eLetters

339 e-Letters

  • Bridging the gap between lung function trajectories and the clinic

    We read with great interest this latest valuable addition by Zhang et al. to the growing evidence describing lung function trajectories. Although a relatively small cohort, this study has remarkable retention of participants with lung function measurements from the age of 3 to 45 years, bridging the existing gap in the literature between birth cohort and mid-adult life studies. The authors identify ten FEV1 trajectories, notably more than previous studies, by using a best fitting model with an upper limit of twelve trajectories. Trajectories which rise and fall are of interest as potential targets for public health intervention. Whilst the parallel course of most trajectories identified thus far by this and other cohorts do not inspire confidence in modifiability, their 10-class model does reveal additional decline and catch-up groups not identified by a 6-class model in the supplement. This raises the question as to whether there has been an oversimplification in lung function trajectory modelling in previous analyses, which select between just three and six classes[1–4].

    Our interest was particularly sparked by data in supplementary figure S8 where individual lung function trajectories are displayed by class, in which FEV1 in the ‘persistently low’ trajectory demonstrated considerable variability. For clinicians, this individual variability is the hallmark of asthma, especially when combined with the strong association of childhood airway hyper-responsiveness. Th...

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  • Response to Letter to Editors

    We thank Professors Azuma and Raghu for their excellent suggestions and comments on our paper. Our study demonstrates the importance of pulmonary vascular resistance (PVR) as a prognostic factor in the initial evaluation of patients with interstitial lung disease (ILD) and highlights the greater significance of PVR over mPAP in right heart catheterisation (RHC) (1). We acknowledge that there is generally less emphasis on PVR compared to the more commonly discussed mean pulmonary arterial pressure (mPAP), and it was our intention to address this discrepancy with our study.
    It is important to clarify that we do not recommend systematic RHC at initial evaluation of ILD. Historically, our approach was to perform RHC more frequently at diagnosis, but in recent years, we have limited this to cases where pulmonary hypertension (PH) is suspected. We recently reported a system for predicting mPAP > 20mmHg using a Pa/Ao ratio ≥ 0.9, PaO2 < 80 Torr, and DLco percent predicted < 50% in patients with idiopathic pulmonary fibrosis (IPF) (2). We propose using this system to screen patients before undergoing RHC, with assessments of both mPAP and PVR.
    As Azuma and colleagues pointed out, exercise tolerance tests, including the 6-minute walk test (6MWT), might help in predicting PH. As patients with PH have significantly worse desaturation and walking distance in the 6MWT, those who show significant desaturation and/or reduced walking distance during 6MWT are likely to...

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  • Letter to Editors

    " We congratulate Sato et al to have undertaken the retrospective stud(y that surfaces clinical significance of pulmonary vascular resistance (PVR) as a predictor of mortality in patients with newly diagnosed ILD with normal mean MAP – i.e., < 30mmhg at rest ( 1) .

    While their obsrervation is interesting , are the authors advocating right heart catheterization(RHC) for patients with new onset ILD upfront at the time of initial evaluation undergoing diagnostic interventions for diagnosis of ILD ?

    Indeed, RHC is an invasive procedure, and the potential benefits and risks must be weighed in considering RHC for patients with new onset ILD for prognostication and consideration of possible therapeutic interventions. Are the authors recommending RHC for patients with new onset ILD without clues for pulmonary hypertension ?
    Do the authors have additional non invasive clinical variables/data that correlate with PVR > 2 wood units with mean PAP < 20 mmHg- such as decreased DLCO corrected for hemoglobin, oxygen desaturation with walking, extent of interstitial lung abnormalities , specific diagnosis in patients with new onset ILD that can be used to screen patients to undergo RHC ?
    Perhaps, a noninvasive method using an exercise test as was used in assessing patient's endurance of exercise in patients with IPF treated with pirfenidone for IPF(2) might be a screening test prior to considering RHC as a routine for patients with new ons...

