Introduction Well-established functional outcome measures in COPD include the 6-min walk test (6MW) and incremental shuttle walk test (ISW). However, these tests require space, repetition, and can be time-consuming. In the elderly population, gait speed alone has been shown to be a significant predictor of disability and mortality. We hypothesised that the 4-m gait speed in COPD patients would correlate well with the 6MW and ISW, and with validated COPD mortality composite scores such as BODE and ADO.
Methods 26 well-characterised COPD patients were studied. Each underwent 6MW test as per ATS guidelines, ISW test and completed a 4-m walk in random order. For the 4-m walk, participants were instructed to walk at their usual speed along a marked, flat unobstructed course. Timing was stopped when the first foot completely crossed the 4-m mark. The faster of two timed walks was used for scoring purposes, and a gait speed was calculated in m/s. Data were analysed using Spearman's rank correlation to assess association between 4-m gait speed and 6MW, ISW, BODE score and ADO index.
Results Baseline characteristics are presented as mean (SD) or median (25th, 75th percentile): 11M: 15 F; age=69 (8); FEV1% predicted=43 (20); 6MW=330 (83); ISW=291 (122.5); MRC dyspnoea 3 (2, 4); St George's Respiratory Questionnaire (SGRQ)=49.6 (21.0); BMI=25.9 (4.9); BODE=4.5 (1.75, 6.0), ADO=5 (4, 6). Mean (SD) 4-m gait speed was 0.96 (0.20) m/s. There was a significant correlation between 4-m gait speed and 6MW (r=0.62, p=<0.001), ISW (r=0.80, p=<0.0001)—see Abstract S73 Figure 1, BODE score (r=−0.56, p=0.003) and ADO index (r=−0.43, p=0.03).
Conclusions 4-m gait speed correlates well with existing functional outcome measures and validated mortality composite scores used in COPD. It is an easy and quick to perform field test, and does not require specialist training or equipment. Further longitudinal and intervention studies are required to validate the 4-m gait speed as an assessment tool.
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