viremia and clinical markers in patients with severe to very severe COPD undergoing respiratory rehabilitation.

METHODS

We analyzed 102 elderly COPD patients, stratified by TTV viremia levels (< or ≥ 4 log10 copies/mL). Clinical markers-including mortality, inflammatory-oxidative parameters (Lymphocyte/Monocyte, Neutrophil/Lymphocyte, and Platelet/Lymphocyte ratios), IL-6 (measured via ELISA assay), and DNA damage (assessed via comet assay)-were evaluated.

RESULTS

Of the patients, 62.75 % had TTV viremia levels > 4 log10 copies/mL. No associations were found between TTV levels and sex or obesity. However, higher TTV viremia correlated with increased DNA damage and significantly lower 5-year survival probability.

CONCLUSION

Patients with TTV levels ≥ 4 log10 copies/mL exhibited the lowest survival probability, though DNA damage emerged as a stronger determinant of outcomes. This study raises key scientific questions on the role of TTV in COPD. Specifically, it explores whether TTV may serve as a potential marker for poor prognosis in COPD and whether rehabilitation strategies for these patients could be customized based on DNA damage and/or viremia.

Functional capacity, quality of life, and disability in fibrosing interstitial lung disease: Insights into pulmonary function and outcomes

OBJECTIVE

This study aimed to evaluate lung function, functional capacity, quality of life, functionality, and disability in individuals diagnosed with Fibrosing Interstitial Lung Disease (IFLD).

METHODS

The research employed a cross-sectional design and included participants with a confirmed diagnosis of IFLD. Variables under investigation included: 1. Sociodemographic factors; 2. Pulmonary Function; 3. Functional Capacity; 4. Quality of life; 5. Functioning and Disability assessed using the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0). Ethical approval for the study was obtained from the Research Ethics Committee of the State University of Bahia (UNEB).

RESULTS

The predicted and observed distances in the six-minute walk test were 545.9±45.2 and 414.5±140.3 meters, respectively. Patients classified with a modified dyspnea scale (mMRC)=4 exhibited a significantly greater impact on functionality. The WHODAS 2.0 domains of social participation and activities of daily living were most affected in IFLD patients. Statistically significant associations were found between the distance covered and WHODAS - locomotion (r=-0.46; p<0.001) as well as between the distance covered and WHODAS-self-care (r=-0.51; p<0.001). In terms of quality of life, mental health and vitality emerged as the most compromised domains.

CONCLUSION

This study revealed a decline in lung function, functional capacity, quality of life, and overall functionality among individuals with IFLD. Notably, the most substantial impairments were identified in domains directly related to quality of life and social interaction.

Comparing penetrating needles and non-penetrating needles with electrical stimulation combined with exercise training for relief of dyspnea and improving exercise tolerance in chronic obstructive pulmonary disease patients: A single-blind randomized controlled trial

Background

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation. The purpose of this study was to evaluate the effectiveness of penetrating needles with electrical stimulation combined with exercise training on relieving dyspnea and improving exercise tolerance among COPD patients.

Method

A total of 85 patients were recruited and randomly assigned to receive either penetrating needles with electrical stimulation (PE) or non-penetrating needles with electrical stimulation (NPE), 3 times a week, for 8 weeks, totaling 24 treatments. Both groups underwent exercise training. The evaluations were conducted at the baseline, after 14 treatments, and after 24 treatments.

Results

The PE group showed significant improvement in 6-minute walk distance (6MWD) after the 14th treatment. For pulmonary function test, MVV%, MEF50%, MEF75% and MEF25% improved in the PE group, especially MVV% was significantly higher than the NPE group. For cardiopulmonary exercise testing, METs%, VO2/kg%, VE%, VO2/HR%, VEmax, VE/VO2 and VE/VCO2 in the PE group improved, especially VO2/kg%, VE%, VEmax, VE/VO2 and VE/VCO2 were significantly higher than the NPE group. The scores of COPD assessment test in the PE group significantly improved. The scores of modified British Medical Research Council in the PE group was better than the NPE group after the treatment.

Conclusion

Penetrating needles with electrical stimulation combined with exercise training may be clinically useful for COPD patients in relieving dyspnea and improving exercise tolerance.

Trial Registration

Chinese Clinical Trial Registry, ChiCTR1900028627.

Serum Soluble Urokinase-Type Plasminogen Activator Receptor: A Promising Biomarker for Stable Chronic Obstructive Pulmonary Disease Patients

Background Chronic obstructive pulmonary disease (COPD) is a condition in which airflow limitation becomes irreversible over time, often resulting from long-term exposure to environmental pollutants, harmful particles, smoke, and biomass fuel. Beyond FEV1, identifying a more specific biomarker to predict COPD progression remains a challenge. Soluble urokinase-type plasminogen activator receptor (suPAR) expression increases in the respiratory epithelial cells of COPD patients. This study aimed to evaluate serum suPAR levels across different grades of stable COPD patients. Methods Two hundred stable COPD patients (148 males and 52 females) were recruited after obtaining informed consent. Blood samples were collected, and serum suPAR levels were measured in all participants. Results Serum suPAR levels were elevated in COPD patients at Global Initiative for Obstructive Lung Disease (GOLD) stages IV and III (6.38 ± 0.05 ng/ml and 5.82 ± 0.18 ng/ml, respectively) compared to those at GOLD stages II and I (5.15 ± 0.25 ng/ml and 4.17 ± 0.29 ng/ml). A one-way ANOVA confirmed that the differences between groups were statistically significant (F = 428.83, p < 0.001). Conclusions This study suggests that serum suPAR levels can serve as a diagnostic marker for COPD. As low-grade pulmonary inflammation increases with disease severity, suPAR levels also rise. Additionally, this marker may be useful for monitoring the prognosis of stable COPD and assessing treatment response.

Reproducibility of three 6-min walk tests in patients with COPD referred for pulmonary rehabilitation

INTRODUCTION AND OBJECTIVES

The 6-min walk test (6MWT) is used to assess functional capacity in patients with COPD. A significant number of studies have shown that most patients walk further in a second 6MWT. Research on a further increase in the 6-min walk distance (6MWD) during a 3rd test performed in accordance with current guidelines has not been done. Therefore, this study aimed to investigate 1) the reproducibility of three 6MWTs in patients with COPD referred for pulmonary rehabilitation (PR) and 2) predictors of improvement on a third 6MWT.

MATERIALS AND METHODS

Before the start of PR, 1167 COPD patients (50 % male, age: 62 ± 9 years; FEV1: 42 ± 18%pred) performed three 6MWTs (6MWT1, 6MWT2, and 6MWT3). A predetermined threshold of ≥42m improvement in 6MWD in consecutive 6MWT's was used to identify improvers. Reproducibility between tests was assessed using a Bland-Altman plot and logistic regression analyses were performed to assess effects of sex, age, body mass index, GOLD-stage, 6MWD, use of supplemental oxygen and use of walking aids.

RESULTS

Generally, the 6MWD improved (6MWT1: 343 ± 115m; 6MWT2: 367 ± 115m; 6MWT3: 381 ± 116m). 210 patients (18 %) improved ≥42m from 6MWT2 to 6MWT3. The Bland-Altman plot showed that the 95 % limits of agreement of 6MWT3 vs 6MWT2 exceeded 42m, indicating that 6MWT2 is not reproducible. Predictors of improvement in 6MWT3 were GOLD stage I/II and a low 6MWD (<350m) in the previous two 6MWTs.

CONCLUSIONS

These results indicate that three 6MWTs may be required to obtain the largest pre-PR functional capacity in COPD patients. Patients with a 6MWD <350m and GOLD-stage I/II are more likely to improve ≥42m in a third 6MWT.

The Responsiveness of Exercise Tests in COPD: A Randomized Controlled Trial

BACKGROUND

COPD is characterized by reduced exercise tolerance, and improving physical performance is an important therapeutic goal. A variety of exercise tests are commonly used to assess exercise tolerance, including laboratory and field-based tests. The responsiveness of these various tests to common COPD interventions is yet to be compared, but the results may inform test selection in clinical and research settings.

RESEARCH QUESTION

What exercise test possesses the greatest sensitivity to change from before to after intervention in patients with COPD?

STUDY DESIGN AND METHODS

One hundred fifty-four patients with symptomatic COPD were recruited and randomized (2:1:1) to 6 weeks of long-acting muscarinic antagonist, pulmonary rehabilitation (PR), or usual care. Before and after intervention, participants performed an incremental cycle exercise test and constant work rate cycle test (CWRCT), incremental shuttle walk test and endurance shuttle walk test (ESWT), 6-min walk test, and 4-m gait speed test.

RESULTS

One hundred three participants (mean ± SD age, 67 ± 8 years; 75 male participants [73%]; FEV1, 50.6 ± 16.8% predicted) completed the study. Significant improvements in the incremental cycle exercise test, CWRCT, incremental cycle exercise test, ESWT, and 6-min walk test results were observed after PR (P < .05), with the greatest improvements seen in the constant work rate protocols (percentages change: CWRCT, 42%; ESWT, 41%).

INTERPRETATION

The ESWT and CWRCT seemed to be the most responsive exercise test protocols to long-acting muscarinic antagonist and PR therapy. The magnitude of change was much greater after a program of rehabilitation compared with bronchodilator therapy.

CLINICAL TRIAL REGISTRY

International Standard Randomised Controlled Trial Number (ISRCTN): No. 64759523; URL: https://www.isrctn.com/ISRCTN64759523.

