Prognostic significance of six-minute walk test in non-group 1 pulmonary hypertension

A modified six-minute walk test (6MWT) for low-resource settings-a cross-sectional study

BACKGROUND

The 6 min walk test (6MWT) is a validated tool used to assess functional capacity in a variety of patient populations. Space constraints often limit the practicality of the 6MWT according to the standard (2002) American Thoracic Society protocol, and therefore, adaptations to this protocol are common with potential implications for research and clinical practice. Furthermore, such implications for research and clinical practice may be augmented in low-resourced settings.

OBJECTIVES

To determine the agreement between the 6 min walk distance (6MWD) achieved on the standard 30 m (6MWT₃₀), and a straight 10 m (6MWT₁₀), or 10 m figure-of-eight (6MWT_F8) configuration, respectively.

METHODS

A cross-sectional study was conducted in a socioeconomic challenged community. A heterogeneous sample of adults (n = 27) with non-communicable disease were randomized into performing the 6MWT₁₀ (n = 15) or 6MWT_F8 (n = 12), in addition to the standard 6MWT₃₀. Pairwise comparison and concordance correlation coefficients were used to assess agreement.

RESULTS

The mean (SD) 6MWD₃₀ was 437(42) meters, while the mean 6MWD₁₀ was 371(57). The mean difference (SE; p-value) between the 6MWD₃₀ and 6MWD₁₀ was 67 m (8.6; p .01). The mean 6MWD₃₀ was 424(67) meters, while the mean 6MWD_F8 was 347(58). The mean difference between the 6MWD₃₀ and 6MWD_F8 was 77 m (6.0; p .01). Moderate concordance was found between the 6MWT₃₀ and 6MWT_F8 or 6MWD₁₀, respectively.

CONCLUSIONS

The present data suggest that, independent of configuration, using a shorter pathway significantly reduced the 6MWD. Low-resource settings may benefit from contemporary measures of functional capacity more conducive to resource constraints, or standardization of the test when used in such settings.

The incremental shuttle walk test predicts mortality in non-group 1 pulmonary hypertension: results from the ASPIRE Registry

Pulmonary hypertension (PH) is classified into five groups based on disease etiology but there is only limited information on the prognostic value of exercise testing in non-group 1 PH. In group 1 PH, the incremental shuttle walking test (ISWT) distance has been shown to correlate with pulmonary hemodynamics and predict survival without a ceiling effect. This study assessed the ISWT in non-group 1 PH. Data were retrieved from the ASPIRE Registry (Assessing the Spectrum of Pulmonary hypertension Identified at a REferral centre) for consecutive patients diagnosed with PH. Patients were required to have been systematically assessed as group 2-5 PH and to have a baseline ISWT within three months of cardiac catheterization. Patients were stratified according to incremental shuttle walk test distance (ISWD) and ISWT distance percent predicted (ISWD%pred). A total of 479 patients with non-group 1 PH were identified. ISWD and ISWD%pred correlated significantly with symptoms and hemodynamic severity. ISWD and ISWD%pred predicted survival with no ceiling effect. The test was prognostic in groups 2, 3, and 4. ISWD and ISWD%pred and change in ISWD and ISWD%pred at one year were all significant predictors of outcome. In patients with non-group 1 PH the ISWT is a simple non-invasive test that is easy to perform, is predictive of survival at baseline and follow-up, reflects change, and can be used in the assessment of PH of any etiology.

Red blood cell distribution width as a potential predictor of survival of pulmonary arterial hypertension associated with primary Sjogren's syndrome: a retrospective cohort study

Pulmonary arterial hypertension (PAH) is a severe complication and leading cause of mortality in patients with primary Sjogren's syndrome (pSS). This study was to investigate the overall survival rates and the utility of red blood cell distribution width (RDW) as a potential prognostic factor of pSS-PAH. This cohort study retrospectively enrolled 55 patients with pSS-PAH who were followed up at the Department of Rheumatology of Peking Union Medical College Hospital (PUMCH) between August 2007 and May 2017. The patients were stratified according to the level of RDW (≤ 15.0 and > 15.0%). Baseline demographics, laboratory results, pulmonary function conditions, hemodynamic assessments, and treatment regimens were analyzed. Cox proportional hazards regression analysis was used to identify whether RDW level is a factor related to adverse outcome. A total of 55 patients were recruited, with an average age of 38.9 ± 9.3 years. Fifty-four were female (98.2%), and the average duration at the time of PAH diagnosis was 25.5 ± 33.2 months. Higher RDW levels were found in patients who deceased in follow-up (13.8 ± 2.6 vs 16.5 ± 1.6%, p = 0.003) and with higher NYHA classes (13.8 ± 1.8 vs 16.5 ± 2.9%, p < 0.001). Patients with RDW > 15% had a significantly worse overall survival than patients with RDW ≤ 15% (3-year survival rate 59.5 vs. 88.7% log-rank p = 0.015). Cox regression analysis identified RDW > 15% as a prognostic factor for adverse outcome (HR 1.786, 95% CI 1.137-2.803, p = 0.012). RDW can serve as a potential negative prognostic factor of pSS-PAH.

