Long-term oxygen therapy (LTOT) for patients with severe chronic hypoxemia is a well-established treatment, but data on long-term outcomes are limited. This study aims to describe the characteristics and survival of patients using LTOT in Belgium. Data from patients receiving LTOT were extracted from the Belgian Social Security databank with 4 years of follow-up and compared with a more detailed tertiary care cohort from the University Hospital of Leuven. Kaplan-Meier curves for overall and transplant-free survival were constructed. We performed log-rank univariate analyses for diagnosis and starting treatment modality and applied a Cox proportional hazards model adjusting for age and underlying diagnosis. In Belgium, 4973 patients started LTOT in 2017. Overall 4-year survival was 22% and determined by age, baseline oxygen modality and diagnosis. LTOT was primarily prescribed for patients with COPD (75%) who had higher 4-year survival (24%) compared to patients with restrictive pulmonary disease (17%) (HR 1.23, p < 0.005). In the University hospital cohort (n = 533), 4-year transplant-free survival was 26% with significantly lower survival rates of patients with ILD (13%) (HR 1.98, p < 0.005) and other obstructive lung diseases (24%) (HR 1.56, p < 0.01) as compared to COPD (33%). Survival for patients receiving LTOT remains poor. Best prognosis is seen in patients with COPD, while patients with restrictive pulmonary disease and ILD in particular have the poorest outcome. Palliative care and end-of-life discussions should be an integral part of prescribing LTOT.

This study aimed to investigate the impact of adherence to non-invasive ventilation (NIV) on the prognosis of patients with overlap syndrome (OS). This retrospective cohort study included 115 hospitalised patients with OS who initiated home NIV therapy and were followed up for 12 months. Adherence was classified as good (≥4 h/d) or poor (<4 h/d). Outcomes included annual exacerbation frequency, time to first exacerbation, severity of exacerbations, and St. George's Respiratory Questionnaire (SGRQ) scores. Initiating NIV treatment during hospitalisation was associated with a higher rate of NIV acceptance at home (33.99% vs. 11.34%, p < 0.001); however, there was no control group for treatment initiated on an outpatient basis. Good adherence significantly delayed the first acute exacerbation (log-rank test = 13.032, p < 0.001) and reduced the annual exacerbation rate (0.89 ± 0.86 vs. 1.24 ± 0.98, p = 0.041), but did not affect the severity of exacerbations. SGRQ scores at 6 and 12 months were better in the good adherence group (p < 0.05). There were no differences between groups in eosinophil counts or the use of benzodiazepines and opioids. This study demonstrates that good adherence to home NIV therapy following AECOPD significantly delays time to first exacerbation and reduces annual exacerbation frequency in patients with OS, while improving health-related quality of life. Additionally, in-hospital NIV initiation was associated with higher rates of home NIV acceptance compared to outpatient initiation, though this secondary finding requires prospective validation with appropriate comparator groups. These findings support the implementation of systematic screening and early intervention strategies for OS patients hospitalised for AECOPD.

Long-term smokers with persistent dyspnoea and exercise intolerance, who are at risk for COPD, require careful clinical assessment. However, many such individuals have only minor abnormalities on spirometry, and it is not known if various additional tests of small airways dysfunction (SAD) or pulmonary microvascular deficits, offer added clinical value. In this study we wished to determine which of the available resting pulmonary function tests (e.g. airway mechanics and lung diffusing capacity for carbon monoxide, DLCO) best uncover the physiological underpinnings of these troublesome respiratory symptoms. This tri-centre, prospective study enrolled 90 volunteers: 33 non-smoker controls, 57 symptomatic smokers, 38 of whom had Global Initiative for Obstructive Lung Disease Grade 1 COPD). Participants completed impulse oscillometry (IOS), spirometry, body plethysmography, DLCO, single and multiple breath nitrogen washout and an incremental cycle cardiopulmonary exercise test. Smokers had more diverse physiological abnormalities, greater dyspnoea and exercise intolerance than healthy controls. Stepwise multilinear regression revealed that DLCO was the only independent predictor of dyspnoea burden (ratio of peak dyspnoea score to peak oxygen uptake (V̇O2peak)), lower V̇O2peak, higher ventilatory equivalent for carbon dioxide (V̇E/V̇CO2 nadir) and dynamic inspiratory mechanical constraints (higher tidal volume to inspiratory capacity ratio), after accounting for age, sex, height, and smoking history. In symptomatic smokers, reduced DLCO, contributed more to the variance in exertional dyspnoea and exercise intolerance than all airway mechanical measurements. This attests to the added value of DLCO for clinicians assessing the nature and extent of smoking-related lung injury in individuals with only minor airway obstruction.