Clinical improvements after endoscopic lung volume reduction with valves in patients with advanced emphysema and a 6-min walk test ≤140 m at baseline

Background

Data regarding the effectiveness and safety of endoscopic lung volume reduction with valves (ELVR) in emphysema patients with a very low 6-min walk test (6MWT) are limited. Patients with severe emphysema and very low exercise capacity, as indicated by a 6MWT ≤140 m, are often excluded from clinical studies on ELVR, assuming limited therapeutic benefits and increased complication risk.

Study designs and methods

This study utilised data from the Lungenemphysemregister e.V., a large German national multi-centre prospective open-label clinical trial, and aimed to assess the outcomes of ELVR in patients with a baseline 6MWT ≤140 m and dyspnoea primarily attributed to hyperinflation.

Results

54 patients with a baseline 6MWT ≤140 m and 365 patients with a baseline 6MWT between 140 and 450 m were included in the study. Baseline characteristics were representative for patients with advanced lung emphysema. Patients with a 6MWT ≤140 m at baseline had a lower forced expiratory volume in 1 s and diffusing capacity of the lung for carbon monoxide and higher symptom burden. In the 3-month follow-up, patients of both groups showed statistically significant improvements in lung function parameters, exercise capacity and quality of life parameters compared to baseline. Patients with a 6MWT ≤140 m at baseline showed significantly more 6MWT improvement compared to patients with baseline 6MWT between 140 and 450 m. Moreover, complication rates were similar in both groups.

Interpretation

In summary, the data indicate that ELVR may be an effective and safe treatment for emphysema patients with a very low 6MWT of ≤140 m if very limited exercise capacity is predominately caused by lung emphysema. Therefore future studies should include emphysema patients with a very low 6MWT.

The usefulness of Charlson Comorbidity Index (CCI) scoring in predicting all-cause mortality in Outpatients with Clinical Diagnoses of COPD

Background

Since comorbid conditions are frequently present in chronic obstructive pulmonary disease (COPD) and affect outcome, a composite scoring system to quantify comorbidity might be helpful in assessing mortality risk.

Methods

We tested the hypothesis that the Charlson Comorbidity Index (CCI) score at the time of an outpatient medical clinic encounter for COPD predicts all-cause mortality. Cox Proportional Hazards analyses were used in 200 randomly selected patients to relate CCI scores to all-cause mortality out to 5 years.

Results

Mean age was 62 ± 10 years, 56% were female, FEV1 was 62%, CCI was 3.08 ± 2.30, and 30% had a CCI ≥ 4, indicating 3 or more comorbid conditions. All-cause mortality was 8.5% and 20% at 3 and 5 years, respectively. In univariate testing, the CCI score and hospitalizations predicted mortality, but FEV1 did not. In multivariable testing, which included covariates of age, sex, socioeconomic status, race, FEV1 percent-predicted, and all-cause hospitalizations in the preceding year, CCI expressed as a continuous variable strongly predicted mortality: hazard ratio (HR) 1.38 for each unit increase in the score (p < 0.0001). While 1 or 2 comorbid conditions were not significantly related to mortality, 3 or more comorbid conditions (compared to none) strongly predicted mortality: HR 9.80, 95% CI 3.80 to 25.00.

Conclusion

Comorbidity, assessed with the CCI, is strongly predictive of mortality in outpatients with a clinical diagnosis of COPD, and this relationship appears to be non-linear. This instrument may be useful in determining prognosis in this population.

Long-term impact of Diabetes Prevention Program interventions on walking endurance

Objectives

Type 2 diabetes (T2D) and prediabetes are associated with poor walking endurance, a marker of physical function. We aimed to examine the long-term effects of metformin or intensive lifestyle intervention in adults at high risk of T2D on their 6-min walk test (6MWT) performance.

Methods

Participants were randomized in the 3-year Diabetes Prevention Program (DPP) to one of the three groups: lifestyle intervention, metformin, or placebo, and were subsequently followed in the DPP Outcomes Study. A 6MWT was conducted 20 years after randomization. Associations between DPP interventions and 6MWT completion (achieving a distance ≥200 m) were assessed using logistic regression. Among the test completers, differences in distance walked (6MWD) were evaluated using multivariable linear regression. Additional variables of interest included concomitant measures of body mass index (BMI) and grip strength along with mean measures of HbA1c and self-reported physical activity (PA).

Results

Data on 1830 participants were analyzed. The interventions were not associated with test completion or the 6MWD among test completers (362, 364, and 360 m in the lifestyle, metformin, and placebo groups, respectively, p = 0.8). Age, education, grip strength, and PA were each significantly associated with the 6MWT completion and the 6MWD after adjustment. Grip strength, PA, and education were positively associated with the 6MWD, while age, BMI, and HbA1c were negatively associated with the 6MWD.

Conclusion

We confirmed that the 6MWT is related to other measures of physical ability such as PA and grip strength in persons at risk for and with T2D, suggesting potential long-term benefits of maintaining a healthy lifestyle. However, we did not observe a sustained effect of the original randomized interventions.

Clinical trial registration

http://www.clinicaltrials.gov/ct/show/NCT00004992, identifier DPP NCT00004992; http://www.clinicaltrials.gov/ct/show/NCT00038727, identifier DPPOS NCT00038727.

Multifaceted associations between walking performance, physical fitness, extremity function, health status, and depression in individuals with COPD

BACKGROUND/OBJECTIVE(S)

Chronic obstructive pulmonary disease (COPD) can precipitate a deterioration of an individual's physical performance and overall health. Evidence suggests that, along with pulmonary functions, several other factors are related to the significant impairment of walking performance in individuals with COPD. This study compared the depressive symptoms, health status, upper and lower extremity functions, and peak oxygen uptake (VO2peak) in a group of individuals with COPD based on walking performance using a cutoff distance of 350 m in the six-minute walking test (6MWT). The study also investigated the associations between these factors and walking performance.

MATERIALS AND METHODS

Participants performed the 6MWT according to the guidelines and were classified into high (>350 m; n = 40) or low (<350 m; n = 30) walking performance groups according to distance. The forced expiratory volume (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio were recorded. Participants completed the Patient Health Questionnaire-9 (PHQ-9), St. George's Respiratory Questionnaire (SGRQ), and the Upper and Lower Extremity Functional Index (UEFI/LEFI). Predicted VO2peak was measured using the Duke Activity Status Index (DASI).

RESULTS

Seventy participants with a mean age of 63 ± 11 years (20% female) were enrolled in this study. Patients with high walking performance demonstrated significantly better health status than those with low walking performance (SGRQ: 49 ± 25 vs. 56 ± 21, p = 0.03). Participants with low walking performance had lower predicted VO2peak compared to their higher performing counterparts (p = 0.002). The overall model was significant (F(8, 61) = 7.48, p = 0.0006), with PHQ-9, SGRQ, UEFI/LEFI, VO2peak, and FEV1/FVC explaining approximately 49.5% of the variance in the 6MWT distance.

CONCLUSION

This study shed light on the association of depressive symptoms, health status, extremity function, and VO2peak with walking performance, providing valuable insights that may impact the management and care of individuals with COPD.

Percent Predicted vs. Absolute Six-Minute Walk Distance as Predictors of Lung Transplant-Free Survival in Fibrosing Interstitial Lung Diseases

INTRODUCTION

Fibrosing interstitial lung diseases (ILDs) often progress despite treatment and become life-threatening, with lung transplant (LTx) remaining the only curative option. Six-minute walk distance (6MWD) is increasingly recognized as reliable predictor of clinical course, especially when longitudinally considered. The use of reference equations to express 6MWD as percent predicted (6MWD%) has not been previously studied in fibrosing ILDs. We sought to investigate whether the prognostic power of 6MWD% is superior to that of 6MWD expressed in meters (6MWD-m).

METHODS

A retrospective, multicenter cohort analysis was conducted on both idiopathic pulmonary (IPF) and non-IPF fibrosing ILD patients. Patients were divided into a discovery (n = 211) and a validation (n = 260) cohort. Longitudinal changes of 6MWD% and lung function parameters were simultaneously considered. LTx-free survival at 3 years from baseline was the endpoint. Competing risks of death and LTx were considered.

RESULTS

Baseline 6MWD% and its longitudinal changes were significant predictors of LTx-free survival and independent from lung function variables. In both cohorts, on multivariate cox proportional hazard regression analysis, receiver operating characteristics analysis and Kaplan-Meier estimates, 6MWD% was consistently, but only slightly superior to 6MWD-m as a predictor of LTx-free survival.

CONCLUSION

6MWD% has only a slight, yet detectable advantage over 6MWD-m as a predictor of survival in fibrosing ILDs. Utilizing 6MWD% may aid in risk stratification, treatment monitoring, and LTx timing optimization. However, available reference equations do have predicting limitations. Refined predictive equations and standardizing reporting practices are therefore needed to further enhance the clinical utility of 6MWD% in fibrosing ILDs.