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  • Continuous positive airway pressure in chronic hypercapnic respiratory failure

    Dear editor,
    I read with interest the state-of-the-art review article by Shah et al1. on the effects of non-invasive ventilation (NIV) on sleep in chronic hypercapnic respiratory failure. However, I wish to delve deeper into the topic of Continuous Positive Airway Pressure (CPAP) especially in patients with Chronic Obstructive Pulmonary Disease-Obstructive Sleep Apnea (COPD-OSA) overlap syndrome and obesity hypoventilation syndrome (OHS).
    COPD-OSA overlap syndrome was first described by Professor Flenley2, which is associated with an increased frequency and severity of COPD exacerbations3, hospitalizations3, and mortality4. Current data indicates that CPAP improves these outcomes5.
    Similarly, in OHS, OSA is highly prevalent, affecting an estimated 90% of patients with OHS6. CPAP has been demonstrated to offer similar benefits to NIV6 7 and is recommended as the initial treatment for stable OHS patients8. CPAP therapy enhances outcomes by improving ventilation, reducing air-trapping, enhancing diaphragmatic function, improving hypercapnic response, and decreasing CO2 production resulting from excessive respiratory muscle work9. Given its advantages and cost-effectiveness compared to NIV, CPAP devices should be considered the initial treatment option7 for both disease before NIV.

    Reference
    1. Shah NM, Steier J, Hart N, Kaltsakas G. Effects of non-invasive ventilation on sleep in chronic hypercapnic respiratory failure. Thorax 2023 doi: 10.1136...

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  • Baseline post-PE assessment

    Thank you to the authors for the excellent and very interesting work published.

    I would like to ask about the protocol routine follow-up of patients following an acute pulmonary embolus mentioned in the paper: what did this entail, and how did it differ from the protocol implemented as part of the trial?

    Secondly, how did the authors select a follow-up telephone at 2 years post acute pulmonary embolus? As is pointed out in the limitations of section of the paper, this could have missed patients with clinically significant CTEPH who did not survive those 2 years. Would an earlier symptom assessment have led to a greater incidence of false positive echocardiograms showing pulmonary hypertension, or would it lead to patients being missed as not enough time would have passed to allow CTEPH to establish?

    Thank you in advance for your clarifications

  • Underrepresentation of low- and middle-income countries in "Core outcome set for pulmonary rehabilitation of patients with COPD: results of a modified Delphi survey"

    If a core outcome set (COS) to a global burden of disease is to be globally relevant and applicable, methodological efforts to ensure equal representation of low- and middle-income countries (LMICs) and high-income countries (HICs) at all stages of its development are needed (1, 2). This is due to the differences in disease patterns, healthcare resources, culture, and biomedical beliefs, which may influence outcome priorities (3, 4). A case in point is a study by Van Rijssen et al (5), where participants from Europe, the USA, and Asia did not reach the same consensus on the final patient-reported COS for pancreatic cancer, and Asian participants did not reach a consensus on any outcomes included in the final set.

    We read with interest your COS for pulmonary rehabilitation (PR) of patients with COPD in the 2023 September issue of Thorax "(6). We noticed the under-representation of LMICs, especially in Asia and Africa, in your development of the COS. Of the 29 and 27 countries where you recruited participants in the first and second rounds of your Delphi survey, respectively, Asia was represented by only one participant from India, whilst no participant was recruited from Africa. Most participants were from HICs in Europe including the Netherlands, Portugal, United Kingdom, Australia, and Spain.

    This underrepresentation of LMICs is noteworthy given that, firstly, the burden of chronic respiratory diseases (including COPD) is greater in LMICs, both in terms...

