Conference: 2012 International PHA Conference and Scientific Sessions
Release Date: 06.22.2012
Presentation Type: Abstracts
Boyer A, Chakinala M, Zheng J.
Washington University School of Medicine, United States of America
BACKGROUND: The Six-Minute Walk Test (6MWT) is often used in PAH patients to risk stratify and judge treatment response. In a group of healthy individuals, Enright predicted 6MWD based on age, gender, and body mass index (BMI). Using Enright’s equation, we aimed to analyze treatment response in a cohort of PAH subjects by determining the change in pp6MWD.
METHODS: Retrospective chart review was performed of treatment-naive patients enrolled in the Washington University Pulmonary Hypertension Clinic between January 1, 2004 and January 31, 2010. Data was recorded from the baseline visit including anthropometric measurements, absolute 6MWD (obtained as per ATS guidelines), WHO functional classification, pulmonary function testing, and key measurements from transthoracic echocardiography and right heart catheterization (RHC). The Enright equation was applied to determine baseline pp6MWD. Treatment response was evaluated during a second visit at any time point between 6 and 12 months after pharmacotherapy was initiated.
RESULTS: Baseline characteristics (mean age 50 +/- 12, female 70%, WHO functional class III/IV 77%) and hemodynamic variables of the 64 subjects included in the analysis were consistent with WHO Group I Pulmonary Hypertension. Mean absolute 6MWD was 275 +/- 116 m and mean pp6MWD was 49.2 +/- 20.9%. After pharmacotherapy (mean duration 262 +/- 54 days), absolute 6MWD increased 84.3 +/- 111 m (p<.0001) and pp6MWD increased 14.7 +/- 19.9% (p<0.001). Comparing subgroups of idiopathic PAH (n=18) and connective tissue disease associated PAH (n=21), there were no significant differences in baseline pp6MWD (47.6 +/- 16.9% vs. 40.2 +/- 24.4%, p=0.29) or change in pp6MWD after treatment (15.5 +/- 23.5% vs. 22.3 +/- 18.3%, p=0.31). Change in functional classification mirrored change in both absolute 6MWD and pp6MWD.
CONCLUSIONS: Significant improvement in pp6MWD was observed in a PAH cohort after pharmacotherapy. Whether change in pp6MWD offers more discriminatory value than change in absolute 6MWD in judging treatment response requires further investigation.