A protein risk score for all-cause and respiratory-specific mortality in non-Hispanic white and African American individuals who smoke

Protein biomarkers are associated with mortality in cardiovascular disease, but their effect on predicting respiratory and all-cause mortality is not clear. We tested whether a protein risk score (protRS) can improve prediction of all-cause mortality over clinical risk factors in smokers. We utilized smoking-enriched (COPDGene, LSC, SPIROMICS) and general population-based (MESA) cohorts with SomaScan proteomic and mortality data. We split COPDGene into training and testing sets (50:50) and developed a protRS based on respiratory mortality effect size and parsimony. We tested multivariable associations of the protRS with all-cause, respiratory, and cardiovascular mortality, and performed meta-analysis, area-under-the-curve (AUC), and network analyses. We included 2232 participants. In COPDGene, a penalized regression-based protRS was most highly associated with respiratory mortality (OR 9.2) and parsimonious (15 proteins). This protRS was associated with all-cause mortality (random effects HR 1.79 [95% CI 1.31-2.43]). Adding the protRS to clinical covariates improved all-cause mortality prediction in COPDGene (AUC 0.87 vs 0.82) and SPIROMICS (0.74 vs 0.6), but not in LSC and MESA. Protein-protein interaction network analyses implicate cytokine signaling, innate immune responses, and extracellular matrix turnover. A blood-based protein risk score predicts all-cause and respiratory mortality, identifies potential drivers of mortality, and demonstrates heterogeneity in effects amongst cohorts.

Nocturnal Hypoxemia Is Associated with Sarcopenia in Patients with Chronic Obstructive Pulmonary Disease

Rationale: Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. Our previous studies have identified that nocturnal hypoxemia causes skeletal muscle loss (i.e., sarcopenia) in in vitro models of COPD. Objectives: We aimed to extend our preclinical mechanistic findings by analyzing a large sleep registry to determine whether nocturnal hypoxemia is associated with sarcopenia in patients with COPD. Methods: Sleep studies from patients with COPD (n = 479) and control subjects without COPD (n = 275) were analyzed. Patients with obstructive sleep apnea, as defined by apnea-hypopnea index ⩾ 5, were excluded. Pectoralis muscle cross-sectional area (PMcsa) was quantified using computed tomography scans performed within 1 year of the sleep study. We defined sarcopenia as less than the lowest 20% residuals for PMcsa of control subjects, which was adjusted for age and body mass index (BMI) and stratified by sex. Youden's optimal cut-point criteria were used to predict sarcopenia based on mean oxygen saturation during sleep. Additional measures of nocturnal hypoxemia were analyzed. The pectoralis muscle index (PMI) was defined as PMcsa normalized to BMI. Results: On average, males with COPD had a 16.6% lower PMI than control males (1.41 ± 0.44 vs. 1.69 ± 0.56 cm2/BMI; P < 0.001), whereas females with COPD had a 9.4% lower PMI than control females (0.96 ± 0.27 vs. 1.06 ± 0.33 cm2/BMI; P < 0.001). Males with COPD with nocturnal hypoxemia had a 9.5% decrease in PMI versus COPD with normal O2 (1.33 ± 0.39 vs. 1.47 ± 0.46 cm2/BMI; P < 0.05) and a 23.6% decrease compared with control subjects (1.33 ± 0.39 vs. 1.74 ± 0.56 cm2/BMI; P < 0.001). Females with COPD with nocturnal hypoxemia had an 11.2% decrease versus COPD with normal O2 (0.87 ± 0.26 vs. 0.98 ± 0.28 cm2/BMI; P < 0.05) and a 17.9% decrease compared with control subjects (0.87 ± 0.26 vs. 1.06 ± 0.33 cm2/BMI; P < 0.001). These findings were largely replicated using multiple measures of nocturnal hypoxemia. Conclusions: We defined sarcopenia in the pectoralis muscle using residuals that take into account age, BMI, and sex. We found that patients with COPD have a lower PMI than patients without COPD and that nocturnal hypoxemia was associated with an additional decrease in the PMI of patients with COPD. Additional prospective analyses are needed to determine a protective threshold of oxygen saturation to prevent or reverse sarcopenia due to nocturnal hypoxemia in COPD.

Effect of Macronutrients or Micronutrients Supplementation on Nutritional Status, Physical Functional Capacity and Quality of Life in Patients with COPD: A Systematic Review and Meta-Analysis

Given the importance that a correct and balanced nutrition has on patients with chronic obstructive pulmonary disease (COPD), supplementation of macro and micronutrients has been proposed, but the results of previous meta-analyses are contrasting. We performed an update of the latest evidence through a systematic review and meta-analysis of studies to assess the role of nutritional supplements in improving nutritional status, pulmonary function, physical performance, and quality of life of these patients.We included randomized controlled trials (RCTs) published between 01-01-2010 and 11-01-2023 evaluating the effectiveness of nutritional support in patients affected by stable COPD with an intervention of at least 2 weeks. Primary outcomes were changes in body mass index (BMI) and fat free mass index (FFMI). Secondary outcomes were exercise tolerance (6-min walking test, 6MWT), quality of life (St George's Respiratory Questionnaire, SGRQ) and respiratory function (FEV1). According with supplements type (macronutrients or micronutrients), we calculated the pooled adjusted mean difference (MD) and 95% confidence intervals (95%CIs) of the selected outcomes, using random-effects models in presence of high heterogeneity (I2>50%) or fixed-effects models otherwise. The risk of publication bias was evaluated with the trim and fill method.From 967 articles, 20 RCTs were included. Macronutrients supplementation improved BMI (MD 1.0 kg/m2, 95%CI 0.21-1.79), FFMI (MD 0.77 Kg/m2, 95%CI 0.48-1.06), 6MQT (MD 68.39 m, 95%CI 40.07-96.71), and SGRQ (MD -5.14, 95% CI -7.31-2.97), while it does not ameliorate respiratory function (MD 0.26% 95%CI -1.87-2.40). Micronutrients supplementation alone did not improve any of the considered outcomes.

Prevalence and prognostic importance of exercise limitation and physical inactivity in COPD

Exercise limitation and physical inactivity are separate, but related constructs. Both are commonly present in individuals with COPD, contribute to disease burden over and above the respiratory impairments, and are independently predictive of adverse outcomes. Because of this, clinicians should consider assessing these variables in their patients with COPD. Field tests of exercise performance such as the 6-min walk test and the incremental and endurance shuttle walk tests require limited additional resources, and results correlate with negative outcomes. Laboratory measures of exercise performance using a treadmill or cycle ergometer assess exercise capacity, provide prognostic information and have the advantage of explaining physiological mechanisms (and their interactions) underpinning exercise limitation. Limitations in exercise capacity (i.e. "cannot do") and physical inactivity (i.e. "do not do") are both associated with mortality; exercise limitation appears to be the more important driver of this outcome.

Respiratory muscle strength can improve the prognostic assessment in COPD

Impaired lung function, respiratory muscle weakness and exercise intolerance are present in COPD and contribute to poor prognosis. However, the contribution of the combination of these manifestations to define prognosis in COPD is still unknown. This study aimed to define cut-off points for both inspiratory and expiratory muscle strength (MIP and MEP, respectively) for mortality prediction over 42-months in patients with COPD, and to investigate its combination with other noninvasive established prognostic measures (FEV1, V̇O2peak and 6MWD) to improve risk identification. Patients with COPD performed pulmonary function, respiratory muscle strength, six-minute walk and cardiopulmonary exercise tests, and were followed over 42 months to analyze all-cause mortality. A total of 79 patients were included. The sample was mostly (91.1%) comprised of severe (n = 37) and very severe (n = 34) COPD, and 43 (54%) patients died during the follow-up period. Cut-points of ≤ 55 and ≤ 80 cmH2O for MIP and MEP, respectively, were associated with increased risk of death (log-rank p = 0.0001 for both MIP and MEP) in 42 months. Furthermore, MIP and MEP substantially improved the mortality risk assessment when combined with FEV1 (log-ranks p = 0.006 for MIP and p < 0.001 for MEP), V̇O2peak (log-rank: p < 0.001 for both MIP and MEP) and 6MWD (log-ranks: p = 0.005 for MIP; p = 0.015 for MEP). Thus, patients severely affected by COPD presenting MIP ≤ 55 and/or MEP ≤ 80 cmH2O are at increased risk of mortality. Furthermore, MIP and MEP substantially improve the mortality risk assessment when combined with FEV1, V̇O2peak and 6MWD in patients with COPD.

Point: Center-Based Pulmonary Rehabilitation Is the Standard

Currently, a major pulmonary rehabilitation focus is on expanding access. At-home rehabilitation is being explored as an in-center pulmonary rehabilitation alternative. It has been asserted that in-home pulmonary rehabilitation confers similar benefits to in-center pulmonary rehabilitation. An extensive database documents that in-center pulmonary rehabilitation confers a range of patient-relevant benefits. Recently, evidence has been presented that in-center pulmonary rehabilitation improves survival, perhaps the most important benefit of all. It can be argued that improvements in physical fitness, assessed as exercise capacity, are mechanistically related to survival improvements. Therefore, in-home rehabilitation must demonstrate exercise capacity improvements similar to those regularly seen in-center to be considered equivalent. A literature search identified 11 studies that compared in-home with in-center pulmonary rehabilitation for COPD that recorded exercise tolerance outcomes. Despite being described as in-home programs, almost all featured prefatory in-center evaluation; some featured in-home visits by rehabilitation professionals. In 6 of the 11 studies, only walking exercise was prescribed. Only 3 included 2-way audio/visual patient-therapist contact. With regard to exercise outcomes; in 3, there was greater in-center group improvement; in 4, outcomes were similar; and, in 4, the in-center group failed to demonstrate clinically important exercise outcome increases; decidedly mixed results. Importantly, in 8 of 11 studies, the 6-min walk test was an exercise outcome. It is argued that the 6-min walk test does not generally elicit physiologically maximum responses and cannot be used to assess exercise capacity improvements. Of the 4 studies that used other exercise outcomes, in 2, exercise endurance increase was similar between in-home and in-center groups; in the other 2, the in-center group had superior improvements. Mixed results indeed! In conclusion, there is insufficient evidence to conclude that in-home pulmonary rehabilitation yields improvements equivalent to center-based programs in physical function, the outcome likely driving long-term prognosis. Moreover, it needs to be established which of the wide variety of in-home program designs now being offered should be promoted.

