Comparison of six-minute walk test and incremental shuttle walk test in interstitial lung disease

BACKGROUND: This study aimed to compare six-minute walk test (6-MWT) and incremental shuttle walk test (ISWT) in evaluating the exercise capacity and physiological responses of stable patients with interstitial lung disease (ILD). METHODS: Thirty patients diagnosed with ILD who were stable during the study period were included in the study. Demographic characteristics of the patients, lung function tests and carbon monoxide diffusion capacities were recorded. 6-MWT and ISWT were applied to the patients on different days, and physiological responses were evaluated. RESULTS: The mean age of the patients was 52.4 +/- 14 years, and 17 (56.7%) were men. The mean distances covered in the 1st hour and 2nd hour of 6-MWT were 418.2 +/- 137.4 m and 443.4 +/- 143.4 m, respectively, and the difference was statistically significant (P<0.001). ISWT mean distance was 266.3 +/- 148.3 m. The difference between oxygen saturations measured before and after 6-MWT and ISWT ( increment SaO2) was statistically significant (-7,-4) (P<0.001). Both 6-MWT and ISWT showed that there was a significant decrease in the exercise capacity of the patients with ILD, and there was a strong correlation between the walking distances measured in both tests (r=0.719, P<0.001). 6-MWT and ISWT walking distances showed the highest correlation with the maximum carbon monoxide diffusion capacity (DLCO) (%) (r=0.596, P<0.001 vs. r=0.666, P<0.001). CONCLUSIONS: 6-MWT and ISWT can be used to determine the exercise capacity in patients with ILD, and both tests show a strong correlation with DLCO, a parameter that has an important role in diagnosis, follow-up, treatment, and prognosis in this patient group. ISWT is a standardized test in which the maximal capacity is evaluated, it has a strong correlation with maximal and submaximal tests, and the peak oxygen consumption (V02 peak) calculated in this test shows a correlation with DLCO. Hence, ISWT is one step ahead in the follow-up of patients with ILD, monitoring treat-ment response, predicting survival and evaluating candidates for pulmonary rehabilitation program.