Association between Six-Minute Walk Test and Expiratory Spirometry Parameters in Chronic Obstructive Pulmonary Disease

Background- Many studies have suggested a relationship between the six-minute walk test (6MWT) and pulmonary function test (PFT) parameters in patients with chronic obstructive pulmonary disease (COPD). This study was designed to assess the association between individual PFT parameters and the 6MWT results in our COPD patient population. Methods- Fifty-five patients with COPD (45 men and 5 women), defined as FEV1/FVC < 0.7, were recruited in this study. Spirometry parameters, including forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEFR) and FEV1/FVC ratio, were measured. All the patients underwent the 6MWT within one hour of spirometry. All the COPD subjects were classified as mild, moderate or severe as per ATS criteria.12 Results- There was a statistically significant association between the results of the 6MWT and FEV1, FVC% and PEFR (all p values < 0.001). However, our study did not show any relationship between FEV1 to FVC ratio and the 6MWT results (r = 0.09 and p = 0.52). Using one way analysis of variance, we found a significant relationship between the severity of COPD and the result of the 6MWT (f = 8.78 and p < 0.001). Conclusions- In our COPD patient population, the result of the 6MWT correlated with FEV1, FVC%, as well as PEFR%. This suggests that spirometry data could also be useful in long-term management of COPD patients (Iranian Heart Journal 2005; 6 (3): 59-63).