Counterpoint: In-Home Pulmonary Rehabilitation Is an Attractive Alternative

Center-based pulmonary rehabilitation is positioned as the accepted standard for pulmonary rehabilitation. There, however, are several barriers to its utilization, and usage rates remain as low as 4%, despite decades of trying to improve access. The question then arises as to who is really benefiting from center-based pulmonary rehabilitation as this therapy is barely available to eligible patients. Alternative modes of delivery of pulmonary rehabilitation have been tested. Meta-analyses indicate that these alternate modes are associated with clinical improvements comparable with center-based pulmonary rehabilitation in several outcomes that are important for patients, including the 6-min walk distance, dyspnea, and quality of life. These modes are also associated with better adherence to the intervention than center-based pulmonary rehabilitation. Telehealth pulmonary rehabilitation and home-based pulmonary rehabilitation, therefore, are attractive alternatives to center-based pulmonary rehabilitation and will exponentially increase pulmonary rehabilitation capacity.

The Effect of 14-Day Consumption of Hydrogen-Rich Water Alleviates Fatigue but Does Not Ameliorate Dyspnea in Long-COVID Patients: A Pilot, Single-Blind, and Randomized, Controlled Trial

(1) Background: Hydrogen (H2) may be a potential therapeutic agent for managing Long COVID symptoms due to its antioxidant and anti-inflammatory properties. However, more scientific literature is needed to describe the effects of H2 administration on treating symptoms. A study aimed to investigate the impact of hydrogen-rich water (HRW) administration on the fatigue and dyspnea of Long-COVID patients for 14 consecutive days. (2) Methods: In this randomized, single-blind, placebo-controlled study, 55 participants were recruited, and 23 of them were excluded. A total of 32 eligible participants were randomized into a hydrogen-rich water (HRW) group (n = 16) and a placebo water (PW) group (n = 16) in which they were instructed to consume hydrogen-rich water or placebo water for 14 days, respectively. The participants completed the Fatigue Severity Scale (FSS), Six-Minute Walk Test (6MWT), 30 s Chair Stand Test (30s-CST), Modified Medical Research Council Dyspnea Rating Scale (mMRC), Pittsburgh Sleep Quality Index (PSQI), and depression anxiety stress scale (DASS-21) before and after the intervention. A linear mixed-effects model was used to analyze the effects of HRW. Cohen's d values were used to assess the effect size when significance was observed. The mean change with 95% confidence intervals (95% CI) was also reported. (3) Results: The effects of HRW on lowering FSS scores (p = 0.046, [95% CI = -20.607, -0.198, d = 0.696] and improving total distance in the 6WMT (p < 0.001, [95% CI = 41.972, 61.891], d = 1.010), total time for the 30s-CST (p = 0.002, [95% CI = 1.570, 6.314], d = 1.190), and PSQI scores (p = 0.012, [95% CI = -5.169, 0.742], d = 1.274) compared to PW were of a significantly moderate effect size, while there was no significant difference in mMRC score (p = 0.556) or DASS-21 score (p > 0.143). (4) Conclusions: This study demonstrates that HRW might be an effective strategy for alleviating fatigue and improving cardiorespiratory endurance, musculoskeletal function, and sleep quality. Still, it does not ameliorate dyspnea among Long-COVID patients.

Validation of Constant Work Rate Cycling Endurance Time for Use in Chronic Obstructive Pulmonary Disease Clinical Trials

Rationale: A COPD Foundation working group sought to identify measures of exercise endurance, a meaningful aspect of physical functioning in everyday life among patients with chronic obstructive pulmonary disease (COPD) that is not fully accepted in regulatory decision making, hampering drug development. Objectives: To demonstrate, as we previously asserted (Casaburi COPD 2022;9:252), that constant work rate cycling endurance time is an appropriate exercise endurance measure in patients with COPD. Methods: To validate this assertion, we assembled an integrated database of endurance time responses, including 8 bronchodilator (2,166 subjects) and 15 exercise training (3,488 subjects) studies (Casaburi COPD 2022;9:520). Results: Construct validity was demonstrated: 1) peak physiologic and perceptual responses were similar for constant work rate and incremental cycling; 2) after bronchodilator therapy, there were greater increases in endurance time in patients with more severe airflow limitation; 3) after exercise training, endurance time increases were similar across airflow limitation severities; and 4) there were correlations between changes in endurance time and changes in mechanistically related physiologic and perceptual variables. Test-retest reliability was demonstrated, with consistency of changes in endurance time at two time points after the intervention. Responsiveness was confirmed, with significant increases in endurance time after active (but not placebo) bronchodilator therapy, with greater increases seen with more severe airflow limitation and after exercise training. On the basis of regression analysis using multiple anchor variables, the minimum important difference for endurance time increase is estimated to be approximately 1 minute. Conclusions: Constant work rate cycling endurance time is a valid exercise endurance measure in COPD, suitable for contributing to the evaluation of treatment benefit supporting regulatory decision making and evidence-based therapeutic recommendations.

Clinical utilization of airway inflammatory biomarkers in the prediction and monitoring of clinical outcomes in patients with chronic obstructive pulmonary disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) accounts for 545 million people living with chronic respiratory disorders and is the third leading cause of morbidity and mortality around the world. COPD is a progressive disease, characterized by episodes of acute worsening of symptoms such as cough, dyspnea, and sputum production.

AREAS COVERED

Airway inflammation is a prominent feature of COPD. Chronic airway inflammation results in airway structural remodeling and emphysema. Persistent airway inflammation is a treatable trait of COPD and plays a significant role in disease development and progression. In this review, the authors summarize the current and emerging biomarkers that reveal the heterogeneity of airway inflammation subtypes, clinical outcomes, and therapeutic response in COPD.

EXPERT OPINION

Airway inflammation can be broadly categorized as eosinophilic (type 2 inflammation) and non-eosinophilic (non-type 2 inflammation) in COPD. Currently, blood eosinophil counts are incorporated in clinical practice guidelines to identify COPD patients who are at a higher risk of exacerbations and lung function decline, and who are likely to respond to inhaled corticosteroids. As new therapeutics are being developed for the chronic management of COPD, it is essential to identify biomarkers that will predict treatment response.

Mortality prevention as the centre of COPD management

COPD is a major healthcare problem and cause of mortality worldwide. COPD patients at increased mortality risk are those who are more symptomatic, have lower lung function and lower diffusing capacity of the lung for carbon monoxide, decreased exercise capacity, belong to the emphysematous phenotype and those who have concomitant bronchiectasis. Mortality risk seems to be greater in patients who experience COPD exacerbations and in those who suffer from concomitant cardiovascular and/or metabolic diseases. To predict the risk of death in COPD patients, several composite scores have been created using different parameters. In previous years, large studies (also called mega-trials) have evaluated the efficacy of different therapies on COPD mortality, but until recently only nonpharmaceutical interventions have proven to be effective. However, recent studies on fixed combinations of triple therapy (long-acting β-agonists, long-acting muscarinic antagonists and inhaled corticosteroids) have provided encouraging results, showing for the first time a reduction in mortality compared to dual therapies. The aim of the present review is to summarise available data regarding mortality risk in COPD patients and to describe pharmacological therapies that have shown effectiveness in reducing mortality.

Influence of physical activity on the prognosis of COPD patients: the HADO.2 score - health, activity, dyspnoea and obstruction

Objective

The aim of this study was to create a prognostic instrument for COPD with a multidimensional perspective that includes physical activity (PA). The score also included health status, dyspnoea and forced expiratory volume in 1 s (HADO.2 score).

Methods

A prospective, observational, non-intervention study was carried out. Patients were recruited from the six outpatient clinics of the respiratory service of a single university hospital. The component variables of the HADO.2 score and BODE index were studied, and PA was measured using an accelerometer. The outcomes for the HADO.2 score were mortality and hospitalisations during follow-up and an exploration of the correlation with health-related quality of life at the moment of inclusion in the study.

Results

401 patients were included in the study and followed up for three years. The HADO.2 score showed good predictive capacity for mortality: C-index 0.79 (0.72-0.85). The C-index for hospitalisations was 0.72 (0.66-0.77) and the predictive ability for quality of life, as measured by R2, was 0.63 and 0.53 respectively for the Saint George's Respiratory Questionnaire and COPD Assessment Test.

Conclusions

There was no statistically significant difference between the mortality predictive capacity of the HADO.2 score and the BODE index. Adding PA to the original BODE index significantly improved the predictive capacity of the index. The HADO.2 score, which includes PA as a key variable, showed good predictive capacity for mortality and hospitalisations. There were no differences in the predictive capacity of the HADO.2 score and the BODE index.

Prognostic Value of Pace Variability, a Novel 6MWT-Derived Feature, in Patients with Chronic Obstructive Pulmonary Disease

Purpose

The 6-minute walk test (6MWT) is often used to evaluate chronic obstructive pulmonary disease (COPD) patients' functional capacity, with 6-minute walk distance (6MWD) and related measures being linked to mortality and hospitalizations. This study investigates the prognostic value of pace variability, a significant indicator in sports medicine, during the 6MWT for COPD patients.