Minimal clinically important difference for the 6-min walk test: literature review and application to Morquio A syndrome

Morquio A syndrome is an ultra-rare, inherited lysosomal storage disorder associated with progressive, multi-systemic clinical impairments, causing gradual loss of functional capacity and endurance, impaired quality of life, and early mortality. Studies in Morquio A patients have used the 6-min walk test (6MWT) to assess functionality and endurance and to evaluate disease progression or efficacy of treatment. The objective of the present study was to review minimal clinically important differences (MCIDs) for the 6MWT reported for disease states that widely use the 6MWT to evaluate clinical benefit and to discuss the results in view of the challenges in estimating MCID for ultra-rare diseases, using the case of elosulfase alfa in Morquio A patients. A systematic literature search was performed using Embase and Medline to identify studies specifically estimating the MCID using either anchor-based or distribution-based methods. A total of 19 publications on 17 studies were identified; none of these included patients with Morquio A syndrome or the wider disease category of lysosomal storage disorders. Therefore, the MCIDs determined by studies in patients with respiratory, cardiovascular, or musculoskeletal disease were compared to changes in the 6MWT seen in Morquio A patients in the pivotal phase 3 clinical trial of elosulfase alfa enzyme replacement therapy. The literature review showed a mean MCID for the 6MWT of 7% change (range 3–15%) in studies using anchor-based methods and a 9% change (range 4–16%) using distribution-based methods. Results of the elosulfase alfa clinical trial and its extension showed a placebo-adjusted 14.9% improvement in the 6MWT from baseline at week 24, which was greater than the mean MCID based on the results of the systematic literature review. After 2 years, 6MWT distance increased by a mean of 20.7% from baseline in a modified per-protocol population, versus a reduction of 6.9% in comparable untreated patients from the MorCAP natural history study over the same period. Although further research is required to establish the MCID of the 6MWT in Morquio A patients, the presented data provide further evidence for the positive effect of elosulfase alfa in this patient population.

End-of-life prognostic indicators in patients with COPD: part 2

In the UK, chronic respiratory diseases cause 13% of adult disability. The major chronic respiratory disease is chronic obstructive pulmonary disease (COPD), a condition involving chronic airway inflammation that causes airflow obstruction and destruction of lung tissue. This leads to a progressive loss of respiratory membrane, which accounts for the clinical manifestation of COPD, which is difficulty maintaining sufficient gas exchange to meet metabolic demands. The primary cause is smoking, with the vast majority of COPD patients having a past or present history of smoking. However, exposure to industrial pollutants is also a contributing factor, as is a rare genetic predisposition to developing COPD.

End-of-life prognostic indicators in patients with COPD: Part 1

In the UK, chronic respiratory diseases cause 13% of adult disability. The major chronic respiratory disease is chronic obstructive pulmonary disease (COPD), a condition involving chronic airway inflammation that causes airflow obstruction and destruction of lung tissue. This leads to a progressive loss of respiratory membrane, which accounts for the clinical manifestation of COPD, which is difficulty maintaining sufficient gas exchange to meet metabolic demands. The primary cause is smoking, with the vast majority of COPD patients having a past or present history of smoking. However exposure to industrial pollutants is also a contributing factor, as is a rare genetic predisposition to developing COPD.

Statins Have No Additional Benefit for Pulmonary Hypertension: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

We performed a meta-analysis to explore the effects of adding statins to standard treatment on adult patients of pulmonary hypertension (PH).

METHODS

A systematic search up to December, 2015 of Medline, EMBASE, Cochrane Database of Systematic reviews and Cochrane Central Register of Controlled Trials was performed to identify randomized controlled trials with PH patients treated with statins.

RESULTS

Five studies involving 425 patients were included into this meta-analysis. The results of our analysis showed that the statins can't significantly increase 6-minute walking distance (6MWD, mean difference [MD] = -0.33 [CI: -18.25 to 17.59]), decrease the BORG dyspnea score (MD = -0.72 [CI: -2.28 to 0.85]), the clinical worsening risk (11% in statins vs. 10.1% in controls, Risk ratio = 1.06 [CI: 0.61, 1.83]), or the systolic pulmonary arterial pressure (SPAP) (MD = -0.72 [CI: -2.28 to 0.85]). Subgroup analysis for PH due to COPD or non-COPD also showed no significance.

CONCLUSIONS

Statins have no additional beneficial effect on standard therapy for PH, but the results from subgroup of PH due to COPD seem intriguing and further study with larger sample size and longer follow-up is suggested.

