Dyspnoea at 6-min walk test in idiopathic pulmonary fibrosis: Comparison with COPD

Clinical utility of the Borg dyspnoea score in 6-minute walk tests in interstitial lung disease: A systematic review

BACKGROUND

Exertional dyspnoea, a cardinal symptom in interstitial lung disease (ILD), can be objectively measured during a 6-min walk test (6MWT) using the Borg Dyspnoea Score (BDS). However, the clinical utility of this measurement is unclear. The purpose of this systematic review was to determine the association between 6MWT BDS and prognosis (mortality and lung transplantation), other 6MWT variables and measures of pulmonary function.

METHODS

MEDLINE, EMBASE, Cochrane and SCOPUS databases were used to identify studies reporting an association between post-6MWT BDS and the relevant outcomes in adults with ILD. Language was limited to English. Study quality was assessed using the Quality in Prognosis Study risk of bias tool. A narrative synthesis for each outcome was performed.

RESULTS

Ten full-text studies (n = 518) were included. Four studies had high overall risk of bias. Two studies (n = 127) reported prognosis and both found that higher 6MWT BDS was associated with increased all-cause mortality. However, the certainty of evidence was very low due to study design and likely publication bias. Higher post-6MWT BDS may be associated with shorter, or no effect on 6MWD; and lower pulmonary function. There was insufficient evidence that BDS correlated with 6MWT oxygen saturation.

CONCLUSIONS

Post-6MWT BDS has a potential role as a predictor of all-cause mortality in ILD, 6MWD and lower pulmonary function. Larger studies designed to confirm these relationships and assess the independent association between the 6MWT BDS and clinical outcomes are required.

Predicting New-onset Exertional and Resting Hypoxemia in Fibrotic Interstitial Lung Disease

Rationale: Hypoxemia in fibrotic interstitial lung disease (ILD) indicates disease progression and is of prognostic significance. The onset of hypoxemia signifies disease progression and predicts mortality in fibrotic ILD. Accurately predicting new-onset exertional and resting hypoxemia prompts appropriate patient discussion and timely consideration of home oxygen. Objectives: We derived and externally validated a risk prediction tool for both new-onset exertional and new-onset resting hypoxemia. Methods: This study used ILD registries from Canada for the derivation cohort and from Australia and the United States for the validation cohort. New-onset exertional and resting hypoxemia were defined as nadir oxyhemoglobin saturation < 88% during 6-minute-walk tests, resting oxyhemoglobin saturation < 88%, or the initiation of ambulatory or continuous oxygen. Candidate predictors included patient demographics, ILD subtypes, and pulmonary function. Time-varying Cox regression was used to identify the top-performing prediction model according to Akaike information criterion and clinical usability. Model performance was assessed using Harrell's C-index and goodness-of-fit (GoF) likelihood ratio test. A categorized risk prediction tool was developed. Results: The best-performing prediction model for both new-onset exertional and new-onset resting hypoxemia included age, body mass index, a diagnosis of idiopathic pulmonary fibrosis, and percent predicted forced vital capacity and diffusing capacity of carbon monoxide. The risk prediction tool exhibited good performance for exertional hypoxemia (C-index, 0.70; GoF, P = 0.85) and resting hypoxemia (C-index, 0.77; GoF, P = 0.27) in the derivation cohort, with similar performance in the validation cohort except calibration for resting hypoxemia (GoF, P = 0.001). Conclusions: This clinically applicable risk prediction tool predicted new-onset exertional and resting hypoxemia at 6 months in the derivation cohort and a diverse validation cohort. Suboptimal GoF in the validation cohort likely reflected overestimation of hypoxemia risk and indicated that the model is not flawed because of underestimation of hypoxemia.

Predictors of changes in 6-min walking distance following pulmonary rehabilitation in COPD patients: a retrospective cohort analysis

BACKGROUND

Pulmonary rehabilitation (PR) is fundamental in chronic obstructive pulmonary disease (COPD) management but not all patients may show functional benefits from PR.

AIM

The aim of this study was to identify predictors of non-response in functional capacity to PR.

DESIGN

Observational study.

SETTING

Inpatient pulmonary rehabilitation center.

POPULATION

COPD patients.

METHODS

This single center study is a retrospective analysis of data in COPD patients admitted to a PR center between January 2012 and December 2017. Post-PR change in 6-min walking distance (6MWD) was used to determine the functional response to PR. Patients characteristics and pre-PR 6-min walking test responses were analyzed to determine factors associated with post-PR changes in 6MWD.