Patients and Methods

We retrospectively screened consecutive COPD patients who had been prospectively enrolled in a pay-for-performance program from January 2019 to May 2020 to determine their eligibility. Patient characteristics, including demographics, exacerbation history, and 6MWT data, were analyzed to investigate their potential associations with prognosis. The primary outcome was a composite of adverse events, including overall mortality or hospitalizations due to exacerbations during a 1-year follow-up period. To analyze the 6MWT data, we divided it into three 2-minute epochs and calculated the average walk speed for each epoch. We defined pace variability as the difference between the maximum and minimum average speed in a single 2-minute epoch, divided by the average speed for the entire 6-minute walk test.

Results

A total of 163 patients with COPD were included in the study, and 19 of them (12%) experienced the composite adverse outcome. Multivariable logistic regression analyses revealed that two predictors were independently associated with the composite outcome: % predicted 6MWD <72 (adjusted odds ratio [aOR] 7.080; 95% confidence interval [CI] 1.481-33.847) and pace variability ≥0.39 (aOR 9.444; 95% CI 2.689-33.170). Patients with either of these adverse prognostic features had significantly worse composite outcome-free survival, with both log-rank P values less than 0.005. Notably, COPD patients with both adverse features experienced an especially poor outcome after 1 year.

Conclusion

Patients with COPD who exhibited greater pace variability during the 6MWT had a significantly higher risk of overall mortality and COPD-related hospitalizations, indicating a worse prognosis.

Validity and clinical applicability of the 60-secondecond sit-to-stand test in people with acute exacerbations of COPD

BACKGROUND

The 60-second sit-to-stand test (60STS) is a simple and increasingly popular test of physical function, however evidence to support its appropriateness for assessing people with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) is lacking.

AIMS

To evaluate the concurrent, convergent, predictive and discriminant validity, and responsiveness of the 60STS against the six-minute walk test (6MWT) in people hospitalised due to AECOPD.

METHODS

Prospective cohort study involving 54 inpatients with AECOPD (53% males, mean age 69.0 years, FEV1 46.5% predicted). 60STS was performed 30 min after a six-minute walk test (6MWT) upon discharge, with follow-up testing repeated one-month later (n = 39). Outcome measures included 60STS repetitions (60STSr), six-minute walk distance (6MWD), heart rate, oxyhaemoglobin saturation (SpO2), perceived dyspnoea (Borg scale), and rate of perceived exertion (RPE). Concurrent validity was assessed via correlation, convergent validity via Bland-Altman plots, predictive validity via multivariate linear regression (adjusted for confounders), discriminant validity via unpaired t tests and responsiveness via Chi (Jenkins, 2007) [2] tests.

RESULTS

Discharge 60STSr and 6MWD were strongly correlated (r = 0.61). Bland-Altman plots for nadir SpO2, peak HR, Borg and RPE scores showed acceptable agreement in terms of mean differences, but wide limits of agreement. Poor 60STSr performers were older, had weaker quadriceps, and had lower 6MWD than high performers (p < 0.05 for all). 60STSr was not retained as a significant predictor of 6MWD in multivariate regression analyses. 80% of 60STSr improvers also improved >30m on 6MWT at follow-up.

CONCLUSION

The 60STS demonstrates satisfactory validity and responsiveness as a measure of exercise performance in people with AECOPD.

Feasibility, effectiveness and safety of self-management in pulmonary rehabilitation: a study protocol using a hybrid type 1 effectiveness-implementation design

Background

As population ageing accelerates worldwide, chronic diseases will place an increasing burden on society and healthcare systems. Self-management interventions may become a key strategy for addressing chronic disease burden and healthcare costs, also in pulmonary rehabilitation (PR). One of the challenges here is long-term adherence. Understanding the level of adherence to PR may help inform clinical decision-making to focus more on self-management and less on clinical supervision. For this reason, a prediction model (PATCH) was developed. The presented protocol concerns a study that aims 1. to evaluate the safety and effectiveness of self-management within pulmonary rehabilitation (PR) on health outcomes in patients with chronic obstructive pulmonary disease (COPD), 2. to evaluate the predictive validity of the PATCH tool, and 3. to evaluate feasibility and acceptability of self-management and the PATCH tool by patients and physiotherapists.

Methods and analysis

This is a protocol of a hybrid type 1 effectiveness-implementation design, performed in primary physiotherapy practices in The Netherlands. The aim is to include 108 patients with COPD who have already followed PR for at least six weeks (maintenance stage of PR). According to the Dutch KNGF Guideline COPD, physiotherapists should reduce the number of supervised treatments after the maintenance phase and support self-management. In practice, this does not (always) happen. This protocol is based on implementing guideline advice: clinical supervision will be halved but patients are stimulated to engage in self-management by exercising unsupervised, leading to no change in the total planned exercise frequency. During the supervised sessions physiotherapists will assess and stimulate self-management. At baseline, and after 3, 6, 9 and 12 months, health outcomes (including adherence) will be evaluated as the primary outcome of this study. At each measurement, the physiotherapist will decide on the basis of individual scores whether the patient needs more clinical supervision or not. Secondary outcomes are the discriminatory power of the PATCH tool (can patients be correctly classified as adherent or non-adherent), and feasibility and acceptability of self-management and the PATCH tool by patients and physiotherapists. Questionnaires and semi-structured interviews will be used for assessment of the outcomes.Trial registration number: METc 2023/074.

Chronic Obstructive Pulmonary Disease Patients With High Peripheral Blood Eosinophil Counts Have Better Predicted Improvement in 6MWD After Rehabilitation: A PRELIMINARY STUDY

PURPOSE

The objective of this investigation was to determine whether chronic obstructive pulmonary disease (COPD) patients with high blood eosinophil (EOS) counts had better improvement in 6-min walk test (6MWT) after pulmonary rehabilitation (PR).

METHODS

Fifty COPD patients were randomly assigned to either the rehabilitation group (RG) or the control group (CG). Patients in the RG (8 wk PR + routine medication) and the CG (routine medication) were followed for 32 wk. According to the blood EOS level, the RG was divided into an EOS ≥ 200 cells/μL group and EOS < 200 cells/μL group. The 6MWT distance, Borg Scale, and COPD Assessment Test (CAT) were evaluated before intervention and 8 wk and 32 wk later.

RESULTS

After the 8-wk intervention, 37 patients (19 RG/18 CG) completed the study. At 8-wk and 32-wk follow-up from baseline, a statistically significant difference was found between these two groups in the 6MWT, Borg Scale, and CAT. Compared with baseline, the 6MWT in the RG increased 49.1 ± 40.2 m (95% CI, 29.7-68.5, P < .001) at 8 wk and 60.8 ± 42.1 m (95% CI, 40.5-81.6, P < .001) at 32 wk. In addition, the improvement of 6MWT in the EOS ≥ 200 cells/μL RG group was higher than that in the EOS < 200 cells/μL group (40.1 ± 17.6 m, 95% CI, 36.8-43.4; P = .036) at 32-wk follow-up from baseline.

CONCLUSION

An 8-wk PR can improve the exercise capacity of COPD patients, and the benefits persistent for 24 wk. The improvement in the 6MWT was more significant in COPD patients with a high blood EOS count.

Continuous Monitoring of Pulse Oximetry During the 6-Minute Walk Test Improves Clinical Outcomes Prediction in COPD

BACKGROUND

Continuous monitoring of SpO2 throughout the 6-min walk test (6MWT) unveiled that some patients with respiratory diseases may present values across the test lower than SpO2 measured at the end of the test. Nevertheless, it remains unclear whether this approach improves the yield of walk-induced desaturation detection in predicting mortality and hospitalizations in patients with COPD.

METHODS

Four hundred twenty-one subjects (51% males) with mild-very severe COPD underwent a 6MWT with continuous measurement of SpO2 . Exercise desaturation was defined as a fall in SpO2 ≥ 4%. All-cause mortality was assessed up to 6 y of follow-up and the rate of hospitalizations in the year succeeding the 6MWT.

RESULTS

One hundred forty-nine subjects (35.4%) died during a mean (interquartile) follow-up of 55.5 (30.2-64.1) months. Desaturation was observed in 299/421 (71.0%). SpO2 along the test was < end SpO2 (88 [82-92]% vs 90 [84-93]%, P < .001). Desaturation detected only during (but not at the end of) the test was found in 81/421 (19.2%) participants. Multivariate Cox regression model adjusted for sex, body composition, FEV1, residual volume/total lung capacity ratio, walk distance, O2 supplementation during the test, and comorbidities retained the presence of desaturation either at the end (1.85 [95% CI 1.02-3.36]) or only along the test (2.08 [95% CI 1.09-4.01]) as significant predictors of mortality. The rate of hospitalizations was higher in those presenting with any kind of desaturation compared to those without exercise desaturation. Logistic regression analysis revealed that walking interruption and diffusing capacity of the lung for carbon monoxide predicted desaturation observed only during the test.

CONCLUSIONS

O2 desaturation missed by end-exercise SpO2 but exposed by measurements during the test was independently associated with all-cause mortality and hospitalizations in subjects with COPD.