Serum Bilirubin and 6-min Walk Distance as Prognostic Predictors for Inoperable Chronic Thromboembolic Pulmonary Hypertension: A Prospective Cohort Study

Background:

Inoperable chronic thromboembolic pulmonary hypertension (CTEPH) is a severe clinical syndrome characterized by right cardiac failure and possibly subsequent liver dysfunction. However, whether serum markers of liver dysfunction can predict prognosis in inoperable CTEPH patients has not been determined. Our study aimed to evaluate the potential role of liver function markers (such as serum levels of transaminase, bilirubin, and gamma-glutamyl transpeptidase [GGT]) combined with 6-min walk test in the prediction of prognosis in patients with inoperable CTEPH.

Methods:

From June 2005 to May 2013, 77 consecutive patients with inoperable CTEPH without confounding co-morbidities were recruited for this prospective cohort study. Baseline clinical characteristics and 6-min walk distance (6MWD) results were collected. Serum biomarkers of liver function, including levels of aspartate aminotransferase, alanine aminotransferase, GGT, uric acid, and serum bilirubin, were also determined at enrollment. All-cause mortality was recorded during the follow-up period.

Results:

During the follow-up, 22 patients (29%) died. Cox regression analyses demonstrated that increased serum concentration of total bilirubin (hazard ratio [HR] = 7.755, P < 0.001), elevated N-terminal of the prohormone brain natriuretic peptide (HR = 1.001, P = 0.001), decreased 6MWD (HR = 0.990, P < 0.001), increased central venous pressure (HR = 1.074, P = 0.040), and higher pulmonary vascular resistance (HR = 1.001, P = 0.018) were associated with an increased risk of mortality. Serum concentrations of total bilirubin (HR = 4.755, P = 0.007) and 6MWD (HR = 0.994, P = 0.017) were independent prognostic predictors for CTEPH patients. Patients with hyperbilirubinemia (≥23.7 μmol/L) had markedly worse survival than those with normobilirubinemia.

Conclusion:

Elevated serum bilirubin and decreased 6MWD are potential predictors for poor prognosis in inoperable CTEPH.

Exercise training improves physical fitness in patients with pulmonary arterial hypertension: a systematic review and meta-analysis of controlled trials

BACKGROUND

Pulmonary arterial hypertension (PAH) is a progressive disorder characterized by hypertension in the pulmonary arteries. PAH leads to symptoms such as shortness of breath, dizziness, leg edema and chest pain, impacting heavily on quality of life. The aim of this systematic review and meta-analysis was to determine the effect of exercise training to improve physical fitness and functionality in patients with PAH.

METHODS

A search was conducted for controlled trials using the databases Medline, Embase, SPORT Discus and Cochrane Central Register of Controlled Trials. Studies were included if at least 80% of the participants presented with group 1 PAH and if the intervention consisted of an exercise training program of at least 3 weeks duration. Data were extracted on study quality, participant and exercise intervention characteristics, and outcomes. Data were pooled by the generic inverse variance method using random effect models and were expressed as weighted means and 95% confidence intervals (CI).

RESULTS

Of 110 identified abstracts, 5 studies with 106 patients (exercise: 53; control: 53; mean age 49.7 years) were included. Disease severity ranged from mild to severe; 96 patients suffered from PAH, 10 patients had chronic thromboembolic pulmonary hypertension. Exercise training led to an increase in 6 minute walk distance (72.5 m; 95% CI 46.0 m to 99.1 m; p < 0.0001) and peak oxygen uptake (2.16 mL/kg/min; 95% CI 2.16 to 3.93; p = 0.02). No severe adverse events during exercise were reported.

CONCLUSIONS

Our findings suggest that an exercise training program positively influences exercise tolerance and functional capacity in patients with PAH.

Pulmonary hypertension and right heart dysfunction in chronic lung disease

Group 3 pulmonary hypertension (PH) is a common complication of chronic lung disease (CLD), including chronic obstructive pulmonary disease (COPD), interstitial lung disease, and sleep-disordered breathing. Development of PH is associated with poor prognosis and may progress to right heart failure, however, in the majority of the patients with CLD, PH is mild to moderate and only a small number of patients develop severe PH. The pathophysiology of PH in CLD is multifactorial and includes hypoxic pulmonary vasoconstriction, pulmonary vascular remodeling, small vessel destruction, and fibrosis. The effects of PH on the right ventricle (RV) range between early RV remodeling, hypertrophy, dilatation, and eventual failure with associated increased mortality. The golden standard for diagnosis of PH is right heart catheterization, however, evidence of PH can be appreciated on clinical examination, serology, radiological imaging, and Doppler echocardiography. Treatment of PH in CLD focuses on management of the underlying lung disorder and hypoxia. There is, however, limited evidence to suggest that PH-specific vasodilators such as phosphodiesterase-type 5 inhibitors, endothelin receptor antagonists, and prostanoids may have a role in the treatment of patients with CLD and moderate-to-severe PH.