Elsevier

American Heart Journal

Volume 163, Issue 1, January 2012, Pages 88-94.e3
American Heart Journal

Clinical Investigation
Outcomes, Health Policy, and Managed Care
Relationships between changes in patient-reported health status and functional capacity in outpatients with heart failure

https://doi.org/10.1016/j.ahj.2011.09.027Get rights and content

Background

Heart failure trials use a variety of measures of functional capacity and quality of life. Lack of formal assessments of the relationships between changes in multiple aspects of patient-reported health status and measures of functional capacity over time limits the ability to compare results across studies.

Methods

Using data from HF-ACTION (N = 2331), we used the Pearson correlation coefficients and predicted change scores from linear mixed-effects modeling to demonstrate the associations between changes in patient-reported health status measured with the EQ-5D visual analog scale and the Kansas City Cardiomyopathy Questionnaire (KCCQ) and changes in peak VO2 and 6-minute walk distance at 3 and 12 months. We examined a 5-point change in KCCQ within individuals to provide a framework for interpreting changes in these measures.

Results

After adjustment for baseline characteristics, correlations between changes in the visual analog scale and changes in peak VO2 and 6-minute walk distance ranged from 0.13 to 0.28, and correlations between changes in the KCCQ overall and subscale scores and changes in peak VO2 and 6-minute walk distance ranged from 0.18 to 0.34. A 5-point change in KCCQ was associated with a 2.50-mL kg−1 min−1 change in peak VO2 (95% CI 2.21-2.86) and a 112-m change in 6-minute walk distance (95% CI 96-134).

Conclusions

Changes in patient-reported health status are not highly correlated with changes in functional capacity. Our findings generally support the current practice of considering a 5-point change in the KCCQ within individuals to be clinically meaningful.

Section snippets

Methods

HF-ACTION was a multicenter, randomized controlled trial designed to test the long-term safety and efficacy of aerobic exercise training vs usual care in a large, multinational sample of patients with left ventricular dysfunction and heart failure.8 Enrollment criteria included left ventricular ejection fraction of 35% or less, New York Heart Association (NYHA) class II to IV heart failure, and ability and willingness to undergo exercise training. Patients were excluded if they were unable to

Results

Table I shows the baseline characteristics of the study population. Baseline characteristics did not differ by treatment group.18 Table II shows the visit-level missing data through 12 months of follow-up, accounting for patients who died or withdrew from the study.

Table III shows the Pearson correlation coefficients comparing changes in patient-reported health status and changes in the functional capacity measures at 3 and 12 months. After adjustment for baseline patient characteristics, there

Discussion

To our knowledge, ours is the first study to use longitudinal data to characterize relationships between changes in multiple aspects of patient-reported health status and changes in 2 commonly used functional measures of disease severity. The study population in HF-ACTION was large, relatively diverse, and balanced with respect to heart failure etiology, and the patients received evidence-based, guideline-supported therapy. We used a conservative approach to model these relationships and

Conclusions

Changes in patient-reported health status, as measured by the VAS and the KCCQ and its subscales, are not highly correlated with changes in functional capacity, including peak VO2 and 6-minute walk distance. According to the predominant model of patient outcomes,20 our findings do not alter the recommendation of considering a 5-point change in the KCCQ within individuals to be clinically meaningful.5 This information will help to inform researchers about study design and interpretation in heart

Disclosures

The authors are solely responsible for the design and conduct of this study, all study analyses, the drafting and editing of the manuscript, and its final contents. The content does not necessarily represent the official views of the National Heart, Lung, and Blood Institute or the National Institutes of Health. The relevant institutional review boards of the participating centers and the coordinating center approved the protocol. This work was supported by grants from the National Heart, Lung,

Acknowledgements

Stephen J. Ellis, PhD, Duke University, suggested consideration of alternative modeling approaches to estimate minimally important change. Damon M. Seils, MA, Duke University, assisted with the manuscript preparation. Dr Ellis and Mr Seils did not receive compensation for their assistance apart from their employment at the institution where the study was conducted.

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    Leslee J. Shaw, PhD served as guest editor for this article.

    Randomized controlled trial registration: clinicaltrials.gov identifier: NCT00047437.

    Funding/support: HF-ACTION was funded by grants 5U01HL063747, 5U01HL066461, 5U01HL068973, 5U01HL066501, 5U01HL066482, 5U01HL064250, 5U01HL066494, 5U01HL064257, 5U01HL066497, 5U01HL068980, 5U01HL064265, 5U01HL066491, and 5U01HL064264 from the National Heart, Lung, and Blood Institute and grants R37AG018915 and P60AG010484 from the National Institute on Aging.

    i

    For the HF-ACTION Investigators. See the online Appendix for a complete listing of the HF-ACTION Investigators.

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