Abstract
Background
Previous investigation of the relationship between physical performance and patient self-report physical function (PF) measures in intensive care unit (ICU) survivors have not been performed.
Objectives
To (1) analyze the extent to which other activity-based measures of physical performance may serve as proxies for the 6-min walk test (6MWT); (2) determine the extent to which the Short Form (SF) 36 domain of PF and physical component summary (PCS) score, reflect components of physical performance and (3) examine the relationship between demographic and ICU variables and the 6MWT.
Design
Cross-sectional data from two clinical trials.
Setting
Two acute care hospitals (Melbourne, Australia and Denver, USA).
Patients
A total of 177 survivors of ICU.
Measurements
Were evaluated at 3 months. Performance-based measures were: 6MWT, timed up and go test (TUG), the five times sit to stand test (5×STS), the Berg balance scale (BBS) and two self-report measures: the SF-36 PF domain and the PCS score.
Main results
6MWT showed excellent correlation with the TUG (rho = −0.79) and BBS (rho = 0.80); and good correlation with 5×STS (rho = −0.69) and SF-36 PF scores (rho = 0.69). 6MWT explained 54 and 33 % of variance in SF-36 PF and PCS scores respectively. No variables were clinically important in predicting 6MWT.
Conclusions
The 6MWT and TUG may both be acceptable measures of PF performance 3 months after ICU. Performance-based tests measure different constructs than self-report measures and choice of outcome variables should be aligned with study aims to ensure the most appropriate measure is used.
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Acknowledgments
The current research is funded by the National Institutes of Health (R01 NR011051 to MM) and National Health and Medical Research Council (APP454717).
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Take-home message: The 6-min walk test and the timed up and go showed excellent correlations in 177 ICU survivors; these tests may both be acceptable measures of physical function performance 3 months after ICU. The performance-based measures explained one third to one half of self-reported measures (SF-36 physical function and physical component summary scores). Performance-based tests may measure different constructs than self-report measures, and choice of outcome variables should be aligned with study aims to ensure that the most appropriate measure is used.
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Denehy, L., Nordon-Craft, A., Edbrooke, L. et al. Outcome measures report different aspects of patient function three months following critical care. Intensive Care Med 40, 1862–1869 (2014). https://doi.org/10.1007/s00134-014-3513-3
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DOI: https://doi.org/10.1007/s00134-014-3513-3