Increased chest CT derived bone and muscle measures capture markers of improved morbidity and mortality in COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a disease of accelerated aging and is associated with comorbid conditions including osteoporosis and sarcopenia. These extrapulmonary conditions are highly prevalent yet frequently underdiagnosed and overlooked by pulmonologists in COPD treatment and management. There is evidence supporting a role for bone-muscle crosstalk which may compound osteoporosis and sarcopenia risk in COPD. Chest CT is commonly utilized in COPD management, and we evaluated its utility to identify low bone mineral density (BMD) and reduced pectoralis muscle area (PMA) as surrogates for osteoporosis and sarcopenia. We then tested whether BMD and PMA were associated with morbidity and mortality in COPD.

METHODS

BMD and PMA were analyzed from chest CT scans of 8468 COPDGene participants with COPD and controls (smoking and non-smoking). Multivariable regression models tested the relationship of BMD and PMA with measures of function (6-min walk distance (6MWD), handgrip strength) and disease severity (percent emphysema and lung function). Multivariable Cox proportional hazards models were used to evaluate the relationship between sex-specific quartiles of BMD and/or PMA derived from non-smoking controls with all-cause mortality.

RESULTS

COPD subjects had significantly lower BMD and PMA compared with controls. Higher BMD and PMA were associated with increased physical function and less disease severity. Participants with the highest BMD and PMA quartiles had a significantly reduced mortality risk (36% and 46%) compared to the lowest quartiles.

CONCLUSIONS

These findings highlight the potential for CT-derived BMD and PMA to characterize osteoporosis and sarcopenia using equipment available in the pulmonary setting.

Stroke volume and cardiac output during 6 minute-walk tests are strong predictors of maximal oxygen uptake in people after stroke

Background and objectives

The 6-minute walk test (6MWT) is a field test commonly used to predict peak oxygen consumption (VO2peak) in people after stroke. Inclusion of cardiodynamic variables measured by impedance cardiography (ICG) during a 6MWT has been shown to improve prediction of VO2peak in healthy adults but these data have not been considered in people after stroke. This study investigates whether the prediction of VO2peak can be improved by the inclusion of cardiovascular indices derived by impedance cardiography (ICG) during the 6MWT in people after stroke.

Methods

This was a cross-sectional study. Patients diagnosed with stroke underwent in random order, a maximal cardiopulmonary exercise test (CPET) and 6MWT in separate dates. Heart rate (HR), stroke volume (SV) and cardiac output (CO) were measured by ICG during all tests. Oxygen consumption was recorded by a metabolic cart during the CPET. Recorded data were subjected to multiple regression analyses to generate VO2peak prediction equations.

Results

Fifty-nine patients, mean age 50.0±11.7 years were included in the analysis. The mean distance covered in the 6MWT (6MWD) was 294±13 m, VO2peak was 19.2±3.2 ml/min/kg. Mean peak HR, SV and CO recorded during 6MWT were 109±6 bpm, 86.3±8.8 ml, 9.4±1.2 L/min and during CPET were 135±14 bpm, 86.6±9 ml, 11.7±2 L/min respectively. The prediction equation with inclusion of cardiodynamic variables: 16.855 + (-0.060 x age) + (0.196 x BMI) + (0.01 x 6MWD) + (-0.416 x SV6MWT) + (3.587 x CO 6MWT) has a higher squared multiple correlation (R2) and a lower standard error of estimate (SEE) and SEE% compared to the equation using 6MWD as the only predictor.

Conclusion

Inclusion of SV and CO measured during the 6MWT in stroke patients further improved the VO2peak prediction power compared to using 6MWD as a lone predictor.

Lp-PLA2 as a biomarker and its possible associations with SARS-CoV-2 infection

Lp-PLA2 is an enzyme encoded by the PLA2G7 gene located at chromosome 6p12-21, which is included in different signal transduction pathways. The potential of serum levels of Lp-PLA2 as a marker of inflammation quantifying cardio-metabolic risk, renal impairment and oxidative stress has been explored in earlier studies. It has also been used in chronic obstructive pulmonary disease, hepatic disease, metabolic conditions and exercise tolerance. Additionally, it shows promising evidence for the assessment of risk for certain cardiovascular conditions in otherwise seemingly healthy individuals. COVID-19 has affected life and the economy globally. The identification of biomarkers to assess the sickness and treatment plan is the need of the hour. This review summarizes the pathophysiological inter-relationship between serum levels of Lp-PLA2 and COVID-19. The authors hypothesize that the estimation of Lp-PLA2 levels may help in the early identification of risk and thus may play a beneficial role in the proactive management of COVID-19.

The effectiveness of home-based balance and pulmonary rehabilitation program in individuals with chronic obstructive pulmonary disease: a randomized controlled trial

BACKGROUND

Balance impairment and increased fall risk have been demonstrated in individuals with chronic obstructive pulmonary disease (COPD). However, studies investigating the effects of balance training especially when combined with pulmonary rehabilitation (PR) program in home-based setting are scarce.

AIM

To examine whether adding balance training to home-based pulmonary rehabilitation improves balance, fall risk, and disease-related symptoms in individuals with COPD.

DESIGN

Randomized, controlled, assessor-blinded trial with parallel two-group design.

SETTING

Home-based setting.

POPULATION

Forty-eight individuals diagnosed with COPD.

METHODS

Participants with COPD were randomly allocated to either a home-based PR or home-based balance training combined with PR (PR-BT) group (24 per group). Both groups exercised three days per week for eight-week. Primary outcomes were fall risk index and functional balance as measured by the Physiological Profile Assessment (PPA) and Timed Up and Go (TUG), respectively. Secondary outcomes were the Activities-specific Balance Confidence (ABC), Modified Medical Research Council dyspnea (mMRC), Six-Minute Walk Test (6MWT), and COPD assessment test (CAT). All outcome measures were assessed at baseline, post-intervention, and three-month follow-up.

RESULTS

All participants completed the trial, with no reported adverse events. At post-intervention, the PR-BT group demonstrated significantly greater improvements in PPA fall risk score (PR-BT: 1.1±0.8, PR: 2.4±1.5), TUG (PR-BT: 10.7±1.3, PR: 14.4±4.4 s) and these improvements remained at three-month follow-up (all P<0.01). The ABC, mMRC, and CAT scores were also significant better for the PR-BT than the PR group both after intervention and at three-month follow-up (all P<0.05).

CONCLUSIONS

Eight-week home-based balance and PR program is effective in improving balance as well as dyspnea, and well-being in individuals with COPD.

CLINICAL REHABILITATION IMPACT

Home-based balance and PR program is a promising approach for COPD rehabilitation especially in patients who are at risk of falls.

"Can Do, Do Do" Quadrants and 6-Year All-Cause Mortality in Patients With COPD

BACKGROUND

Physical capacity (PC; "can do") and physical activity (PA; "do do") are prognostic indicators in COPD and can be used to subdivide patients with COPD into four exclusive subgroups (the so-called "can do, do do" quadrants). This concept may be useful to understand better the impact of PC and PA on all-cause mortality in patients with COPD.

RESEARCH QUESTION

What is the 6-year all-cause mortality risk of the "can do, do do" quadrants of patients with COPD?

STUDY DESIGN AND METHODS

This retrospective study used data from patients with COPD who underwent a comprehensive assessment at their first-ever outpatient consultation. PC was assessed using the 6-min walk distance and physical activity was assessed using an accelerometer (steps per day). All-cause mortality data were obtained from the Municipal Personal Records Database. Receiver operating characteristic curves were used to determine threshold values for PC and PA to predict 6-year all-cause mortality. Using the derived threshold values, male and female patients were divided into the four "can do, do do" quadrants.

RESULTS

Data from 829 patients were used for analyses. Best discriminatory values for 6-year mortality were 404 m and 4,125 steps/day for men and 394 m and 4,005 steps/day for women. During a median follow-up of 55 months (interquartile range, 37-71 months), 129 patients (15.6%) died. After controlling for established prognostic factors, patients in the "can do, don't do" quadrant and "can do, do do" quadrant showed significantly lower mortality risk compared with patients in the "can't do, don't do" quadrant: hazard ratios of 0.36 (95% CI, 0.14-0.93) and 0.24 (95% CI, 0.09-0.61) for men and 0.37 (95% CI, 0.38-0.99) and 0.29 (95% CI, 0.10-0.87) for women, respectively. No significant differences were found between the "can't do, do do" and "can't do, don't do" quadrants.

INTERPRETATION

Patients with COPD with a preserved PC seem to have a significantly lower 6-year mortality risk compared with patients with a decreased PC, regardless of physical activity level.

A Conceptual Framework for Use of Increased Endurance Time During Constant Work Rate Cycle Ergometry as a Patient-Focused Meaningful Outcome in COPD Clinical Trials

The Chronic Lung Disease Biomarker and Clinical Outcome Assessment Qualification Consortium (CBQC) evaluates the potential of biomarkers and outcome measures as drug development tools. Exercise endurance is an objective indicator of treatment benefit, closely related to daily physical function. Therefore, it is an ideal candidate for an outcome for drug development trials. Unfortunately, no exercise endurance measure is qualified by regulatory authorities for use in trials of chronic obstructive pulmonary disease (COPD) and no approved COPD therapies have claims of improving exercise endurance. Consequently, it has been challenging for developers to consider this outcome when designing clinical trials for new therapies. Endurance time during constant work rate cycle ergometry (CWRCE), performed on an electronically braked stationary cycle ergometer, provides an exercise endurance measure under standardized conditions. Baseline individualized work rate for each participant is set using an incremental test. During CWRCE the patient is encouraged to continue exercising for as long as possible. Although not required, physiological and sensory responses (e.g., pulmonary ventilation, heart rate, dyspnea ratings) are frequently collected to support interpretation of endurance time changes. Exercise tolerance limit is reached when the individual is limited by symptoms, unable to maintain pedaling cadence or unable to continue safely. At exercise cessation, exercise duration is recorded. An CWRCE endurance time increase from the pre-treatment baseline is proposed as a key efficacy endpoint in clinical trials. In COPD, improved exercise endurance has a direct relationship to the experience of physical functioning in daily life, which is a patient-centered, meaningful benefit.