RESULTS

Data from 835 patients were analyzed as well as a subgroup of 190 patients with additional variables available. Eighty percent of the patients showed clinically significant 6MWD improvement post-PR. The predictors of 6MWD response to PR were age, pre-PR 6MWD, pre-PR end-of-test dyspnea and long-term oxygen therapy. Older patients, longer pre-PR 6MWD, higher pre-PR end-of-test dyspnea score and the use of oxygen supplementation were associated with lesser post-PR 6MWD improvement.

CONCLUSIONS

This study identified four important clinical variables predicting a lack of 6MWD response to PR.

CLINICAL REHABILITATION IMPACT

Patients with such clinical characteristics may require specific PR modalities to improve their functional benefit.

Incidence and Prognostic Significance of Hypoxemia in Fibrotic Interstitial Lung Disease: An International Cohort Study

BACKGROUND

Hypoxemia is a cardinal feature of fibrotic interstitial lung disease (ILD). The incidence, progression, and prognostic significance of hypoxemia in patients with fibrotic ILD currently is unknown.

RESEARCH QUESTION

What are the epidemiologic features of hypoxemia and its additive prognostic value in a current risk prediction model of fibrotic ILD?

METHODS

We identified 848 patients with fibrotic ILD (258 with idiopathic pulmonary fibrosis [IPF]) in five prospective ILD registries from Australia, Canada, and Switzerland. Cumulative incidence of exertional and resting hypoxemia from the time of diagnosis was estimated at 1-year intervals in patients with baseline 6-min walk tests, adjusted for competing risks of death and lung transplantation. Likelihood ratio tests were used to determine the prognostic significance of exertional and resting hypoxemia for 1-year mortality or transplantation when added to the ILD-GAP model. The cohort was divided into derivation and validation subsets to evaluate performance characteristics of the extended model (the ILD-GAP-O₂ model), which included oxygenation status as a predictor.

RESULTS

The 1-, 2-, and 5-year overall cumulative incidence was 6.1%, 17.3%, and 40.1%, respectively, for exertional hypoxemia and 2.4%, 5.6%, and 16.5%, respectively, for resting hypoxemia, which were significantly higher in patients with IPF compared with patients without IPF (P < .001 for both). Addition of exertional or resting hypoxemia to the ILD-GAP model improved 1-year mortality and transplantation prediction (P < .001 for both). The ILD-GAP-O₂ model showed improved discrimination (C-index, 0.80 vs 0.75) and model fit (Akaike information criteria, 400 vs 422) in the validation cohort, with comparable calibration.

INTERPRETATION

Patients with IPF have higher cumulative incidence of exertional and resting hypoxemia than patients without IPF. The extended ILD-GAP-O₂ model provides additional risk stratification for 1-year prognosis in fibrotic ILD.

Respiratory Impairment, Limited Activity, and Pulmonary Rehabilitation in Patients with Interstitial Lung Disease

Interstitial lung disease (ILD) is a diverse group of chronic lung conditions characterized by dyspnea, exercise-induced hypoxemia (EIH), and exercise intolerance. Since activity limitations and impaired health-related quality of life (HRQoL) in ILD are similar to those in other chronic respiratory diseases, including chronic obstructive pulmonary disease (COPD), pulmonary rehabilitation is also indicated for patients with ILD. This rehabilitation program mainly comprises exercise training and self-management education. Exercise training is the most important component of pulmonary rehabilitation. It significantly improves dyspnea and enhances exercise capacity and HRQoL in patients with ILD. The standard exercise prescription used for COPD is also effective for ILD. However, considering that disease progression and exercise-limiting factors are different in patients with COPD is necessary. Severe EIH, the adverse effects of corticosteroid administration, and comorbidities often lead to difficulty in employing a sufficient exercise intensity. Some modifications in the exercise prescription for individual patients or strategies to minimize EIH and dyspnea are required to optimize training intensity. Since EIH is common and severe in patients with ILD, supplemental oxygen should be provided. In advanced and more severe patients, who have difficulty in performing exercises, energy conservation techniques and the use of energy-saving devices to improve and maintain the patients' activities of daily living may be effective．.

