[Prognostic value of clinical exercise testing in idiopathic pulmonary fibrosis]

Value of Cardiopulmonary Exercise Testing in Prognostic Assessment of Patients with Interstitial Lung Diseases

BACKGROUND

Interstitial lung disease (ILD) is associated with high rates of comorbidities and non-infectious lung disease mortality. Against this background, we aimed to evaluate the prognostic capacity of lung function and cardiopulmonary exercise testing (CPET) in patients with ILD.

MATERIALS AND METHODS

A total of 183 patients with diverse ILD entities were included in this monocentric analysis. Prediction models were determined using Cox regression models with age, sex, body mass index (BMI), and all parameters from pulmonary function testing and CPET. Kaplan-Meier curves were plotted for selected variables.

RESULTS

The median follow-up period was 3.0 ± 2.5 years. Arterial hypertension (57%) and pulmonary hypertension (38%) were the leading comorbidities. The Charlson comorbidity index score was 2 ± 2 points. The 3-year and 5-year survival rates were 68% and 50%, respectively. VO₂peak (mL/kg/min or %pred.) was identified as a significant prognostic parameter in patients with ILD. The cut-off value for discriminating mortality was 61%.

CONCLUSION

The present analyses consistently revealed the high prognostic power of VO₂peak %pred. and other parameters evaluating breathing efficacy (VÉ/VCO₂ @AT und VÉ/VCO₂ slope) in ILD patients. VO₂peak %pred., in contrast to the established prognostic values FVC %pred., DLCO/KCO %pred., and GAP, showed an even higher prognostic ability in all statistical models.

Cardiopulmonary exercise testing in interstitial lung diseases and the value of ventilatory efficiency

Interstitial lung diseases (ILDs) are diverse parenchymal pulmonary disorders, primarily characterised by alveolar and interstitial inflammation and/or fibrosis, and sharing pathophysiological similarities. Thus, patients generally harbour common respiratory symptoms, lung function abnormalities and modified exercise adaptation. The most usual and disabling complaint is exertional dyspnoea, frequently responsible for premature exercise interruption. Cardiopulmonary exercise testing (CPET) is increasingly used for the clinical assessment of patients with ILD. This is because exercise performance or dyspnoea on exertion cannot reliably be predicted by resting pulmonary function tests. CPET, therefore, provides an accurate evaluation of functional capacity on an individual basis. CPET can unmask anomalies in the integrated functions of the respiratory, cardiovascular, metabolic, peripheral muscle and neurosensory systems in ILDs. CPET uniquely provides an evaluation of all above aspects and can help clinicians shape ILD patient management. Preliminary evidence suggests that CPET may also generate valuable prognostic information in ILDs and can be used to shed light on the presence of associated pulmonary hypertension. This review aims to provide comprehensive and updated evidence concerning the clinical utility of CPET in ILD patients, with particular focus on the physiological and clinical value of ventilatory efficiency (V˙_E/V˙_CO2 ).

Value of Cardiopulmonary Exercise Testing in the Prognosis Assessment of Chronic Obstructive Pulmonary Disease Patients: A Retrospective, Multicentre Cohort Study

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is one of the most common chronic diseases associated with high mortality. Previous studies suggested a prognostic role for peak oxygen uptake (VO2peak) assessed during cardiopulmonary exercise testing (CPET) in patients with COPD. However, most of these studies had small sample sizes or short follow-up periods, and despite their relevance, CPET parameters are not included in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) tool for assessment of severity.

OBJECTIVES

We therefore aimed to assess the prognostic value of CPET parameters in a large cohort of outpatients with COPD.

METHODS

In this retrospective, multicentre cohort study, medical records of patients with COPD who underwent CPET during 2004-2017 were reviewed and demographics, smoking habits, GOLD grade and category, exacerbation frequency, dyspnoea score, lung function measurements, and CPET parameters were documented. Relationships with survival were evaluated using Kaplan-Meier analysis, Cox regression, and receiver operating characteristic (ROC) curves.

RESULTS

Of a total of 347 patients, 312 patients were included. Five-year and 10-year survival probability was 75% and 57%, respectively. VO2peak significantly predicted survival (hazard ratio: 0.886 [95% confidence interval: 0.830; 0.946]). The optimal VO2peak threshold for discrimination of 5-year survival was 14.6 mL/kg/min (area under ROC curve: 0.713). Five-year survival in patients with VO2peak <14.6 mL/kg/min versus ≥ 14.6 mL/kg/min was 60% versus 86% in GOLD categories A/B and 64% versus 90% in GOLD categories C/D.

