Could the 6-Minute-Walk-Test be a shorter duration and still show significant oxygen desaturation in interstitial lung disease?

<bold>Background:</bold> Oxygen desaturation(S_pO₂%<90%)during the 6-Minute-Walk-Test(6MWT)is an indication for ambulatory oxygen(BTS 2015). Shorter walk duration could benefit patients with more severe interstitial lung disease (ILD) and in remote settings. <bold>Aims:</bold> To compare S_pO_²% recorded during different time points of the 6MWT. To determine the median time to desaturation event (S_pO₂% <90%) for differing ILD severity. <bold>Methods:</bold> Retrospective routine clinical 6MWT and lung function data were analysed. Patients were classed by Distance-Oxygen-Gender-Age-Physiology(DO-GAP)index. <bold>Results:</bold> n=258 patients with ILD. Median (IQR) S_pO₂% recorded at 0-2, 2-4 and 4-6 minutes of 6MWT were 93% (8), 92% (8) and 91% (10) respectively (p<0.001). Prognostically, AUC for predicting 3 -year mortality was significant (p<0.001) and similar for the lowest S_pO₂% recorded between 0-2, 2-4 and 4-6 mins (AUC = 0.76, 0.77, 0.76, respectively). 103 patients experienced S_pO₂% <90% during the 6MWT. Figure 1 compares the median time to desaturation event between the DO-GAP groups (p=0.01). <bold>Conclusion:</bold> For patients who desaturate during a 6MWT, the S_pO₂% mostly falls <90% early in the test. A 3MWT has over 80% sensitivity for identifying ambulatory oxygen desaturation in more severe ILD (DO-GAP groups 2/3). Shorter walk time could detect desaturation which would be efficient, patient-centred, and compatible with remote monitoring. <fig><object-id>erj;64/suppl_68/PA1555/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>