Predictors of mortality in chronic obstructive pulmonary disease: a systematic review and meta-analysis

Background

Better insight in patients’ prognosis can help physicians to timely initiate advance care planning (ACP) discussions with patients with chronic obstructive pulmonary disease (COPD). We aimed to identify predictors of mortality.

Methods

We systematically searched databases Embase, PubMed, MEDLINE, Web of Science, and Cochrane Central in April 2020. Papers reporting on predictors or prognostic models for mortality at 3 months and up to 24 months were assessed on risk-of-bias. We performed a meta-analysis with a fixed or random-effects model, and evaluated the discriminative ability of multivariable prognostic models.

Results

We included 42 studies (49–418,251 patients); 18 studies were included in the meta-analysis. Significant predictors of mortality within 3–24 months in the random-effects model were: previous hospitalization for acute exacerbation (hazard ratio [HR] 1.97; 95% confidence interval [CI] 1.32–2.95), hospital readmission within 30 days (HR 5.01; 95% CI 2.16–11.63), cardiovascular comorbidity (HR 1.89; 95% CI 1.25–2.87), age (HR 1.48; 95% CI 1.38–1.59), male sex (HR 1.68; 95% CI 1.38–1.59), and long-term oxygen therapy (HR 1.74; 95% CI 1.10–2.73). Nineteen previously developed multicomponent prognostic models, as examined in 11 studies, mostly had moderate discriminate ability.

Conclusion

Identified predictors of mortality may aid physicians in selecting COPD patients who may benefit from ACP. However, better discriminative ability of prognostic models or development of a new prognostic model is needed for further large-scale implementation.

Registration: PROSPERO (CRD42016038494), https://www.crd.york.ac.uk/prospero/.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01911-5.

Chronic obstructive pulmonary disease risk assessment tools: is one better than the others?

PURPOSE OF REVIEW

Risk assessment tools are essential in COPD care to help clinicians identify patients at higher risk of accelerated lung function decline, respiratory exacerbations, hospitalizations, and death.

RECENT FINDINGS

Conventional methods of assessing risk have focused on spirometry, patient-reported symptoms, functional status, and a combination of these tools in composite indices. More recently, qualitatively and quantitatively assessed chest imaging findings, such as emphysema, large and small airways disease, and pulmonary vascular abnormalities have been associated with poor long-term outcomes in COPD patients. Although several blood and sputum biomarkers have been investigated for risk assessment in COPD, most still warrant further validation. Finally, novel remote digital monitoring technologies may be valuable to predict exacerbations but their large-scale performance, ease of implementation, and cost effectiveness remain to be determined.

SUMMARY

Given the complex heterogeneity of COPD, any single metric is unlikely to fully capture the risk of poor long-term outcomes. Therefore, clinicians should review all available clinical data, including spirometry, symptom severity, functional status, chest imaging, and bloodwork, to guide personalized preventive care of COPD patients. The potential of machine learning tools and remote monitoring technologies to refine COPD risk assessment is promising but remains largely untapped pending further investigation.

Malnutrition, Sarcopenia, and Malnutrition-Sarcopenia Syndrome in Older Adults with COPD

Purpose: Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the world population. In addition to airflow obstruction, COPD is associated with multiple systemic manifestations, including impaired nutritional status or malnutrition and changes in body composition (low muscle mass, LMM). Poor nutritional status and sarcopenia in subjects with COPD leads to a worse prognosis and increases health-related costs. Data from previous studies indicate that 30–60% of subjects with COPD are malnourished, 20–40% have low muscle mass, and 15–21.6% have sarcopenia. This study aimed to assess the prevalence of malnutrition, sarcopenia, and malnutrition-sarcopenia syndrome in elderly subjects with COPD and investigate the relationship between COPD severity and these conditions.Patients and methods: A cross-sectional study involving 124 patients with stable COPD, aged ≥60, participating in a stationary pulmonary rehabilitation program. Nutritional status was assessed following the Global Leadership Initiative on Malnutrition (GLIM) criteria and sarcopenia with the European Working Group on Sarcopenia in Older People 2 (EWGSOP2) criteria. The results of pulmonary function tests and exercise capacity were obtained from the hospital database. Results: 22.6% of participants had malnutrition according to the GLIM criteria. Subjects with malnutrition had lower gait speed (p = 0.0112) and worse results of the Six Minute Walk Test. Sixteen participants (12.9%) had sarcopenia; 12 subjects with sarcopenia had concomitant malnutrition. The prevalence of severe and very severe obstruction (GOLD3/GOLD4) was 91.7%. It was significantly higher in patients with malnutrition-sarcopenia syndrome. Conclusions: Malnutrition was found in nearly one out of four subjects with COPD, while sarcopenia was one out of seven patients. About 10% of our study sample had malnutrition-sarcopenia syndrome. The prevalence of severe and very severe obstruction was significantly higher in patients with malnutrition-sarcopenia syndrome.

Early Diagnosis and Real-Time Monitoring of Regional Lung Function Changes to Prevent Chronic Obstructive Pulmonary Disease Progression to Severe Emphysema

First- and second-hand exposure to smoke or air pollutants is the primary cause of chronic obstructive pulmonary disease (COPD) pathogenesis, where genetic and age-related factors predispose the subject to the initiation and progression of obstructive lung disease. Briefly, airway inflammation, specifically bronchitis, initiates the lung disease, leading to difficulty in breathing (dyspnea) and coughing as initial symptoms, followed by air trapping and inhibition of the flow of air into the lungs due to damage to the alveoli (emphysema). In addition, mucus obstruction and impaired lung clearance mechanisms lead to recurring acute exacerbations causing progressive decline in lung function, eventually requiring lung transplant and other lifesaving interventions to prevent mortality. It is noteworthy that COPD is much more common in the population than currently diagnosed, as only 16 million adult Americans were reported to be diagnosed with COPD as of 2018, although an additional 14 million American adults were estimated to be suffering from COPD but undiagnosed by the current standard of care (SOC) diagnostic, namely the spirometry-based pulmonary function test (PFT). Thus, the main issue driving the adverse disease outcome and significant mortality for COPD is lack of timely diagnosis in the early stages of the disease. The current treatment regime for COPD emphysema is most effective when implemented early, on COPD onset, where alleviating symptoms and exacerbations with timely intervention(s) can prevent steep lung function decline(s) and disease progression to severe emphysema. Therefore, the key to efficiently combatting COPD relies on early detection. Thus, it is important to detect early regional pulmonary function and structural changes to monitor modest disease progression for implementing timely interventions and effectively eliminating emphysema progression. Currently, COPD diagnosis involves using techniques such as COPD screening questionnaires, PFT, arterial blood gas analysis, and/or lung imaging, but these modalities are limited in their capability for early diagnosis and real-time disease monitoring of regional lung function changes. Hence, promising emerging techniques, such as X-ray phase contrast, photoacoustic tomography, ultrasound computed tomography, electrical impedance tomography, the forced oscillation technique, and the impulse oscillometry system powered by robust artificial intelligence and machine learning analysis capability are emerging as novel solutions for early detection and real time monitoring of COPD progression for timely intervention. We discuss here the scope, risks, and limitations of current SOC and emerging COPD diagnostics, with perspective on novel diagnostics providing real time regional lung function monitoring, and predicting exacerbation and/or disease onset for prognosis-based timely intervention(s) to limit COPD–emphysema progression.

Increased Vascular Endothelial Growth Factor Serum Level and the Role of +936C/T Gene Polymorphism in Chronic Obstructive Pulmonary Disease

Background and Objectives: Chronic obstructive pulmonary disease (COPD) represents a debilitating disease, with rising morbidity and mortality. Vascular endothelial growth factor (VEGF) plays a major role in angiogenesis, vascular permeability, and airway remodeling. The purpose of this study was to investigate the relationship between VEGF serum levels and VEGF +936 C/T gene polymorphism (rs3025039) with COPD, for the first time in a Romanian population. Materials and Methods: In total, 120 participants from Transylvania were included in this case-control study. Serum levels of VEGF were determined using an enzyme-linked immune-sorbent assay and rs3025039 was investigated by high molecular weight genomic deoxyribonucleic acid (DNA). Spirometric values, arterial blood gas analysis, and the Six Minute Walk Test (6MWT) outcome were also determined. Results: The serum level of VEGF was higher in the COPD group versus controls (p < 0.001), with a positive correlation with the 6MWT outcome. No significant difference was observed in the VEGF serum levels between VEGF +936C/T genotypes. There was no difference in the VEGF +936C/T genotype between COPD patients and healthy subjects (chi2 test p = 0.92, OR = 1.04, 95%CI = 0.41–2.62), but the presence of the T allele was significantly linked to the presence of COPD (chi2 test p = 0.02, OR = 2.36, 95%CI = 1.12–4.97). Conclusions: Higher VEGF serum levels were found in moderate and severe COPD and were positively correlated with the distance in the 6MWT. No significant difference was found between CC, CT, and TT genotypes of rs3025039 and the presence of COPD. The presence of the T allele was found to be linked to COPD and also to the degree of airway obstruction.