CONCLUSIONS

We confirm that VO2peak is a highly significant predictor of survival in COPD patients and recommend the incorporation of VO2peak into the assessment of COPD severity.

A role for cardiopulmonary exercise testing in detecting physiological changes underlying health status in Idiopathic pulmonary fibrosis: a feasibility study

Introduction

There is limited data available on the use of CPET as a predictive tool for disease outcomes in the setting of IPF. We investigated the feasibility of undertaking CPET and the relationship between CPET and quality of life measurements in a well-defined population of mild and moderate IPF patients.

Methods

A prospective, single-centre observational study.

Results

Thirty-two IPF patients (mild n = 23, moderate n = 9) participated in the study, n = 13 mild patients attended for repeat CPET testing at 12 months. At baseline, total K-BILD scores and total IPF-PROM scores significantly correlated with 6MWT distance, but not with baseline FVC % predicted, TLco % predicted, baseline or minimum SpO₂. VO₂ peak/kg at AT positively correlated with total scores, breathlessness/activity and chest domains of the K-BILD questionnaire (p < 0.05). VO₂ peak significantly correlated with total IPF PROM scores and wellbeing domains (p < 0.05), with a trend towards statistical significance for total IPF-PROM and VO₂ peak/kg at anaerobic threshold (p = 0.06).

There was a statistically significant reduction in FVC% predicted at 12 months follow up, although the mean absolute decline was < 10% (p < 0.05). During this period VO₂ peak significantly reduced (21.6 ml/kg/min ± 2.9 vs 19.1 ± 2.8; p = 0.017), with corresponding reductions in total K-BILD and breathlessness/activity domains that exceeded the MCID for responsiveness. Lower baseline VO₂ peak/kg at anaerobic threshold correlated with greater declines in total K-BILD scores (r =  − 0.62, 0.024) at 12 months. Whilst baseline FVC% predicted or TLco % predicted did not predict change in health status,

Conclusion

We have shown that it is feasible to undertake CPET in patients with mild to moderate IPF.

CPET measures of VO₂ peak correlated with both baseline and change in K-BILD measurements at 1 year, despite relatively stable standard lung function (declines of < 10% in FVC), suggesting its potential sensitivity to detect physiological changes underlying health status.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01520-8.

The prognostic value of cardiopulmonary exercise testing in interstitial lung disease: a systematic review

The heterogeneity of interstitial lung disease (ILD) results in prognostic uncertainty concerning end-of-life discussions and optimal timing for transplantation. Effective prognostic markers and prediction models are needed. Cardiopulmonary exercise testing (CPET) provides a comprehensive assessment of the physiological changes in the respiratory, cardiovascular and musculoskeletal systems in a controlled laboratory environment. It has shown promise as a prognostic factor for other chronic respiratory conditions. We sought to evaluate the prognostic value of CPET in predicting outcomes in longitudinal studies of ILD.

MEDLINE, Embase and the Cochrane Database of Systematic Reviews were used to identify studies reporting the prognostic value of CPET in predicting outcomes in longitudinal studies of ILD. Study quality was assessed using the Quality in Prognosis Study risk of bias tool.

Thirteen studies were included that reported the prognostic value of CPET in ILD. All studies reported at least one CPET parameter predicting clinical outcomes in ILD, with survival being the principal outcome assessed. Maximum oxygen consumption, reduced ventilatory efficiency and exercise-induced hypoxaemia were all reported to have prognostic value in ILD. Issues with study design (primarily due to inherent problems of retrospective studies, patient selection and presentation of numerous CPET parameters), insufficient adjustment for important confounders and inadequate statistical analyses limit the strength of the conclusions that can be drawn at this stage.

There is insufficient evidence to confirm the value of CPET in facilitating “real-world” clinical decisions in ILD. Additional prospective studies are required to validate the putative prognostic associations reported in previous studies in carefully phenotyped patient populations.