Physiology of the lung in idiopathic pulmonary fibrosis

The clinical expression of idiopathic pulmonary fibrosis (IPF) is directly related to multiple alterations in lung function. These alterations derive from a complex disease process affecting all compartments of the lower respiratory system, from the conducting airways to the lung vasculature. In this article we review the profound alterations in lung mechanics (reduced lung compliance and lung volumes), pulmonary gas exchange (reduced diffusing capacity, increased dead space ventilation, chronic arterial hypoxaemia) and airway physiology (increased cough reflex and increased airway volume), as well as pulmonary haemodynamics related to IPF. The relative contribution of these alterations to exertional limitation and dyspnoea in IPF is discussed.

Physiological impairment in IPF is complex and involves all compartments of the respiratory systemhttp://ow.ly/gyao30hdHUb

Increased hemoglobin-oxygen affinity ameliorates bleomycin-induced hypoxemia and pulmonary fibrosis

Although exertional dyspnea and worsening hypoxia are hallmark clinical features of idiopathic pulmonary fibrosis (IPF), no drug currently available could treat them. GBT1118 is a novel orally bioavailable small molecule that binds to hemoglobin and produces a concentration‐dependent left shift of the oxygen–hemoglobin dissociation curve with subsequent increase in hemoglobin–oxygen affinity and arterial oxygen loading. To assess whether pharmacological modification of hemoglobin–oxygen affinity could ameliorate hypoxemia associated with lung fibrosis, we evaluated GBT1118 in a bleomycin‐induced mouse model of hypoxemia and fibrosis. After pulmonary fibrosis and hypoxemia were induced, GBT1118 was administered for eight consecutive days. Hypoxemia was determined by monitoring arterial oxygen saturation, while the severity of pulmonary fibrosis was assessed by histopathological evaluation and determination of collagen and leukocyte levels in bronchoalveolar lavage fluid. We found that hemoglobin modification by GBT1118 had strong antihypoxemic therapeutic effects with improved arterial oxygen saturation to near normal level. Moreover, GBT1118 treatment significantly attenuated bleomycin‐induced lung fibrosis, collagen accumulation, body weight loss, and leukocyte infiltration. This study is the first to suggest the beneficial effects of hemoglobin modification in fibrotic lungs and offers a promising and novel therapeutic strategy for the treatment of hypoxemia associated with chronic fibrotic lung disorders in human, including IPF.

Factors affecting dyspnea after the 6-minute walk test in idiopathic pulmonary fibrosis patients presenting with exercise-induced hypoxemia

[Purpose] The current study aimed to investigate factors affecting dyspnea after the 6-minute walk test (6MWT) in idiopathic pulmonary fibrosis (IPF) patients presenting with hypoxemia. [Subjects and Methods] The subjects were IPF out-patients with stable symptoms whose percutaneous arterial oxygen saturation fell to 88% during the 6MWT test. Quadriceps force, 6-minute walk distance (6MWD), dyspnea after the 6MWT, and leg fatigue (LF) were evaluated as exercise-related variables. [Results] The subjects were 14 patients (mean age 73.6 ± 6.3 years) classed based on the modified Medical Research Council dyspnea scale as 0 for 2 patients, 1 for 6 patients, and 2 for 6 patients, indicating that the patients were comparatively mild cases. Mean 6MWD was 408.9 ± 102.4 m, and dyspnea after the 6MWT and LF were 3.0 ± 1.4 and 1.5 ± 1.5, respectively. Dyspnea after the 6MWT was correlated with vital capacity (VC), forced vital capacity, and LF. Stepwise multiple regression analysis identified VC and LF as factors significantly affecting dyspnea after the 6MWT. [Conclusion] The results of this study demonstrated that it is necessary to evaluate both pulmonary function and LF in IPF patients presenting with exercise-induced hypoxemia and exertional dyspnea.

Daily physical activity affects exercise capacity in patients with idiopathic pulmonary fibrosis

[Purpose] The aim of this study was to determine which factors, including pulmonary, physical, and mental functions; dyspnea; and daily physical activity (PA) affect the 6-minute walk distance (6MWD) in IPF patients. [Subjects and Methods] The pulmonary, physical, and mental functions; dyspnea; PA; and 6MWD were assessed in 38 outpatients with IPF. PA was represented by the mean number of steps per day. [Results] The mean 6MWD was 443.8 m (SD, 98.5), and the mean number of steps per day showing PA was 5148.4 (SD, 3295.7). The 6MWD was correlated with age, base dyspnea index, vital capacity (VC), diffusion capacity of carbon monoxide, quadriceps force (QF), dyspnea during the 6-minute walk test, and PA. Stepwise multiple regression analysis revealed that VC (β=0.382), QF (β=0.272), and PA (β=0.574) were contributing factors of the 6MWD. [Conclusion] In patients with IPF, PA has a greater effect on the 6MWD than VC and QF. The evaluation of daily PA, in addition to physiological and muscle functions, is important in patients with IPF.