Chronotropic Index and Acute Exacerbations of Chronic Obstructive Pulmonary Disease: A Secondary Analysis of BLOCK COPD

Rationale: The chronotropic index quantifies the proportion of the expected heart rate increase that is attained during exercise. The relationship between the chronotropic index and acute exacerbations of chronic obstructive pulmonary disease (AECOPDs) has not been evaluated. Objectives: To determine whether a higher chronotropic index during a 6-minute walk (CI-6MW) is associated with lower risk of AECOPD and whether the CI-6MW is a marker of susceptibility to adverse effects of metoprolol in chronic obstructive pulmonary disease (COPD). Methods: We analyzed data from the BLOCK COPD (Beta-Blockers for the Prevention of AECOPDs) trial. We used Cox proportional hazards models to investigate the relationship between the CI-6MW and the time to AECOPDs. We also tested for interactions between study group assignment (metoprolol vs. placebo) and the CI-6MW on the time to AECOPDs. Results: Four hundred seventy-seven participants with exacerbation-prone COPD (mean forced expiratory volume in 1 second, 41% of predicted) were included in this analysis. A higher CI-6MW was independently associated with a decreased risk of AECOPDs of any severity (adjusted hazard ratio per 0.1 increase in CI-6MW of 0.88; 95% confidence interval, 0.80-0.96) but was not independently associated with AECOPDs requiring hospitalization (adjusted hazard ratio, 0.94; 95% confidence interval, 0.81-1.05). There was a significant interaction by treatment assignment, and in a stratified analysis, the protective effects of a higher CI-6MW on AECOPDs were negated by metoprolol use. Conclusions: A higher CI-6MW is associated with a decreased risk of AECOPDs and may be an indicator of susceptibility to the adverse effects of metoprolol.

A Home-Based Multimedia Pulmonary Rehabilitation Program Improves Clinical Symptoms and Physical Performance of Patients with Chronic Obstructive Pulmonary Disease

Home-based pulmonary rehabilitation can decrease symptoms in chronic obstructive pulmonary disease (COPD) patients. The purpose of this study was to compare the effects of a home-based pulmonary rehabilitation by instructive multimedia in the form of videos and flip charts on clinical symptoms and exercise performance in COPD patients. An eight-week home-based pulmonary rehabilitation program was performed with twenty COPD patients older than 60 years of age with moderate to severe stages. They were separated into two groups: a multimedia group (n = 10) and a control group, which was only provided with telephone monitoring (n = 10). Clinical symptoms were measured by using the clinical COPD questionnaire (CCQ), and exercise performance was measured using a six-minute walk test (6MWT) and an upper-lower limb muscle strengthening test. After 8 weeks, the results showed that both groups showed a statistically significant decrease in the CCQ (p < 0.05). The multimedia group showed a statistically significant increase in the lower-limb muscle strengthening (p < 0.05), while the control group was not found to show a statistically significant increase in the lower-limb muscle strengthening. Therefore, a pulmonary rehabilitation program using multimedia at home can lessen symptoms and improve exercise performance in COPD patients.

Blood Cadmium Levels and Oxygen Desaturation during the 6-Minute Walk Test in Patients with Chronic Obstructive Pulmonary Disease

Background and Objectives: chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation and a history of exposure to noxious stimuli. Cigarette smoking is the most important causal factor for developing COPD. Cadmium, a minor metallic element, is one of the main inorganic components in tobacco smoke. Inhaled cadmium was associated with a decline in lung function, gas exchange impairment, and the development of obstructive lung disease. Patients with COPD who had oxygen desaturation during the 6-min walk test (6MWT) had a significantly worse prognosis than non-desaturation in COPD patients. Nonetheless, few studies have addressed the influence of blood cadmium levels on exercise-induced oxygen desaturation in COPD patients. Our objective was to assess the potential impact of blood cadmium levels on oxygen desaturation during the 6MWT among COPD patients. Materials and Methods: we performed a retrospective analysis of patients with COPD who were examined for blood cadmium levels in a tertiary care referral center in Taiwan, between March 2020 and May 2021. The 6-min walk test was performed. Normal control subjects who had no evidence of COPD were also enrolled. Results: a total of 73 COPD patients were analyzed and stratified into the high-blood cadmium group (13 patients) and low-blood cadmium group (60 patients). A total of 50 normal control subjects without a diagnosis of COPD were enrolled. The high-blood cadmium group had a significantly higher extent of desaturation than the low-blood cadmium group. The frequency of desaturation during 6MWT revealed a stepwise-increasing trend with an increase in blood cadmium levels. A multivariable logistic regression model revealed that blood cadmium levels were independently associated with desaturation during the 6MWT (odds ratio 12.849 [95% CI 1.168-141.329]; p = 0.037). Conclusions: our findings indicate that blood cadmium levels, within the normal range, were significantly associated with desaturation during 6MWT in patients with COPD.

Peripheral blood microbial signatures in current and former smokers

The human microbiome has a role in the development of multiple diseases. Individual microbiome profiles are highly personalized, though many species are shared. Understanding the relationship between the human microbiome and disease may inform future individualized treatments. We hypothesize the blood microbiome signature may be a surrogate for some lung microbial characteristics. We sought associations between the blood microbiome signature and lung-relevant host factors. Based on reads not mapped to the human genome, we detected microbial nucleic acids through secondary use of peripheral blood RNA-sequencing from 2,590 current and former smokers with and without chronic obstructive pulmonary disease (COPD) from the COPDGene study. We used the Genome Analysis Toolkit (GATK) microbial pipeline PathSeq to infer microbial profiles. We tested associations between the inferred profiles and lung disease relevant phenotypes and examined links to host gene expression pathways. We replicated our analyses using a second independent set of blood RNA-seq data from 1,065 COPDGene study subjects and performed a meta-analysis across the two studies. The four phyla with highest abundance across all subjects were Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes. In our meta-analysis, we observed associations (q-value < 0.05) between Acinetobacter, Serratia, Streptococcus and Bacillus inferred abundances and Modified Medical Research Council (mMRC) dyspnea score. Current smoking status was associated (q < 0.05) with Acinetobacter, Serratia and Cutibacterium abundance. All 12 taxa investigated were associated with at least one white blood cell distribution variable. Abundance for nine of the 12 taxa was associated with sex, and seven of the 12 taxa were associated with race. Host-microbiome interaction analysis revealed clustering of genera associated with mMRC dyspnea score and smoking status, through shared links to several host pathways. This study is the first to identify a bacterial microbiome signature in the peripheral blood of current and former smokers. Understanding the relationships between systemic microbial signatures and lung-related phenotypes may inform novel interventions and aid understanding of the systemic effects of smoking.

Identifying a Heart Rate Recovery Criterion After a 6-Minute Walk Test in COPD

BACKGROUND

Slow heart rate recovery (HRR) after exercise is associated with autonomic dysfunction and increased mortality. What HRR criterion at 1-minute after a 6-minute walk test (6MWT) best defines pulmonary impairment?.

STUDY DESIGN AND METHODS

A total of 5008 phase 2 COPDGene (NCT00608764) participants with smoking history were included. A total of 2127 had COPD and, of these, 385 were followed-up 5-years later. Lung surgery, transplant, bronchiectasis, atrial fibrillation, heart failure and pacemakers were exclusionary. HR was measured from pulse oximetry at end-walk and after 1-min seated recovery. A receiver operator characteristic (ROC) identified optimal HRR cut-off. Generalized linear regression determined HRR association with spirometry, chest CT, symptoms and exacerbations.

RESULTS

HRR after 6MWT (bt/min) was categorized in quintiles: ≤5 (23.0% of participants), 6-10 (20.7%), 11-15 (18.9%), 16-22 (18.5%) and ≥23 (18.9%). Compared to HRR≤5, HRR≥11 was associated with (p<0.001): lower pre-walk HR and 1-min post HR; greater end-walk HR; greater 6MWD; greater FEV1%pred; lower airway wall area and wall thickness. HRR was positively associated with FEV1%pred and negatively associated with airway wall thickness. An optimal HRR ≤10 bt/min yielded an area under the ROC curve of 0.62 (95% CI 0.58-0.66) for identifying FEV1<30%pred. HRR≥11 bt/min was the lowest HRR associated with consistently less impairment in 6MWT, spirometry and CT variables. In COPD, HRR≤10 bt/min was associated with (p<0.001): ≥2 exacerbations in the previous year (OR=1.76[1.33-2.34]); CAT≥10 (OR=1.42[1.18-1.71]); mMRC≥2 (OR=1.42[1.19-1.69]); GOLD 4 (OR=1.98[1.44-2.73]) and GOLD D (OR=1.51[1.18-1.95]). HRR≤10 bt/min was predicted COPD exacerbations at 5-year follow-up (RR=1.83[1.07-3.12], P=0.027).

CONCLUSION

HRR≤10 bt/min after 6MWT in COPD is associated with more severe expiratory flow limitation, airway wall thickening, worse dyspnoea and quality of life, and future exacerbations, suggesting that an abnormal HRR≤10 bt/min after a 6MWT may be used in a comprehensive assessment in COPD for risk of severity, symptoms and future exacerbations.