There is presently insufficient evidence to confirm the value of CPET in facilitating “real-world” clinical decisions in ILD. Additional prospective studies are required to validate the putative prognostic associations reported in previous studies.https://bit.ly/3dfp5kq

Prognosis of idiopathic pulmonary fibrosis without anti-fibrotic therapy: a systematic review

In addition to facilitating healthcare delivery planning, reliable information about prognosis is essential for treatment decisions in patients with idiopathic pulmonary fibrosis (IPF). This review aimed to evaluate the prognosis of patients with IPF without anti-fibrotic therapy. We included all cohort studies and the placebo arms of randomised controlled trials (RCTs) in IPF and follow-up of ≥12 months. Two reviewers independently evaluated studies for inclusion, assessed risk of bias and extracted data. A total of 154 cohort studies and 16 RCTs were included. The pooled proportions of mortality were 0.12 (95% CI 0.09–0.14) at 1–2 years, 0.38 (95% CI 0.34–0.42) between 2–5 years, and 0.69 (95% CI 0.59–0.78) at ≥5 years. The pooled mean overall survival was 4 years (95% CI 3.7–4.6) for studies with a follow-up duration of 10 years. At <2 years, forced vital capacity and diffusing capacity of the lung for carbon monoxide declined by a mean of 6.76% predicted (95% CI −8.92 −4.61) and 3% predicted (95% CI −5.14 −1.52), respectively. Although heterogeneity was high, subgroup analyses revealed lower pooled proportions of mortality at 1 year in the RCT participants (0.07 (95% CI 0.05–0.09)) versus cohort study participants (0.14 (95% CI 0.12–0.17)). This review provides comprehensive information on the prognosis of IPF, which can inform treatment discussions with patients and comparisons for future studies with new therapies.

Without anti-fibrotic therapy, patients with IPF have a mortality rate of 31% at ≥5 years, and a mean overall survival of 4 years over 10 years of follow-uphttp://bit.ly/2SDiZSb

Cardiopulmonary Exercise Testing Allows Discrimination Between Idiopathic Non-specific Interstitial Pneumonia and Idiopathic Pulmonary Fibrosis in Mild to Moderate Stages of the Disease

It is unclear whether there are cardiopulmonary exercise testing (CPET) parameters which may indicate poor prognosis in the early course of fibrosing interstitial lung disease. 27 untreated consecutive subjects (13 idiopathic non-specific interstitial pneumonia (iNSIP), 14 idiopathic pulmonary fibrosis (IPF); 19 male; age 69 ± 10 years) were enrolled in this observational pilot study. Subjects underwent routine pulmonary function testing and CPET. Statistically, the t test and the Mann-Whitney-U test were applied in the presence of normal and non-normal distribution (according to Shapiro-Wilk), respectively. Analyzing the whole cohort, only mild functional impairments were determined. Comparison of iNSIP and IPF groups detected significant differences for the CPET parameters V'O₂Peak[%pred] (p = 0.011), V'O₂/kgPeak (p = 0.033), Watt[%pred] (p = 0.048), V'E/V'CO₂ (Rest: p = 0.016; AT: p = 0.011; Peak: p = 0.019; Slope: p = 0.040), V'E/V'O₂ (Rest: p = 0.033 AT: p = 0.014; Peak: p = 0.035). CPET parameters may indicate IPF-specific impairments even in mild disease. It may be hypothesized that these parameters are early biomarkers of poor prognosis.

8-Foot-Up-and-Go Test is Associated with Hospitalizations and Mortality in Idiopathic Pulmonary Fibrosis: A Prospective Pilot Study

PURPOSE

To assess the prognostic value of the 8-foot-up-and-go test (8-FUGT) in pilot cohort of patients with idiopathic pulmonary fibrosis (IPF).

METHODS

Thirty-four patients with IPF (68 ± 8 years) underwent 8-FUGT at baseline and were followed for up to 40 months. Receiver operating characteristics and age-adjusted Cox hazard ratios (HR) were analyzed for 8-FUGT, hospitalizations, and mortality. Correlation coefficients were determined between 8-FUGT and other exercise tests.

RESULTS

8-FUGT ≥ 6.9 s was found to be associated with hospitalization (sensitivity = 77%, specificity = 76%, p = 0.03) and mortality (sensitivity = 91%, specificity = 70% p = 0.008) in patients with IPF. Categorical models demonstrated that 8-FUGT ≥ 6.9 s was associated with 14.1- (p < 0.001) and 55.4-fold (p = 0.001) increased risks for hospitalization and mortality, respectively. In continuous models, for every 1-s slower performance in the 8-FUGT there were 54% [HR = 1.54, 95% CI (1.11-2.15) p = 0.01] increased risk for hospitalization and 94% [HR = 1.94, 95% CI (1.26-2.99) p = 0.003] increased risk for mortality. 8-FUGT was inversely related to 6-min walk distance (r = - 0.61), peak oxygen consumption (r = - 0.58), and peak work rate (r = - 0.72), all p < 0.001.