Pulmonary Hemodynamics and Six-Minute Walk Test Outcomes in Patients with Interstitial Lung Disease

Background. Six-minute walk test (6MWT) has 3 measurement outcomes, which are walk distance, desaturation, and symptom. The aim of this study was to examine whether routinely measured right-heart catheter (RHC) data correlate with 6MWT outcomes in patients with interstitial lung disease (ILD). Methods. Between June 2010 and December 2012, consecutive patients with ILD who underwent evaluation, including pulmonary function test, hemodynamic studies with right-heart catheter, and 6MWT as routine general practice, were recruited. Correlates of 3 outcomes of 6MWT were examined to reveal significant predictors. Results. Forty-six patients consisting of 20 with idiopathic pulmonary fibrosis, 14 with collagen vascular disease associated ILD, and 12 with other idiopathic interstitial pneumonia were recruited (mean % predicted FVC: 76.7 ± 17.1%). Several physiological variables, including mean pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR), were correlated with each 6MWT outcome. Stepwise multivariate regression analyses showed that % predicted FVC and % predicted DLco were independent predictors of walk distance (r² = 0.35, p = 0.0002). For SpO₂ at the end of 6MWT, % predicted DLco and PVR were selected as independent predictors (r² = 0.46, p < 0.0001). For dyspnea at the end of 6MWT, % predicted DLco was only one predictor (r² = 0.18, p = 0.005). Conclusion. Mean PAP had little impact on 6MWT outcomes in ILD patients who were nonselectively recruited, although PVR was one of predictors of desaturation.

Opioids: an unexplored option for treatment of dyspnea in IPF

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is the most common among the idiopathic interstitial pneumonias and has the worst prognosis, with a median survival of 3-5 years. The most common symptom in IPF is dyspnea, impacting on the patient's quality of life and life expectancy. Morphine in the treatment of dyspnea has been investigated but with conflicting results. This review aims to clarify the role of opioids in the treatment of dyspnea in patients with IPF.

METHODS

A literature search was performed using the MeSH and PubMed databases. As only very few studies included patients with IPF, studies conducted primarily with patients with chronic obstructive pulmonary disease were also included. In total, 14 articles were found.

RESULTS

Seven studies reported use of systemic morphine and seven studies of inhaled morphine. Five of the seven studies investigating systemic administration detected an improvement in either dyspnea or exercise capacity, whereas no beneficial effect on dyspnea was detected in any study using inhaled morphine. No severe adverse effects such as respiratory depression were reported in any study, although constipation was reported as a notable adverse effect.

CONCLUSIONS

Results were inconsistent, but in some studies systemic morphine administration showed a significant improvement in the dyspnea score on a visual analog scale without observation of severe side effects. Nebulized morphine had no effect on dyspnea.

Supplemental oxygen users with pulmonary fibrosis perceive greater dyspnea than oxygen non-users

Background

Exertional dyspnea is a hallmark symptom of fibrosing interstitial lung disease (fILD), and oxygen (O₂) desaturation is common among patients with fILD. Supplemental O₂ is prescribed to maintain normoxia and alleviate dyspnea. We sought to better understand the associations between O₂ and dyspnea in fILD during the 6-min walk test (6MWT).

Methods

1326 fILD patients compose the sample group. Borg dyspnea and other 6MWT variables were compared between subjects who performed the test without (non-users) versus with O₂ (users).

Results

There were 812 users and 514 non-users; users were older, more likely to have smoked, had greater body mass index, and had more severe fILD. Despite a similar 6-min SpO₂, users perceived greater dyspnea than non-users (Borg 3.9 ± 2.0 vs 2.9 ± 1.7, p < 0.0001). Whether subjects became hypoxemic (6-min SpO₂ < 89 %) or not during the walk, the results were the same: users perceived greater dyspnea than non-users (hypoxemic: users 3.5 ± 2.1 vs non-users 2.7 ± 1.8, p < 0.0001; non-hypoxemic: users 3.4 ± 1.9 vs non-users 2.4 ± 1.6, p < 0.0001). Among subjects who did not desaturate (SpO₂ drop < 4 %), users walked a shorter distance (944.9 ± 367.0 vs 1385.3 ± 322.4 feet, p < 0.0001) but perceived greater dyspnea than non-users (3.3 ± 1.6 vs 2.3 ± 1.7, p = 0.005). No combination of potentially influential predictor variables entered in multivariate models explained more than 11 % of the variance in dyspnea ratings.

