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Background: The Global Initiative for Obstructive Lung Disease (GOLD) does not promote diffusing capacity for carbon monoxide (Dlco) values in the evaluation of COPD. In GOLD spirometric stage I COPD patients, the clinical and prognostic impact of a low Dlco has not been explored., Research Question: Could a Dlco threshold help define an increased risk of death and a different clinical presentation in these patients?, Study Design and Methods: GOLD stage I COPD patients (n = 360) were enrolled and followed over 109 ± 50 months. Age, sex, pack-years' history, BMI, dyspnea, lung function measurements, exercise capacity, BODE index, and history of exacerbations were recorded. A cutoff value for Dlco was identified for all-cause mortality and the clinical and physiological characteristics of patients above and below the threshold compared. Cox regression analysis explored the predictive power of that cutoff value for all-cause mortality., Results: A Dlco cutoff value of <60% predicted was associated with all-cause mortality (Dlco ≥ 60%: 9% vs Dlco < 60%: 23%, P = .01). At a same FEV 1 % predicted and Charlson score, patients with Dlco < 60% had lower BMI, more dyspnea, lower inspiratory capacity (IC)/total lung capacity (TLC) ratio, lower 6-min walk distance (6MWD), and higher BODE. Cox multiple regression analysis confirmed that after adjusting for age, sex, pack-years history, smoking status, and BMI, a Dlco < 60% is associated with all-cause mortality (hazard ratio [HR], 95% CI = 3.37, 1.35-8.39; P = .009) INTERPRETATION: In GOLD I COPD patients, a Dlco < 60% predicted is associated with increased risk of death and worse clinical presentation. What the cause(s) of this association are and whether they can be treated need to be determined., (Copyright © 2021 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Background: FEV1 is universally used as a measure of severity in COPD. Current thresholds are based on expert opinion and not on evidence., Objectives: We aimed to identify the best FEV1 (% predicted) and dyspnea (mMRC) thresholds to predict 5-yr survival in COPD patients., Design and Methods: We conducted a patient-based pooled analysis of eleven COPD Spanish cohorts (COCOMICS). Survival analysis, ROC curves, and C-statistics were used to identify and compare the best FEV1 (%) and mMRC scale thresholds that predict 5-yr survival., Results: A total of 3,633 patients (93% men), totaling 15,878 person-yrs. were included, with a mean age 66.4 ± 9.7, and predicted FEV1 of 53.8% (± 19.4%). Overall 975 (28.1%) patients died at 5 years. The best thresholds that spirometrically split the COPD population were: mild ≥ 70%, moderate 56-69%, severe 36-55%, and very severe ≤ 35%. Survival at 5 years was 0.89 for patients with FEV1 ≥ 70 vs. 0.46 in patients with FEV1 ≤ 35% (H.R: 6; 95% C.I.: 4.69-7.74). The new classification predicts mortality significantly better than dyspnea (mMRC) or FEV1 GOLD and BODE cutoffs (all p<0.001). Prognostic reliability is maintained at 1, 3, 5, and 10 years. In younger patients, survival was similar for FEV1 (%) values between 70% and 100%, whereas in the elderly the relationship between FEV1 (%) and mortality was inversely linear., Conclusions: The best thresholds for 5-yr survival were obtained stratifying FEV1 (%) by ≥ 70%, 56-69%, 36-55%, and ≤ 35%. These cutoffs significantly better predict mortality than mMRC or FEV1 (%) GOLD and BODE cutoffs.

Rationale: Chronic obstructive pulmonary disease (COPD) is thought to result in rapid and progressive loss of lung function usually expressed as mean values for whole cohorts., Objectives: Longitudinal studies evaluating individual lung function loss and other domains of COPD progression are needed., Methods: We evaluated 1,198 stable, well-characterized patients with COPD (1,100 males) recruited in two centers (Florida and Tenerife, Spain) and annually monitored their multidomain progression from 1997 to 2009. Patients were followed for a median of 64 months and up to 10 years. Their individual FEV(1) (L) and BODE index slopes, expressed as annual change, were evaluated using regression models for repeated measures. A total of 751 patients with at least three measurements were used for the analyses., Measurements and Main Results: Eighteen percent of patients had a statistically significant FEV(1) slope decline (-86 ml/yr; 95% confidence interval [CI], -32 to -278 ml/yr). Higher baseline FEV(1) (relative risk, 1.857; 95% CI, 1.322-2.610; P < 0.001) and low body mass index (relative risk, 1.071; 95% CI, 1.035-1.106; P < 0.001) were independently associated with FEV(1) decline. The BODE index had a statistically significant increase (0.55, 0.20-1.37 point/yr) in only 14% of patients and these had more severe baseline obstruction. Concordance between FEV1 and BODE change was low (κ Cohen, 16%). Interestingly, 73% of patients had no significant slope change in FEV1 or BODE. Only the BODE change was associated with mortality in patients without FEV(1) progression., Conclusions: The progression of COPD is very heterogeneous. Most patients show no statistically significant decline of FEV(1) or increase in BODE. The multidimensional evaluation of COPD should offer insight into response to COPD management.

