The TUG-10 test detects exertional desaturation in patients with interstitial lung disease: correlation with 6-minute-walk-test, cardiopulmonary exercise test, and lung diffusion capacity

The Time-Up-and-Go (TUG) test is clinical test, used to assess functional mobility in chronic diseases. A modified version, the TUG-10, involving 10 consecutive repetitions of the classic version, has been recently proposed to increase the physiological demand. However, TUG-10 ability to detect exertional desaturation in patients with interstitial lung disease (ILD) has not been investigated. This study aimed to: (i) compare oxygen desaturation during the TUG-10 with 6-minute walk test (6MWT) and cardiopulmonary exercise test (CPET) in patients with ILD; (ii) examine correlations in exertional desaturation among these tests and with lung diffusing capacity (DLCO). Twenty patients with fibrotic-ILD (70.1 ± 7.3years) performed in random order the TUG-10, 6MWT, and CPET (on a cycle ergometer). Correlations between desaturation indices (SpO₂nadir and SpO₂magnitude, ΔSpO₂) across tests and with DLCO were examined. No significant differences were observed in desaturation among TUG-10, 6MWT, and CPET (ΔSpO2: -7.35 ± 3.8%, 7.0 ± 4.4%, and − 7.1 ± 3.7%, respectively; SpO2nadir: 89.2 ± 4.5%, 88.2 ± 5.2%, and 88.3 ± 4.6%). ΔSpO2 during TUG-10 correlated (p < 0.05) with ΔSpO2 in 6MWT (r = 0.62) and CPET (r = 0.61). SpO₂nadir during TUG-10 correlated (p < 0.001) with SpO₂nadir in 6MWT (r = 0.73) and CPET (r = 0.65). TUG-10 duration (84.4 ± 20.1s) correlated with 6MWT distance (r=-0.83; p < 0.001). SpO₂nadir during TUG-10 correlated with DLCO (r=-0.68; p < 0.001). The TUG-10 is a brief (< 1.5 min) test that can induce exertional desaturation in patients with ILD. TUG-10 desaturation indices strongly correlate with those in 6MWT and CPET, and with DLCO, making it a practical test for detecting exertional desaturation, especially in primary care or private practice with limited equipment and space.