Conclusion

Dyspnea is a complex perception, and in patients with fILD, O₂ may lessen, but does not resolve, it. Further research is needed to clarify why fILD patients who use O₂ perceive greater levels of dyspnea with activity than O₂ non-users.

An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease

Field walking tests are commonly employed to evaluate exercise capacity, assess prognosis and evaluate treatment response in chronic respiratory diseases. In recent years, there has been a wealth of new literature pertinent to the conduct of the 6-min walk test (6MWT), and a growing evidence base describing the incremental and endurance shuttle walk tests (ISWT and ESWT, respectively). The aim of this document is to describe the standard operating procedures for the 6MWT, ISWT and ESWT, which can be consistently employed by clinicians and researchers. The Technical Standard was developed by a multidisciplinary and international group of clinicians and researchers with expertise in the application of field walking tests. The procedures are underpinned by a concurrent systematic review of literature relevant to measurement properties and test conduct in adults with chronic respiratory disease. Current data confirm that the 6MWT, ISWT and ESWT are valid, reliable and responsive to change with some interventions. However, results are sensitive to small changes in methodology. It is important that two tests are conducted for the 6MWT and ISWT. This Technical Standard for field walking tests reflects current evidence regarding procedures that should be used to achieve robust results.

An official systematic review of the European Respiratory Society/American Thoracic Society: measurement properties of field walking tests in chronic respiratory disease

This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease.

Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013.

The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r=0.59–0.93) and physical activity (r=0.40–0.85) than with respiratory function (r=0.10–0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training.

The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.

Long-term results and predictors of survival after surgical resection of patients with lung cancer and interstitial lung diseases

OBJECTIVES

Patients with interstitial lung diseases have a poor prognosis and are at increased risk of developing lung cancer. We evaluated the survival and predictors of survival after surgical resection in lung cancers in patients with interstitial lung diseases.

METHODS

We retrospectively analyzed data from 1763 patients with non-small cell lung cancer with a clinical diagnosis of interstitial lung disease who underwent pulmonary resection between 2000 and 2009 at 61 Japanese institutions.

RESULTS

Male patients (90.4%) and smokers (93.8%) were in the majority. The overall 5-year survival was 40%. The 5-year survivals were 59%, 42%, 43%, 29%, 25%, 17%, and 16% for patients with stage Ia, Ib, IIa, IIb, IIIa, IIIb, and IV, respectively. Patients with stage IA had a 5-year survival of 33.2%, 61.0%, and 68.4% in the wedge resection, segmentectomy, and lobectomy groups, respectively (log-rank test, P = .0038). The leading cause of death was cancer recurrence (50.2%), followed by respiratory failure (26.8%). Wedge resection reduced mortality due to respiratory failure when compared with that of lobectomy (P = .022). Multivariable analysis revealed that the type of surgical procedure, predicted percent vital capacity, and tumor locations were independent predictors for survival. The 5-year survival was 20% for patients with stage Ia with a predicted percent vital capacity of 80% or less, and 64.3% for patients with a predicted percent vital capacity greater than 80% (log-rank test, P < .0001).

CONCLUSIONS

In these patients, there are competing risks of death. Wedge resection reduced death caused by respiratory failure but resulted in poorer long-term prognosis than lobectomy. For patients with poor predictors of survival, such as predicted percent vital capacity of 80% or less, surgical resection should be limited.

Dyspnea in idiopathic pulmonary fibrosis: a systematic review

CONTEXT

Little is known about the treatment and correlates of dyspnea in idiopathic pulmonary fibrosis (IPF).

OBJECTIVES

The objective of this systematic review was to summarize the literature regarding the treatment and correlates of dyspnea in IPF.

METHODS

MEDLINE, EMBASE, and all Evidence-Based Medicine Reviews were searched for publications that evaluated treatment or correlates of dyspnea in IPF. Reference lists and recent review articles also were searched.

