Correlation of six minute walk test with spirometric indices in chronic obstructive pulmonary disease patients: A tertiary care hospital experience

Abstract

Background: Six-minute walk test (6MWT) is a simple, objective, reproducible test which correlated well with different spirometric indices, and thus able to predict severity of chronic obstructive pulmonary disease (COPD) and can replace spirometry in resource poor set-up. Aims and Objectives: To find out correlation between spirometric indices (forced expiratory volume in 1 s (FEV 1 ), forced vital capacity (FVC), and peak expiratory flow rate (PEFR)) and 6-minute walk distance (6MWD) in COPD patients, and thus to assess whether 6MWT can replace spirometry. Settings and Design: Institution based cross-sectional observational study. Materials and Methods: Eighty patients of COPD (diagnosis confirmed by Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2010 criteria) were enrolled for the study after applying exclusion criteria. All patients underwent spirometric measurement of FEV 1 , FVC, PEFR, and ratio of FEV 1 and FVC and test repeated after bronchodilation by 200-400 μg of salbutamol. 6MWT was performed following American Thoracic Society (ATS) protocol of 6MWT and distance was measured in meters. Results: We found significant linear correlation of 6MWT with post-FEV 1 (r = 0.478, P < 0.001), post-FVC (r = 0.454, P < 0.001), and post-PEFR (r = 0.408, P < 0.001), but no correlation with FEV 1 /FVC (r = 0.250, P = 0.025). We also found significant correlation of 6MWT with BODE (body mass index (BMI), airway obstruction, dyspnea, and exercise capacity) index (r = −0.419, P < 0.001). Conclusions: 6MWT can be a useful replacement of spirometry in assessment of severity of COPD.