Correlation of six minute walk test and incremental shuttle walk test with severity of airflow obstruction in patients with chronic obstructive pulmonary disease

Context: The field walking tests like 6MWT and ISWT are commonly used indicators of functional capacity in patients with cardiopulmonary diseases. This study was designed to assess the correlation of six minute walk distance (6MWD) and incremental shuttle walk distance (ISWD) with the severity of airflow obstruction (FEV1%) in patients with chronic obstructive pulmonary disease. Aims: Comparison of correlation of six minute walk test and Incremental shuttle walk test with the severity of airflow obstruction in COPD patients.Settings and Design: Hospital-based prospective cross-sectional study in a tertiary care centre. Methods and Material: One hundred and twelve (112) spirometrically confirmed COPD patients underwent 6MWT and ISWT. The diagnosis of COPD and its severity was assessed by the GOLD criteria. 6MWT and ISWT were done on the same patient with a gap of 5–6 hours and the distance walked (6MWD and ISWD) was correlated with the severity of COPD (FEV1). Statistical Analysis Used: One way ANOVA to compare mean distance walked in 6MWT and ISWT with different grades of COPD. Pearson Correlation was done to correlate packyears of smoking and age with 6MWD and ISWD. Results: The mean distance walked in the 6MWT and ISWT was estimated and compared across the four categories of GOLD grading. There was no statistically significant difference between the study subjects of corresponding GOLD grades based on the distance walked in 6MWT and in ISWT. However, a linear correlation was depicted between ISWD and post-bronchodilator FEV1. A model of linear regression showed that ISWD was an independent contributor to post-bronchodilator FEV1 in our study. Conclusions: Incremental shuttle walk test, an externally paced near to standard test with its incremental nature, can be used as an appropriate surrogate for FEV1 in determining the severity of airflow obstruction in COPD patients.