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The need to move from 6-minute walk distance to outcome trials in pulmonary arterial hypertension.

ABSTRACT: Assessment of change in exercise capacity using the 6-min walk distance (6MWD) test has been the primary end-point in the majority of pulmonary arterial hypertension (PAH) clinical trials. The 6MWD has some advantages as an end-point in such studies. It is simple and inexpensive to perform, reproducible and validated. In short-term studies with small patient numbers, as is typical in a rare disease like PAH, using change from baseline in 6MWD as the primary outcome measure demonstrated statistically significant differences between placebo and study drugs, leading to their approval. However, there have been increasing calls for clinical trials to employ primary end-points that reflect long-term disease progression and morbidity. While the 6MWD was initially considered to be a potentially reliable surrogate for disease progression in PAH, there is increasing evidence that this is not necessarily the case. Given this, there is a need to re-examine the role of 6MWD in PAH trials, and to evaluate the evidence supporting whether there is a need to move from 6MWD to more robust measures of clinical outcomes, such as morbidity and mortality. However, in the clinic the 6MWD test, alongside symptoms, haemodynamics and biomarkers, remains a useful tool in the assessment and management of PAH patients.

SUBMITTER: Gaine S

PROVIDER: S-EPMC9639189 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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The need to move from 6-minute walk distance to outcome trials in pulmonary arterial hypertension.

Gaine Sean S Simonneau Gérald G

European respiratory review : an official journal of the European Respiratory Society 20131201 130

Assessment of change in exercise capacity using the 6-min walk distance (6MWD) test has been the primary end-point in the majority of pulmonary arterial hypertension (PAH) clinical trials. The 6MWD has some advantages as an end-point in such studies. It is simple and inexpensive to perform, reproducible and validated. In short-term studies with small patient numbers, as is typical in a rare disease like PAH, using change from baseline in 6MWD as the primary outcome measure demonstrated statistic ...[more]

PMID: 24293464

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Project description:BackgroundPatients with pulmonary arterial hypertension who achieve a six-minute walk distance of 380-440 m may have improved prognosis. Using the randomized controlled trial of macitentan in pulmonary arterial hypertension (SERAPHIN), the association between six-minute walk distance and long-term outcomes was explored.MethodsPatients with six-minute walk distance data at Month 6 were dichotomized as above or below the median six-minute walk distance (400 m) and assessed for future risk of pulmonary arterial hypertension-related death or hospitalization and all-cause death. Additionally, six-minute walk distance values at baseline, Month 6 and the change from baseline to Month 6 were categorized by quartiles. All associations were analyzed by the Kaplan-Meier method using a log-rank test and Cox regression models.ResultsPatients with a six-minute walk distance >400 m vs. ≤400 m at Month 6 have a reduced risk of pulmonary arterial hypertension-related death or hospitalization (hazard ratio 0.48; 95% confidence interval 0.33-0.69). The risk was also lower for patients with higher quartiles of six-minute walk distance at baseline or Month 6 (baseline: hazard ratio [Q4 (>430 m) vs. Q1 (≤300 m)] 0.23; 95% confidence interval 0.15-0.36; Month 6: hazard ratio [Q4 (>455 m) vs. Q1 (≤348 m)] 0.33; 95% confidence interval 0.19-0.55). In contrast, six-minute walk distance changes at Month 6 were not associated with the risk of pulmonary arterial hypertension-related death or hospitalization (p = 0.477). These findings were consistent when adjusted for known confounders. Similar results were observed for the risk of all-cause death up to end of study.ConclusionsPatients with pulmonary arterial hypertension walking >400 m had better long-term prognosis. Although changes in six-minute walk distance were not associated with long-term outcomes, assessing absolute six-minute walk distance values remains important in the clinical management of patients with pulmonary arterial hypertension.

Project description:BackgroundPulmonary arterial hypertension (PAH) is a chronic disease of the pulmonary vasculature that can lead to heart failure and premature death. Assessment of patients with PAH includes performing a 6-minute walk test (6MWT) in clinics. We developed a smartphone app to compute the walked distance (6MWD) indoors, by counting U-turns, and outdoors, by using satellite positioning.ObjectiveThe goal of the research was to assess (1) accuracy of the indoor 6MWTs in clinical settings, (2) validity and test-retest reliability of outdoor 6MWTs in the community, (3) compliance, usability, and acceptance of the app, and (4) feasibility of pulse oximetry during 6MWTs.MethodsWe tested the app on 30 PAH patients over 6 months. Patients were asked to perform 3 conventional 6MWTs in clinic while using the app in the indoor mode and one or more app-based 6MWTs in outdoor mode in the community per month.ResultsBland-Altman analysis of 70 pairs of conventional versus app-based indoor 6MWDs suggests that the app is sometimes inaccurate (14.6 m mean difference, lower and upper limit of agreement: -133.35 m to 162.55 m). The comparison of 69 pairs of conventional 6MWDs and community-based outdoor 6MWDs within 7 days shows that community tests are strongly related to those performed in clinic (correlation 0.89), but the interpretation of the distance should consider that differences above the clinically significant threshold are not uncommon. Analysis of 89 pairs of outdoor tests performed by the same patient within 7 days shows that community-based tests are repeatable (intraclass correlation 0.91, standard error of measurement 36.97 m, mean coefficient of variation 12.45%). Questionnaires and semistructured interviews indicate that the app is usable and well accepted, but motivation to use it could be affected if the data are not used for clinical decision, which may explain low compliance in 52% of our cohort. Analysis of pulse oximetry data indicates that conventional pulse oximeters are unreliable if used during a walk.ConclusionsApp-based outdoor 6MWTs in community settings are valid, repeatable, and well accepted by patients. More studies would be needed to assess the benefits of using the app in clinical practice.Trial registrationClinicalTrials.gov NCT04633538; https://clinicaltrials.gov/ct2/show/NCT04633538.

Dataset Information

The need to move from 6-minute walk distance to outcome trials in pulmonary arterial hypertension.

Publications

The need to move from 6-minute walk distance to outcome trials in pulmonary arterial hypertension.

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