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  • Response to "Underrepresentation of low- and middle-income countries"

    We thank Bickton and colleagues for their interest in reading our article and their commentary.
    We recognize the need to have a balanced representation of low- and middle-income countries (LMICs) in core outcome sets (COS), specifically in pulmonary rehabilitation (PR) as resources for measurement instruments may vary globally and the burden of COPD and need for pulmonary rehabilitation in these regions are undeniable.
    According to the World Bank categories (1), we have included some middle-income countries in our study, from south America (Argentina, Brazil, Colombia, Cuba) and from Asia (not only India, but also the Philippines). Nonetheless, as acknowledged in our COS paper (2), the African and Asian continents were underrepresented.
    Although not stated throughout our paper, with the a priori knowledge of the need to include these continents and LMICs, we took some methodological steps to try to ensure their representation. Indeed, we have contacted several professional and patient associations from these regions to help us recruit participants. The Pan African Thoracic Society was contacted directly. Nonetheless, the procedure to contact is a form on a website (https://panafricanthoracic.org/about-us/contact-us), with no other form of contact provided. No response was ever obtained. We congratulate the newly formed PR Working Group, and we look forward to enhancing our communication chan...

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  • Letter to the editors. The effect of vibrotactile PT on patient with positional obstructive sleep apnoea (POSA).

    The systematic review and meta-analysis by Abdullah ALQarni et al. on the effect of positional vibrotactile therapy for positional obstructive sleep apnoea shows that this treatment modality is effective, reducing time in the supine position, severity of obstructive sleep apnoea and daytime sleepiness. (1) It also highlights the lack of patient-centered outcomes beyond daytime sleepiness, which is very important to achieve good adherence to treatment, one of the main limitations of obstructive sleep apnoea treatment to achieve greater health benefits for patients as shown by different clinical trials that have failed to show significant results of continuous airway pressure (CPAP) in the prevention of cardiovascular events in intention-to-treat analyses but did show significant results in patients with good adherence to treatment (2).
    Based on this statement, we would like to refer you to our last publication (3), a RCT, which shows high good compliance rates for the active device (mean value of 85% ± 36.6%, defined as device use for more than 4 hours per night and more than 70% of nights per week), values above the usual ones for CPAP treatment, (generally 40%–50% in the long term)(4,5), from the first day and sustained form over time. Patient ́s satisfaction was high and minor side effects were reported.
    Our previous research showed their efficacy in terms of reduction of Apnoea-Hypopnoea Index, total sleep time in the supine position; improve oxygen saturati...

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  • Potential benefits of long-term pulmonary rehabilitation to preserve exercise capacity in patients with idiopathic pulmonary fibrosis treated with antifibrotic drugs.

    We were interested in the article "Long-term effect of pulmonary rehabilitation in idiopathic pulmonary fibrosis: a randomised controlled trial" by Kataoka K. et al. [1] The effect of pulmonary rehabilitation in patients with idiopathic pulmonary fibrosis (IPF) is a topical theme in this field. We believe that this multicenter randomised controlled trial conducted in Japan will have an enormous impact on the knowledge of pulmonary rehabilitation in patients with IPF.
    The authors conducted a 12-week supervised and home-based unsupervised exercise therapy-based pulmonary rehabilitation for 45 outpatients with IPF treated with antifibrotic drugs. In addition, the patients were followed by a 40-week home-based unsupervised exercise therapy-based maintenance program. The pulmonary rehabilitation resulted in a more significant change (week 52 - Baseline) in endurance time measured by a constant workload test using a bicycle ergometer compared to 43 control patients who received only usual care (mean difference: 187 s [95% CI: 34 to 153]). Although endurance time is a secondary outcome in the authors' study design, this result suggests that IPF patients treated with antifibrotic drugs may benefit from pulmonary rehabilitation as a combination therapy to maintain exercise tolerance.
    In contrast, the authors found no statistically significant between-group differences in the change in 6-minute walking distance (6MWD) (52 weeks - Baseline), the prima...

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  • Reply to Drs Abul-Ainine and Steer re: Aminophylline and the British Asthma Guidelines In Children
    Gary Connett

    Dear Editor

    Drs Abul-Ainine and Steer have provided cogent arguments for the use of a 10mg/kg loading dose of intravenous aminophylline to treat acute asthma in children.[1] Their pharmacokinetic evidence for this dose is supported by Yung et al’s randomised placebo controlled trial using this same loading dose.[2] This study recruited 163 children with severe acute asthma unresponsive to three nebulised doses...

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