Measurement properties of the Timed Up & Go test in patients with COPD

Abstract

We aimed to investigate the construct validity of the Timed Up & Go (TUG) test in chronic obstructive pulmonary disease (COPD), to identify characteristics related to an abnormal TUG time and to examine the responsiveness of the TUG to pulmonary rehabilitation (PR). TUG time was assessed before and after comprehensive PR in 500 COPD patients, and compared cross-sectionally in 100 non-COPD subjects. Physical health outcomes, mental health outcomes, symptom-related outcomes and multidimensional indices were assessed in COPD patients only. Good convergent and discriminant validity was demonstrated by fair-to-moderate correlation with physical health outcomes, symptom-related outcomes and multidimensional indices ( rs = 0.18-0.70) and by little correlation with mental health outcomes ( rs = 0.21-0.26). COPD patients had a worse TUG time than non-COPD subjects, demonstrating known-groups validity. A TUG time of 11.2 seconds had good sensitivity (0.75) and specificity (0.83) for identifying patients with a baseline 6-minute walk distance <350 m. TUG time improved after PR ( p < 0.0001) and a change of 0.9-1.4 seconds was identified as clinically important. The TUG is valid and responsive in COPD. An abnormal result is indicative of poor health outcomes. This simple test provides valuable information and can be adopted in clinical and research settings.

Keywords: Chronic obstructive pulmonary disease; outcome assessment (healthcare); rehabilitation.

Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.

Correlation between TUG time and 6MWD in COPD patients. COPD: chronic obstructive pulmonary disease; 6MWD: 6-minute walk distance; TUG: Timed Up & Go.

Figure 2.

TUG time in COPD patients and in non-COPD subjects. The horizontal bars represent median (interquartile range 25–75%). The dotted line corresponds to the 95th percentile in the sample of non-COPD subjects (i.e. 11 seconds), which represents the threshold adopted to identify an abnormal TUG time. TUG: Timed Up & Go; COPD: chronic obstructive pulmonary disease.

Figure 3.

TUG time before and after pulmonary rehabilitation in COPD patients. The horizontal bars represent mean (standard deviation). *p < 0.05. TUG: Timed Up & Go; COPD: chronic obstructive pulmonary disease; ES: effect size.