RESULTS

The heterogeneity of included studies did not permit meta-analysis. Dyspnea improved in studies of sildenafil, pulmonary rehabilitation, and prednisone with colchicine. Additional studies of these three treatments, however, found discordant results. One study suggested that assisted ventilation delivered by facemask improved exertional dyspnea. Oxygen and opioids improve dyspnea in other chronic lung diseases, but data in IPF are limited. Correlates of dyspnea included functional and physiological measures and comorbid diseases.

CONCLUSION

Sildenafil and pulmonary rehabilitation should be considered as potential therapies for dyspnea in selected patients with IPF. Supplemental oxygen and opioids may be additional potential therapies; however, the evidence supporting their use is weak. Additional research should focus on the management of functional status and comorbidities as potential treatments for dyspnea.

Benefits of pulmonary rehabilitation in idiopathic pulmonary fibrosis

BACKGROUND

Information on the benefits of pulmonary rehabilitation (PR) in patients with idiopathic pulmonary fibrosis (IPF) is growing, but PR's effects on certain important outcomes is lacking.

METHODS

We conducted a pilot study of PR in IPF and analyzed changes in functional capacity, fatigue, anxiety, depression, sleep, and health status from baseline to after completion of a standard, 6-week PR program.

RESULTS

Six-min walk distance improved a mean ± standard error 202 ± 135 feet (P = .01) from baseline. Fatigue Severity Scale score also improved significantly, declining an average 1.5 ± 0.5 points from baseline. There were trends toward improvement in anxiety, depression, and health status.

CONCLUSIONS

PR improves functional capacity and fatigue in patients with IPF. (Clinical Trials.gov registration NCT00692796.)

MRC chronic Dyspnea Scale: Relationships with cardiopulmonary exercise testing and 6-minute walk test in idiopathic pulmonary fibrosis patients: a prospective study

Background

Exertional dyspnea is the most prominent and disabling feature in idiopathic pulmonary fibrosis (IPF). The Medical Research Chronic (MRC) chronic dyspnea score as well as physiological measurements obtained during cardiopulmonary exercise testing (CPET) and the 6-minute walk test (6MWT) are shown to provide information on the severity and survival of disease.

Methods

We prospectively recruited IPF patients and examined the relationship between the MRC score and either CPET or 6MWT parameters known to reflect physiologic derangements limiting exercise capacity in IPF patients

Results

Twenty-five patients with IPF were included in the study. Significant correlations were found between the MRC score and the distance (r = -.781, p < 0.001), the SPO₂ at the initiation and the end (r = -.542, p = 0.005 and r = -.713, p < 0.001 respectively) and the desaturation index (r = .634, p = 0.001) for the 6MWT; the MRC score and VO₂ peak/kg (r = -.731, p < 0.001), SPO₂ at peak exercise (r = -. 682, p < 0.001), VE/VCO₂ slope (r = .731, p < 0.001), VE/VCO₂ at AT (r = .630, p = 0.002) and the Borg scale at peak exercise (r = .50, p = 0.01) for the CPET. In multiple logistic regression analysis, the only variable independently related to the MRC is the distance walked at the 6MWT.

Conclusion

In this population of IPF patients a good correlation was found between the MRC chronic dyspnoea score and physiological parameters obtained during maximal and submaximal exercise testing known to reflect ventilatory impairment and exercise limitation as well as disease severity and survival. This finding is described for the first time in the literature in this group of patients as far as we know and could explain why a simple chronic dyspnea score provides reliable prognostic information on IPF.

The 6 minute walk in idiopathic pulmonary fibrosis: longitudinal changes and minimum important difference

RATIONALE

The response characteristics of the 6 minute walk test (6MWT) in studies of idiopathic pulmonary fibrosis (IPF) are only poorly understood, and the change in walk distance that constitutes the minimum important difference (MID) over time is unknown.

OBJECTIVES

To examine changes over time in distance walked (ie, 6MWD) during the 6MWT and to estimate the change in distance that constitutes the MID in patients with IPF.

METHODS

Data from a recently completed trial that included subjects with IPF who completed the 6MWT, Saint George's Respiratory Questionnaire (SGRQ) and forced vital capacity (FVC) at 6 and 12 months were used to examine longitudinal changes in 6MWD. Both anchor- and distribution-based approaches as well as linear regression analyses were used to determine the MID for 6MWD. The SGRQ Total score and FVC were used as clinical anchors.