Rationale: The distance walked in the 6-min walk test (6MWT) predicts mortality in patients with severe COPD. Little is known about its prognostic value in patients with a wider range of COPD severity, living in different countries, and the potential additional impact of oxygen desaturation measured during the test., Methods: We enrolled 576 stable COPD outpatients in Spain and the United States and observed them for at least 3 years (median, 60 months). We measured FEV1, body mass index, Pao2, Charlson comorbidity score, 6-min walk distance (6MWD), and oxygen saturation by pulse oximetry (Spo2) during the 6MWT. Desaturation was defined as a fall in Spo2 > or = 4% or Spo2 < 90%. Regression analysis helped determine the association between these variables and all-cause and respiratory mortality., Results: The 6MWD was a good predictor of all-cause and respiratory mortality primarily in patients with FEV1 < 50% of predicted (p < 0.001) after adjusting for all covariates. Patients with desaturation during the 6MWT had a higher mortality rate than patients without desaturation (67% vs 38%, p < 0.001). Oxygen desaturation predicted mortality (relative risk, 2.63; 95% confidence interval, 1.53 to 4.51; p < 0.001) but with less power than Pao2 at rest., Conclusions: The 6MWD helps predict mortality primarily in patients with severe COPD. Although the oxygen desaturation profile during the 6MWT improves the predictive ability of the 6MWD, it appears to be of less relevance than in other lung diseases and than the resting Pao2.

Rationale: We had shown that COPD women expressed more dyspnea than men for the same degree of airway obstruction., Objectives: Evaluate gender differences in respiratory factors associated with dyspnea in COPD patients., Methods: In a FEV1 % matched population of 100 men and women with COPD we measured: age, MMRC, FEV1, FVC, TLC, IC/TLC, PaO2, PaCO2, DLCO, Pimax, P0.1, Ti/Ttot, BMI, ffmi, 6MWD and VAS scale before and after the test, the Charlson score and the SGRQ. We estimated the association between these parameters and MMRC scores. Multivariate analysis determined the independent strength of those associations., Results: MMRC correlated with: BMI (men:-0.29, p = 0.04; women:-0.28, p = 0.05), ffmi (men:-0.39, p = 0.01), FEV1 % (men:-0.64, p < 0.001; women:-0.29, p = 0.04), FVC % (men:-0.45, p = 0.001; women:-0.33, p = 0.02), IC/TLC (men:-0.52, p < 0.001; women: -0.27, p = 0.05), PaO2 (men:-0.59, p < 0.001), PaCO2 (men:0.27, p = 0.05), DLCO (men:-0.54, p < 0.001), P0.1/Pimax (men:0.46, p = 0.002; women:0.47, p = 0.005), dyspnea measured with the Visual Analog Scale before (men:0.37, p = 0.04; women:0.52, p = 0.004) and after 6MWD (men:0.52, p = 0.002; women:0.48, p = 0.004) and SGRQ total (men:0.50, p < 0.001; women:0.59, p < 0.001). Regression analysis showed that P0.1/Pimax in women (r2 = 0.30) and BMI, DLCO, PaO2 and P0.1/Pimax in men (r2 = 0.81) were the strongest predictors of MMRC scores., Conclusion: In mild to severe COPD patients attending a pulmonary clinic, P0.1/Pimax was the unique predictor of MMRC scores only in women. Respiratory factors explain most of the variations of MMRC scores in men but not in women. Factors other than the respiratory ones should be included in the evaluation of dyspnea in women with COPD.