Accompanied versus unaccompanied walking for continuous oxygen saturation measurement during 6-min walk test in COPD: A randomised cross-over study

Is there is a difference in the 6-Minute Walk Test (6MWT) distance when
the assessor accompanies the patient to continuously measure oxygen
saturation (SpO2) compared to the patient walking unaccompanied? We
conducted a randomised cross-over study to evaluate the impact of the
assessor walking with the patient during 6MWT (6MWTwith) versus patient
walking alone (6MWTwithout). At the end of a pulmonary rehabilitation
programme, each patient performed two 6MWTs in random order and separated
by 30 minutes rest. 49 COPD patients (GOLD II-IV) were included. In a
regression model adjusting for period and subject, accompanying the
patient resulted in a lower walking distance (mean difference -9.1 m,
[95%CI, -13.9 to -4.3], p=0.0004). Notably, six patients walked more than
30m further (minimal important difference, MID) in one of the two
conditions (6MWTwith: n=1, 6MWTwithout: n=5). There were no
betweensequence-group differences in heart rate, dyspnoea and leg-fatigue,
and SpO2. The median (interquartile range) number and duration of SpO2
signal artefacts were high but not different between the experimental
conditions (6MWTwith: 17 [4, 24], 34s [7, 113], 6MWTwithout: 11 [3, 26],
24s [4, 62]). On a study population level, we observed a statistically
significant difference in 6MWT distance between the two experimental
conditions, however, the magnitude of difference is small and may not be
considered clinically relevant. Nevertheless, in a clinical setting,
unaccompanied walking resulted in a substantially higher walking distance
in individual patients, pointing towards strictly standardised testing
methodology, in particular in pre-post study designs.