Validity of 6-min Walk Test in Assessment of Severity among Patients with Chronic Obstructive Pulmonary Disease

Background: The 6-min walk test (6-MWT) is commonly used for evaluation of patients with cardiac or pulmonary diseases and prognostic relevance. Accordingly, the 6-MWT has been used as a primary endpoint in most randomized controlled trials of newly developed therapies in pulmonary arterial hypertension, which is the most common and progressive extrapulmonary manifestation observed among patients with chronic obstructive pulmonary disease (COPD). Materials and Methods: Total 100 male patients who attended the chest medicine out-patient department, with the symptoms suggestive of COPD were included in this study, and the study was done to evaluate the 6-min walking distance (6-MWD) and correlated with echocardiographic findings suggestive of pulmonary hypertension as a predictor of severe COPD in these patients. Result: All the COPD cases enrolled in the study were males, with mean age 59.5 +/- 2.5 years. These patients were grouped under mild (21%), moderate (23%), and severe (56%) groups according to GOLD criteria's. The study results showed that as the COPD severity increases, the incidence of pulmonary hypertension also increases as identified by echocardiographic right ventricular systolic pressure (RVSP) and when correlated with 6-MWD, it substantially decreases as pulmonary pressures increases. The average RVSP was 59.6 +/- 4.4 mmHg in severe COPD patients with mean 6-MWD 134.8 +/- 4.8 m, whereas it was 47.2 +/- 6.8 in moderately severe COPD with 6-MWD of 196.6 +/- 5.7 m while it was 39.3 +/- 5.1 in mild groups with 6-MWD of 316.4 +/- 6.9 m. These values were found to be significant when they were compared to each other in different groups (P < 0.001). Conclusion: 6-MWD may offer a reliable alternative method to assess the severity of COPD as it is well-correlated with the severity of pulmonary hypertension in COPD patients and may help in the follow-up of these patients.