0
Original Research: Critical Care |

Construct Validity and Minimal Important Difference of 6-Minute Walk Distance in Survivors of Acute Respiratory Failure6-Min Walk Distance Validity in ARDS

Kitty S. Chan, PhD; Elizabeth R. Pfoh, PhD; Linda Denehy, PhD; Doug Elliott, PhD; Anne E. Holland, PhD; Victor D. Dinglas, MPH; Dale M. Needham, MD, PhD
Author and Funding Information

From the Department of Health Policy and Management (Drs Chan and Pfoh), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; Department of Physiotherapy (Dr Denehy), The University of Melbourne, Melbourne, VIC, Australia; Faculty of Health (Dr Elliott), University of Technology, Sydney, NSW, Australia; Department of Physiotherapy (Dr Holland), La Trobe University, Melbourne, VIC, Australia; Department of Physiotherapy (Dr Holland), Alfred Health, Melbourne, VIC, Australia; Institute for Breathing and Sleep (Dr Holland), Melbourne, VIC, Australia; and Outcomes After Critical Illness and Surgery (OACIS) Group (Mr Dinglas and Dr Needham), Division of Pulmonary and Critical Care Medicine (Mr Dinglas and Dr Needham), and Department of Physical Medicine and Rehabilitation (Dr Needham), Johns Hopkins University School of Medicine, Baltimore, MD.

CORRESPONDENCE TO: Kitty S. Chan, PhD, Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, 624 N Broadway, Hampton House #633, Baltimore, MD 21205-1901; e-mail: kchan10@jhu.edu


FUNDING/SUPPORT: This research was supported by the National Heart, Lung, and Blood Institute [R24HL111895, R01HL091760, R01HL091760-02S1, R01HL096504, and P050HL7399], the Johns Hopkins Institute for Clinical and Translational Research [UL1TR000424-06], the Albuterol to Treat Acute Lung Injury (ALTA), the Early vs Delayed Enteral Feeding to Treat People With Acute Lung Injury or Acute Respiratory Distress Syndrome (EDEN), and the Omega-3 Fatty Acid/Antioxidant Supplementation for Treating People With Acute Lung Injury or Acute Respiratory Distress Syndrome (OMEGA) trials [contracts for sites participating in this study: HSN268200536170C, HHSN268200536171C, HHSN268200536173C, HHSN268200536174C, HSN268200536175C, and HHSN268200536179C]. The Elliott trial was supported by the Australian National Health and Medical Research Council (NHMRC) [Grant 352407]. The Denehy trial was completed with funds from the NHMRC [Grant 454717], the Physiotherapy Research Foundation, the Austin Hospital Medical Research Foundation, and the Australian and New Zealand Intensive Care Society.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2015;147(5):1316-1326. doi:10.1378/chest.14-1808
Text Size: A A A
Published online

OBJECTIVE:  The 6-min walk distance (6MWD), a widely used test of functional capacity, has limited evidence of construct validity among patients surviving acute respiratory failure (ARF) and ARDS. The objective of this study was to examine construct validity and responsiveness and estimate minimal important difference (MID) for the 6MWD in patients surviving ARF/ARDS.

METHODS:  For this secondary data analysis of four international studies of adult patients surviving ARF/ARDS (N = 641), convergent and discriminant validity, known group validity, predictive validity, and responsiveness were assessed. MID was examined using anchor- and distribution-based approaches. Analyses were performed within studies and at various time points after hospital discharge to examine generalizability of findings.

RESULTS:  The 6MWD demonstrated good convergent and discriminant validity, with moderate to strong correlations with physical health measures (|r| = 0.36-0.76) and weaker correlations with mental health measures (|r| = 0.03-0.45). Known-groups validity was demonstrated by differences in 6MWD between groups with differing muscle strength and pulmonary function (all P < .01). Patients reporting improved function walked farther, supporting responsiveness. 6MWD also predicted multiple outcomes, including future mortality, hospitalization, and health-related quality of life. The 6MWD MID, a small but consistent patient-perceivable effect, was 20 to 30 m. Findings were similar for 6MWD % predicted, with an MID of 3% to 5%.

CONCLUSIONS:  In patients surviving ARF/ARDS, the 6MWD is a valid and responsive measure of functional capacity. The MID will facilitate planning and interpretation of future group comparison studies in this population.


Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Figures

Tables

References

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Find Similar Articles
CHEST Journal Articles
PubMed Articles
  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543