CONCLUSIONS

The 8-FUGT was strongly associated with hospitalizations and mortality in patients with IPF, as well as correlated with established prognostic markers. These novel findings suggest a prognostic value of the 8-FUGT for risk stratification, referral to pulmonary rehabilitation, and considering listing for lung transplantation. 8-FUGT is an inexpensive and practical tool that has prospective for implementation in clinical and research settings in IPF. Future prospective studies should evaluate the effect of changes in 8-FUGT on clinical outcomes.

TRIAL REGISTRATION

NCT01499745, Clinicaltrials.gov.

Exertional dyspnoea in interstitial lung diseases: the clinical utility of cardiopulmonary exercise testing

Interstitial lung diseases (ILDs) represent a heterogeneous group of pathologies characterised by alveolar and interstitial damage, pulmonary inflammation (usually associated with fibrosis), decreased lung function and impaired gas exchange, which can be attributed to either a known or an unknown aetiology. Dyspnoea is one of the most common and disabling symptoms in patients with ILD, significantly impacting quality of life. The mechanisms causing dyspnoea are complex and not yet fully understood. However, it is recognised that dyspnoea occurs when there is an imbalance between the central respiratory efferent drive and the response of the respiratory musculature. The respiratory derangement observed in ILD patients at rest is even more evident during exercise. Pathophysiological mechanisms responsible for exertional dyspnoea and reduced exercise tolerance include altered respiratory mechanics, impaired gas exchange, cardiovascular abnormalities and peripheral muscle dysfunction.

This review describes the respiratory physiology of ILD, both at rest and during exercise, and aims to provide comprehensive and updated evidence on the clinical utility of the cardiopulmonary exercise test in the assessment and management of these pathological entities. In addition, the role of exercise training and pulmonary rehabilitation programmes in the ILD population is addressed.

Physical Activity and Exertional Desaturation Are Associated with Mortality in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease that manifests in hypoxemia, inactivity, and poor prognosis. This study aimed to assess the prognostic role of physical activity (PA) and exertional desaturation (ED) with mortality in IPF. At baseline, 34 IPF patients (68 (50–81) years) were interviewed using the International Physical Activity Questionnaire (IPAQ), and SpO₂ was assessed pre to post 6-min walking test (∆SpO₂). Patients were prospectively followed up for 40 months. Receiver operating characteristics curve analysis determined cut-off points associated with mortality, and Cox proportional hazard ratio (HR) were conducted. Thresholds for increased mortality risk in IPF patients were determined as IPAQ ≤ 417 metabolic equivalent task (METS)-min/week, p = 0.004 (HR; 9.7, CI 95% (1.3–71.9), p = 0.027), and ∆SpO₂ ≥ 10%, p = 0.002, (HR; 23.3, CI 95% (1.5–365), p = 0.025). This study demonstrated a significant association of PA and ED with mortality in IPF patients. The findings emphasize the clinical importance of PA and ED assessments to aid in IPF risk stratification, prognosis prediction, and in providing early appropriate treatments, such as pulmonary rehabilitation, PA consultation, oxygen supplementation, and lung transplantation referral. These results underscore that even low levels of PA corresponding to 100–105 min/week were associated with a reduced mortality risk and better survival in IPF.

The Role of Cardiopulmonary Exercise Test in IPF Prognosis

Background. In IPF, defects in lung mechanics and gas exchange manifest with exercise limitation due to dyspnea, the most prominent and disabling symptom. Aim. To evaluate the role of exercise testing through the 6MWT (6-minute walk test) and CPET (cardiopulmonary exercise testing) in the survival of patients with IPF. Methods. This is a prospective, observational study evaluating in 25 patients the relationship between exercise variables through both the 6MWT and CPET and survival. Results. By the end of the observational period 17 patients were alive (33% mortality). Observation ranged from 9 to 64 months. VE/VCO₂ slope (slope of relation between minute ventilation and CO₂ production), VO₂ peak/kg (peak oxygen consumption/kg), VE/VCO₂ ratio at anaerobic threshold, 6MWT distance, desaturation, and DLCO% were significant predictors of survival while VE/VCO₂ slope and VO₂ peak/kg had the strongest correlation with outcome. The optimal model for mortality risk estimation was VO₂ peak/kg + DLCO% combined. Furthermore, VE/VCO₂ slope and VO₂ peak/kg were correlated with distance and desaturation during the 6MWT. Conclusion. The integration of oxygen consumption and diffusing capacity proved to be a reliable predictor of survival because both variables reflect major underlying physiologic determinants of exercise limitation.