Accompanied versus unaccompanied walking for continuous oxygen saturation measurement during 6-min walk test in COPD:...

The aim of this study was to determine if there is a difference in 6-min walk test (6MWT) distance when the assessor accompanies the patient to continuously measure peripheral oxygen saturation (S _pO ) compared to the patient walking unaccompanied.  We conducted a randomised crossover study to evaluate the impact of the assessor walking with the patient during the 6MWT (6MWT_with) versus the patient walking alone (6MWT_without). At the end of a pulmonary rehabilitation programme, each patient performed two 6MWTs in random order and separated by a 30-min rest.  49 patients with chronic obstructive pulmonary disease (COPD) (Global Initiative for Obstructive Lung Disease classification 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- -4.3, p=0.0004). Notably, six patients walked more than 30 m farther (minimal important difference) in one of the two conditions (6MWT_with: n=1, 6MWT_without: n=5). There were no between-sequence-group differences in heart rate, dyspnoea, leg fatigue and S _pO . The median (interquartile range) number and duration of S _pO signal artefacts were high but not different between the experimental conditions (6MWT_with: 17 (4-24), 34 s (7-113 s); 6 MWT_without: 11 (3-26), 24 s (4-62 s)).  At a study population level, we observed a statistically significant difference in 6MWT distance between the two experimental conditions; however, the magnitude of difference was small and may not be 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.