MAIN RESULTS

Among 123 subjects alive and able to complete the 6MWT at both follow-up time points, 6MWD did not change significantly over time (378.1 m at baseline vs 376.8 m at 6 months vs 361.3 m at 12 months, p=0.5). The point estimate for the 6MWD MID was 28 m with a range of 10.8-58.5 m.

CONCLUSION

In a group of patients with IPF with moderate physiological impairment, for those alive and able to complete a 6MWT, 6MWD does not change over 12 months. At the population level, the MID for 6MWD appears to be approximately 28 m. Further investigation using other anchors and derivation methods is required to refine estimates of the MID for 6MWD in this patient population.

Review series: Rehabilitation in non COPD: Mechanisms of exercise limitation and pulmonary rehabilitation for patients with pulmonary fibrosis/restrictive lung disease

The standard of care in the treatment of chronic lung disease includes pulmonary rehabilitation (PR). While evidence of the effectiveness of PR in chronic obstructive lung disease (COPD) is robust, that for pulmonary fibrosis and other non-fibrotic restrictive lung diseases is less extensive. However, PR has been shown to improve functional exercise capacity and health-related quality of life in non-COPD patients, primarily those with interstitial lung diseases. This review examines mechanisms of exercise limitation in non-COPD patients and discusses how they might affect both the application of and outcome measures of PR. We also review the assessment of exercise performance, dyspnea, and quality of life as well as special protocols, safety considerations, and special techniques in PR as applied to patients with pulmonary fibrosis or restrictive lung disease. At present, there are no evidence-based guidelines for PR in non-COPD patients whereas PR is firmly recommended in COPD management. More research is needed to strengthen the evidence for the use of PR in non-COPD patients. Meanwhile, the available data, summarized in this review, support the inclusion of PR in the management of all patients with chronic lung disease including pulmonary fibrosis and restrictive lung disease.

Spectrum of fibrosing diffuse parenchymal lung disease

The interstitial lung diseases are a heterogeneous group of disorders characterized by inflammation and/or fibrosis of the pulmonary interstitium. In 2002, the American Thoracic Society and the European Respiratory Society revised the classification of interstitial lung diseases and introduced the term diffuse parenchymal lung disease. The idiopathic interstitial pneumonias are a subtype of diffuse parenchymal lung disease. The idiopathic interstitial pneumonias are subdivided into usual interstitial pneumonia (with its clinical counterpart idiopathic interstitial pneumonia), nonspecific interstitial pneumonia, cryptogenic organizing pneumonia, acute interstitial pneumonia, desquamative interstitial pneumonia, respiratory bronchiolitis interstitial lung disease, and lymphocytic pneumonia. Sarcoidosis and hypersensitivity pneumonitis are the 2 most common granulomatous diffuse parenchymal lung diseases. Rheumatoid arthritis, systemic sclerosis, and dermatomyositis/polymyositis (causing antisynthetase syndrome) are diffuse parenchymal lung diseases of known association because these conditions are associated with connective tissue disease. Hermansky-Pudlak syndrome is a rare genetic diffuse parenchymal lung disease characterized by the clinical triad of pulmonary disease, oculocutaneous albinism, and bleeding diathesis. This review provides an overview of the chronic fibrosing diffuse parenchymal lung diseases. Its primary objective is to illuminate the clinical challenges encountered by clinicians who manage the diffuse parenchymal lung diseases regularly and to offer potential solutions to those challenges. Treatment for the diffuse parenchymal lung diseases is limited, and for many patients with end-stage disease, lung transplantation remains the best option. Although much has been learned about the diffuse parenchymal lung diseases during the past decade, research in these diseases is urgently needed.

Pulmonary hypertension in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is an untreatable diffuse parenchymal lung disease with a median survival of < 3 years. Pulmonary hypertension (PH) is frequently seen in patients with IPF and is commonly attributed to hypoxic vasoconstriction and capillary destruction. Pathology findings include endothelial proliferation and medial hypertrophy that exceed those expected in the setting of hypoxia. Noninvasive evaluation has limited sensitivity and specificity for the diagnosis of PH in IPF; therefore, right-heart catheterization remains the "gold standard" diagnostic test. PH in patients with IPF is associated with decreased exercise capacity and worse survival. Given the grave consequences of this condition, treatment of PH could improve functional outcomes and survival. However, possible treatments such as long-term supplemental oxygen and targeted vascular therapy are either unstudied or remain unproven.