Dual long-acting bronchodilators are a standard treatment in chronic obstructive pulmonary disease (COPD), aimed at alleviating dyspnea, improving exercise tolerance, and preventing exacerbations. Metronome-paced tachypnea (MPT) offers a feasible alternative to exercise testing for the evaluation of dynamic hyperinflation (DH) in COPD. Because MPT can be performed during MRI, its combination with single-slice phase-resolved functional lung (PREFUL) MRI provides a promising approach to investigate changes in regional ventilation dynamics induced by DH. This approach was evaluated in a randomized, investigator-blinded, placebo-controlled, single-dose (SD) crossover trial with a two-week extension of once daily dual bronchodilator medication, in which patients with stable COPD underwent PREFUL MRI during resting tidal breathing (RTB) and during MPT. During RTB, no significant improvements in MRI-derived parameters were observed after SD treatment compared with placebo. During MPT, however, regional ventilation, flow-volume loop correlation, its defect percentage, and end-expiratory lung area improved significantly after SD treatment compared to the placebo scan (all p < 0.02). After multi-dose treatment, five out of six measured parameters improved during MPT, when compared to the baseline scan without bronchodilator treatment (all p < 0.03). In contrast to RTB, PREFUL MRI during MPT was able to detect changes in COPD patients already after SD treatment. The combination of MPT and PREFUL MRI represents a promising method to evaluate the effects of dual bronchodilators on regional ventilation dynamics and hyperinflation.

This corrects the article "Rationale and Design of the Roflumilast or Azithromycin to Prevent COPD Exacerbations Clinical Trial" in Volume 13, Issue 1, pp 17-28.

The causal relationship between chronic obstructive pulmonary disease (COPD) and respiratory tuberculosis (TB) remains unclear due to limited evidence from prospective studies. Therefore, this study aimed to assess the causal relationship between COPD and respiratory TB using a two-sample Bayesian weighted Mendelian randomization (BWMR) study. The genetic instrumental variants (IVs) for COPD and respiratory TB were obtained from the IEU Open GWAS project in 2021. The inverse variance weighted (IVW) method was used as the main statistical analysis method, and the results supplemented with weighted median and BWMR methods. Pleiotropy was tested using the MR-PRESSO global test and MR-Egger regression. Heterogeneity was analyzed using Cochran's Q statistics. The robustness of the results was tested using the leave-one-out sensitivity analysis method. In our two-sample BWMR analysis, we found that patients with COPD had a higher risk of respiratory TB based on IVW (OR = 1.259, 95% CI: 1.011-1.568; p = 0.040), weighted median (OR = 1.287, 95% CI: 0.981-1.688; p = 0 0.069), and BWMR (OR = 1.240, 95% CI: 1.013-1.518; p = 0.037). Reverse BWMR analysis showed that respiratory TB has no causal effect on COPD. We found no significant pleiotropy or heterogeneity in all selected IVs. The results were stable when removing the SNPs individually. This two-sample BWMR study provided strong evidence that individuals with COPD are at a higher risk of respiratory TB at the genetic level, while respiratory TB has no causal effect on COPD.